98-5313. Announcement of the Drinking Water Contaminant Candidate List  

  • [Federal Register Volume 63, Number 40 (Monday, March 2, 1998)]
    [Notices]
    [Pages 10274-10287]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 98-5313]
    
    
    
    [[Page 10273]]
    
    _______________________________________________________________________
    
    Part III
    
    
    
    
    
    Environmental Protection Agency
    
    
    
    
    
    _______________________________________________________________________
    
    
    
    Announcement of the Drinking Water Contaminant Candidate List; Notice
    
    Federal Register / Vol. 63, No. 40 / Monday, March 2, 1998 / 
    Notices
    
    [[Page 10274]]
    
    
    
    ENVIRONMENTAL PROTECTION AGENCY
    
    [W-97-11; FRL-5972-5]
    
    
    Announcement of the Drinking Water Contaminant Candidate List
    
    AGENCY: U.S. Environmental Protection Agency (EPA).
    
    ACTION: Notice.
    
    -----------------------------------------------------------------------
    
    SUMMARY: The Safe Drinking Water Act (SDWA), as amended in 1996, 
    requires the Environmental Protection Agency (EPA) to publish a list of 
    contaminants which, at the time of publication, are not subject to any 
    proposed or promulgated national primary drinking water regulation 
    (NPDWR), that are known or anticipated to occur in public water systems 
    and which may require regulations under the SDWA [section 1412(b)(1)]. 
    The SDWA, as amended, specifies that EPA must publish the first list of 
    contaminants (Drinking Water Contaminant Candidate List, or CCL) not 
    later than 18 months after the date of enactment, i.e., by February 
    1998, and every five years thereafter. The SDWA, as amended, also 
    specifies that the CCL must be published after consultation with the 
    scientific community, and after notice and opportunity for public 
    comment.
        A draft CCL was published in the October 6, 1997 edition of the 
    Federal Register (62 FR 52193) in order to seek comment from the 
    public. Seventy-one comments were received. The comments have been 
    reviewed and considered in creating the final CCL presented in today's 
    notice. The CCL is divided among contaminants which are identified as 
    priorities for drinking water research, those which need additional 
    occurrence data, and contaminants which are priorities for 
    consideration for the development of future drinking water regulations 
    and guidance. The CCL includes 50 chemical and 10 microbiological 
    contaminants/contaminant groups.
        The full record for this notice has been established under docket 
    number W-97-11, and includes supporting documentation as well as all 
    comments received in response to the October 6, 1997 notice. The full 
    record is available for inspection from 9:00 a.m. to 4:00 p.m., Monday 
    through Friday, excluding legal holidays at the Office of Water Docket, 
    East Tower Basement, USEPA Headquarters, 401 M Street, S.W., 
    Washington, D.C. For access to the docket, please call 202-260-3027 to 
    schedule an appointment.
    
    FOR FURTHER INFORMATION CONTACT: For general information, please 
    contact the EPA Safe Drinking Water Hotline. The toll-free number is 
    800-426-4791. The Hotline operates from 9:00 a.m. to 5:30 p.m., Monday 
    through Friday, excluding legal holidays. For specific information on 
    the Contaminant Candidate List and the contaminant identification 
    process, please contact Ms. Evelyn Washington, at the U.S. 
    Environmental Protection Agency, Office of Ground Water and Drinking 
    Water, Mailcode 4607, Washington, D.C. 20460, phone: 202-260-3029, fax: 
    202-260-3762, email: washington.evelyn@epamail.epa.gov.
    
    EPA Regional Offices
    
    I. JFK Federal Bldg., Room 2203, Boston, MA 02203. Phone: 617-565-3602, 
    Jerry Healey
    II. 290 Broadway, Room 2432, New York, NY 10007-1866. Phone: 212-637-
    3880, Walter Andrews
    III. 841 Chestnut Street, Philadelphia, PA 19107. Phone: 215-566-5775, 
    Jeff Hass
    IV. 61 Forsyth Street, SW, Atlanta GA 30303. Phone: 404-562-9480, 
    Janine Morris
    V. 77 West Jackson Blvd., Chicago, IL 60604-3507. Phone: 312-886-4239, 
    Kim Harris
    VI. 1445 Ross Avenue, Dallas, TX 75202. Phone: 214-665-7150, Larry 
    Wright
    VII. 726 Minnesota Ave., Kansas City, KS 66101. Phone: 913-551-7410, 
    Stan Calow
    VIII. One Denver Place, 999 18th Street, suite 500, Denver, CO 80202. 
    Phone: 303-312-6627, Rod Glebe
    IX. 75 Hawthorne Street, San Francisco, CA 94105. Phone: 415-744-1884, 
    Bruce Macler
    X. 1200 Sixth Avenue, Seattle, WA 98101. Phone: 206-553-1893, Larry 
    Worley
    
    SUPPLEMENTARY INFORMATION:
    
    Abbreviations Used in This Notice
    
    AMA--American Medical Association
    AWWARF--American Water Works Association Research Foundation
    CAA--Clean Air Act
    CASRN--Chemical Abstract Services Registry Number
    CCL--Contaminant Candidate List
    CERCLA--Comprehensive Environmental Response, Comprehensive and 
    Liability Act
    CPVC--Chlorinated Polyvinyl Chloride
    DBPR--Microbiological and Disinfection Byproducts Regulations
    DWEL--Drinking Water Equivalent Level
    DWPL--Drinking Water Priority List
    EDSTAC--Endocrine Disruptor Screening and Testing Advisory Committee
    EPA--Environmental Protection Agency
    ESWTR--Enhanced Surface Water Treatment Rule
    FIFRA--Federal Insecticide, Fungicide, and Rodenticide Act
    FQPA--Food Quality Protection Act
    FR--Federal Register
    GWDR--Ground Water
    GW--Ground Water Disinfection Rule
    IRIS--Integrated Risk Information System
    MCL--Maximum Contaminant Level
    MCLG--Maximum Contaminant Level Goal
    MTBE--Methyl-t-butyl Ether
    NAS--National Academy of Sciences
    NAWQA--National Water Quality Assessment Program
    NDWAC--National Drinking Water Advisory Council
    NOAEL--No-Observed-Adverse-Effect-Level
    NPDWR--National Primary Drinking Water Regulations
    NPL--National Priority List
    NSF--National Sanitation Foundation
    OPP--EPA's Office of Pesticide Programs
    OPPTS--EPA's Office of Pollution Prevention and Toxic Substances
    PGWDW--Pesticides in Ground Water Database
    PVC--Polyvinyl Chloride
    RfD--Reference Dose
    SAB--EPA's Science Advisory Board
    SAP--Science Advisory Panel
    SDWA--Safe Drinking Water Act
    SWTR--Surface Water Treatment Rule
    TTHM--total trihalomethane
    TSCA--Toxic Substances Control Act
    UCMR--Unregulated Contaminant Monitoring Regulations
    WHO--World Health Organization
    
    Table of Contents
    
    I. Background
    II. Drinking Water Contaminant Candidate List
        Table 1. Drinking Water Contaminant Candidate List
    III. Changes Made to Create the Final Contaminant Candidate List 
    Based on Comments Received on the Draft
        A. Acetochlor, Metolachor, and Alachlor ESA
        B. Acetone and Cumene
        C. Aldicarbs and Nickel
        D. Aluminum
        E. Dimethoate
        F. DTBB
        G. Methyl Bromide
        H. Microorganisms
        I. MTBE
        J. Organotins
        K. Perchlorate
        L. Rhodamine WT
        M. Sodium
        N. Triazines
        O. Zinc
    IV. Continuing Work in Preparation for Future CCLs
        A. Pesticides Deferred
        B. Endocrine Disruptors
    
    [[Page 10275]]
    
        C. Development of the Contaminant Selection Process
    V. Data, Research Needs and Next Steps
        Table 2. Next Steps for the CCL
    VI. Other Requirements
    VII. References
    
    I. Background
    
        The Safe Drinking Water Act (SDWA), as amended in 1996, requires 
    the Environmental Protection Agency (EPA) to publish a list of 
    contaminants that are known or anticipated to occur in public water 
    systems, and which may require regulation under the SDWA [section 
    1412(b)(1)]. The SDWA, as amended, also specifies that EPA must publish 
    this list of contaminants (Drinking Water Contaminant Candidate List, 
    or CCL) not later than 18 months after the date of enactment (i.e., by 
    February 1998), and publish a new CCL every five years thereafter. The 
    SDWA requires that the list of contaminants include those which, at the 
    time of publication, are not subject to any proposed or promulgated 
    national primary drinking water regulation (NPDWR). The list must be 
    published after consultation with the scientific community, including 
    the Science Advisory Board, after notice and opportunity for public 
    comment, and after consideration of the occurrence database established 
    under section 1445(g). The unregulated contaminants considered for the 
    list must include, but not be limited to, substances referred to in 
    section 101(14) of the Comprehensive Environmental Response, 
    Compensation, and Liability Act of 1980 (CERCLA), and substances 
    registered under the Federal Insecticide, Fungicide, and Rodenticide 
    Act (FIFRA).
        Today's notice is being published pursuant to the requirements in 
    section 1412(b)(1). The contaminants included are not subject to any 
    proposed or promulgated national primary drinking water regulation, are 
    known or anticipated to occur in public water systems, and may require 
    regulation under the SDWA. During the development of the CCL, the 
    Agency consulted with stakeholders, including the National Drinking 
    Water Advisory Council's (NDWAC) Working Group on Occurrence & 
    Contaminant Selection, which includes microbiologists, toxicologists, 
    public health scientists, and engineers, and consulted with other 
    members of the scientific community including the Science Advisory 
    Board (SAB). A draft CCL was published in the October 6, 1997 edition 
    of the Federal Register (62 FR 52193) to seek comment from the public.
        Seventy-one comments were received in response to the notice on the 
    draft CCL; 66 comments were received by the due date, and an additional 
    5 comments were received later. The majority were supportive of the CCL 
    process and the development of this first CCL, and provided suggestions 
    on specific contaminants that should be included on, or excluded from, 
    the CCL. The comments, data, and information provided were taken into 
    consideration in preparing the final CCL presented in today's notice. 
    Modifications to the CCL presented in today's notice were also reviewed 
    by the National Drinking Water Advisory Council (NDWAC), and the NDWAC 
    Working Group on Occurrence & Contaminant Selection.
        The Agency believes the CCL presented in today's notice is a first 
    step toward improving risk assessment, strengthening science and data, 
    and achieving better decision-making and future priority setting. The 
    CCL is designed to be responsive to each of the requirements noted 
    above of the SDWA, as amended, and is consistent with the goals of the 
    Drinking Water Redirection Strategy. The CCL is the result of a 
    concerted effort of screening a larger set of contaminants to a subset 
    of those of most concern.
        This final CCL will be the primary source of priority contaminants 
    for the Agency's drinking water program. The list is divided among 
    priorities for drinking water research, priorities for additional 
    occurrence data collection, and those contaminants which are priorities 
    for consideration for Agency determinations of whether or not to 
    regulate specific contaminants by August 2001.
        The SDWA does not preclude the Agency from taking action on a 
    contaminant not included on the CCL. The EPA can decide to monitor, 
    develop guidance, or conduct research, for a contaminant not included 
    on the CCL. The Agency can also develop regulations to address an 
    urgent threat to public health under SDWA [section 1412(b)(1)(D)]. The 
    Agency is also not precluded from modifying the CCL prior to the due 
    date of the next CCL, which is February 2003.
    
    II. Drinking Water Contaminant Candidate List
    
        The following table includes the contaminants, microbiological and 
    chemical, presented as the Drinking Water Contaminant Candidate List. 
    The chemical contaminants in the table are identified by name and 
    Chemical Abstracts Service Registry Number (CASRN). The CCL includes 50 
    chemical and 10 microbiological contaminants/contaminant groups.
    
               Table 1.--Drinking Water Contaminant Candidate List          
    ------------------------------------------------------------------------
                          Microbiological contaminants                      
    -------------------------------------------------------------------------
    Acanthamoeba (guidance expected for contact lens wearers)               
    Adenoviruses                                                            
    Aeromonas hydrophila                                                    
    Caliciviruses                                                           
    Coxsackieviruses                                                        
    Cyanobacteria (blue-green algae), other freshwater algae, and their     
     toxins                                                                 
    Echoviruses                                                             
    Helicobacter pylori                                                     
    Microsporidia (Enterocytozoon & Septata)                                
    Mycobacterium avium intracellulare (MAC)                                
    ------------------------------------------------------------------------
    
    
                                                                            
                      Chemical contaminants                        CASRN    
    1,1,2,2-tetrachloroethane...............................         79-34-5
    1,2,4-trimethylbenzene..................................         95-63-6
    1,1-dichloroethane......................................         75-34-3
    1,1-dichloropropene.....................................        563-58-6
    1,2-diphenylhydrazine...................................        122-66-7
    1,3-dichloropropane.....................................        142-28-9
    1,3-Dichloropropene.....................................        542-75-6
    
    [[Page 10276]]
    
                                                                            
    2,4,6-trichlorophenol...................................         88-06-2
    2,2-dichloropropane.....................................        594-20-7
    2,4-dichlorophenol......................................        120-83-2
    2,4-dinitrophenol.......................................         51-28-5
    2,4-dinitrotoluene......................................        121-14-2
    2,6-dinitrotoluene......................................        606-20-2
    2-methyl-Phenol (o-cresol)..............................         95-48-7
    Acetochlor..............................................      34256-82-1
    Alachlor ESA & other acetanilide pesticide degradation                  
     products...............................................             N/A
    Aldrin..................................................        309-00-2
    Aluminum................................................       7429-90-5
    Boron...................................................       7440-42-8
    Bromobenzene............................................        108-86-1
    DCPA mono-acid degradate................................        887-54-7
    DCPA di-acid degradate..................................       2136-79-0
    DDE.....................................................         72-55-9
    Diazinon................................................        333-41-5
    Dieldrin................................................         60-57-1
    Disulfoton..............................................        298-04-4
    Diuron..................................................        330-54-1
    EPTC (s-ethyl-dipropylthiocarbamate)....................        759-94-4
    Fonofos.................................................        944-22-9
    Hexachlorobutadiene.....................................         87-68-3
    p-Isopropyltoluene (p-cymene)...........................         99-87-6
    Linuron.................................................        330-55-2
    Manganese...............................................       7439-96-5
    Methyl bromide..........................................         74-83-9
    Methyl-t-butyl ether (MTBE).............................       1634-04-4
    Metolachlor.............................................      51218-45-2
    Metribuzin..............................................      21087-64-9
    Molinate................................................       2212-67-1
    Naphthalene.............................................         91-20-3
    Nitrobenzene............................................         98-95-3
    Organotins..............................................             N/A
    Perchlorate.............................................             N/A
    Prometon................................................       1610-18-0
    RDX.....................................................        121-82-4
    Sodium..................................................       7440-23-5
    Sulfate.................................................      14808-79-8
    Terbacil................................................       5902-51-2
    Terbufos................................................      13071-79-9
    Triazines & degradation products of triazines                           
     (including, but not limited to Cyanazine 21725-46-2,                   
     and atrazine-desethyl 6190-65-4).......................                
    Vanadium................................................       7440-62-2
    ------------------------------------------------------------------------
    
    III. Changes Made to Create the Final Contaminant Candidate List Based 
    on Comments Received on the Draft
    
        The criteria which EPA used to select the contaminants for the CCL 
    are described in detail in the October 6, 1997 notice (62 FR 52193) on 
    the draft CCL. In general, the criteria for including a contaminant on 
    the CCL consisted of determinations of whether the occurrence, or 
    anticipated occurrence, of a contaminant was likely at levels of 
    concern to human health. The October notice solicited input from the 
    public and specifically requested comments on (1) the approach EPA used 
    to create the list and suggestions on the process for future lists; (2) 
    contaminants on the list; (3) data needs categories; and (4) whether to 
    include perchlorate on the CCL.
        EPA received 71 comments, 66 by the deadline and 5 additional late 
    comments. The majority of comments were supportive of the CCL process, 
    and the development of this first CCL. Comments were received from a 
    number of segments of the stakeholder community, including equipment 
    manufacturers, consultants, chemical manufacturers, trade associations, 
    environmental groups, state regulatory agencies, water utilities, and 
    private citizens. Commenters provided data and information on specific 
    contaminants and included suggestions on the process for future CCL 
    development, as well as feedback on the data and research needs 
    indicated for the contaminants on the CCL. Roughly 60 issues were 
    raised by the comments, both contaminant-specific and related to the 
    development of a process for identifying contaminants for future CCLs. 
    The comments, data, and information provided were taken into 
    consideration in preparing the final CCL presented in today's notice. 
    Proposed changes to the CCL were also reviewed by the NDWAC Working 
    Group on Occurrence & Contaminant Selection, and the NDWAC full-
    Council.
        A number of comments indicated that many did not understand the 
    function of the CCL. The CCL is not the list of contaminants for which 
    the Agency has made a determination to regulate. The CCL is a list of 
    priority contaminants (not otherwise addressed) for drinking water 
    program activities which include those for: (1) drinking water 
    research, (2) monitoring, (3) guidance development, as well as those 
    for (4) selection and regulatory determination by the year 2001. The 
    next steps likely to occur with regard to any given contaminant are 
    discussed in more detail in Section V in today's notice.
        Despite the support expressed for the development of this first 
    CCL, commenters advised that more robust criteria are needed for future 
    CCL
    
    [[Page 10277]]
    
    development and for contaminant selection. The Agency agrees with these 
    commenters and will continue to work to develop a contaminant 
    identification process for chemical and microbiological contaminants to 
    be used to develop future CCLs. Section IV.C. of today's notice 
    provides additional information on how the Agency plans to develop 
    these processes.
        The following is a summary of the significant public comments 
    received that led to changes to the CCL. The remainder of this section 
    responds to the more significant comments, and indicates how the CCL 
    was changed in response to these comments. A complete report of 
    responses to all comments received on the notice of the draft CCL can 
    be found in the docket.
    
    A. Acetochlor, Metolachor, and Alachlor ESA
    
        A number of commenters supported the inclusion of acetochlor, 
    metolachor, and alachlor ESA (the sulfonic acid degradate of alachlor) 
    on the CCL, while others indicated that they should not be included. 
    Three commenters indicated that acetochlor should have low priority for 
    regulation, and that the Agency should consider deleting it from the 
    CCL. The commenters argued that under the Acetochlor Registration 
    Project, the EPA has established very conservative triggers for its 
    potential cancellation of use as a pesticide. The commenters went on to 
    indicate that in 175 community water systems monitored since March 
    1995, acetochlor detections have occurred in only 20% of samples, that 
    no system had an average mean concentration exceeding 2 ppb, which is 
    one of the triggers, and that additional monitoring data will indicate 
    that concentrations found in public water systems are far below 140 
    ppb.
        One commenter argued that metolachlor should not be included on the 
    CCL. That although it is detected in water, it is rarely above the 
    lifetime health advisory level of 70 ppb, and the detections in most 
    cases are associated with point sources. The commenter stated that data 
    collected under the Unregulated Contaminant Monitoring Regulations is 
    available on a state-by-state basis, and the results reported from 3 
    States also indicate no detections above the lifetime health advisory 
    level of 70 ppb. Another commenter suggested that alachlor ESA should 
    not be included on the CCL, as it, too, should have a low priority for 
    regulation based on concentrations in water not exceeding 6370 ppb.
        Other commenters argued that metolachor, acetochlor, and alachlor 
    ESA should be kept on the CCL since States reported finding these 
    contaminants in water. One commenter added that the metolachor ESA and 
    metolachor OA degradation products should be included on the CCL also, 
    since all have been found in ground water.
        One commenter also pointed out that metolachlor, acetochlor, and 
    alachlor do not have a common mode of action, and thus cannot be 
    grouped together to develop a single standard to address all 
    acetanilide pesticides.
    EPA Response
        The Agency disagrees with the commenters who believe it is 
    inappropriate to include acetochlor, metolachor, and alachlor ESA on 
    the CCL. By including these contaminants on the CCL, the Agency has not 
    yet made a determination with respect to regulating any of them. In 
    light of the reported occurrences of these contaminants in water, the 
    drinking water program needs to determine what action is appropriate to 
    ensure the protection of public health even if the action may be only 
    the development of guidance for States and public water systems. The 
    Office of Water will evaluate further the available toxicity and 
    occurrence information for these pesticides in order to determine 
    appropriate concentration values adequate to protect against risks 
    associated with exposure through drinking water. With respect to 
    metolachlor specifically, the Agency believes it is appropriate to 
    include it on the CCL. The data collected under the Unregulated 
    Contaminant Monitoring Regulations is being collected from all States 
    and will be compiled and evaluated as additional information is 
    collected and evaluated for all contaminants on the CCL.
        The Agency agrees that it is appropriate to include other 
    acetanilide pesticide degradation products in addition to alachlor ESA, 
    since they, too, have been found in ground water. However, at this 
    time, the Agency has not yet determined which are the most important to 
    include; therefore, EPA has decided to include alachlor ESA & other 
    acetanilide pesticide degradation products as a group of contaminants 
    on the CCL. The determination of which degradation products are of most 
    concern will be determined as we learn more about these contaminants as 
    a class. The Agency also agrees with the commenter that because 
    alachlor, acetochlor, and metolachlor do not have a common mode of 
    action, they are not at this time appropriate contaminants to be 
    grouped together to develop a single approach addressing all 
    acetanilide pesticides. Contrary to earlier statements, acetanilide 
    pesticides are not likely candidates for development of ``total 
    standards'' in the foreseeable future. However, the Agency is 
    interested in the development of ``total standards,'' or standards that 
    address classes of compounds, where appropriate, and as the state of 
    the science improves.
    
    B. Acetone and Cumene
    
        Two commenters remarked that outdated oral reference doses (RfD) 
    from the Integrated Risk Information System (IRIS) for acetone and 
    cumene were used in developing the draft CCL and that analyses should 
    be done with current information. The Chemical Manufacturers 
    Association's Acetone Panel submitted comments about acetone and 
    recommended that it should not be included on the final CCL. The reason 
    given, in addition to the outdated RfD, was that outdated information 
    concerning levels of acetone detected in the environment, including 
    data from old National Priority List (NPL) sites had been used in the 
    Agency's evaluation and that this did not provide a reliable basis for 
    estimating likely levels of acetone in drinking water or sources of 
    drinking water. The Panel believes more relevant information shows that 
    acetone is unlikely to be present in drinking water or sources of 
    drinking water at levels of concern.
        The Chemical Manufacturers Association's Cumene Panel submitted 
    comments about cumene and recommended that it should not be included on 
    the final CCL. The reason given, in addition to the outdated RfD, was 
    that concentrations of cumene detected in the environment were not at 
    levels of concern, and it is rarely detected in drinking water or 
    sources of drinking water.
    EPA Response
        The Agency agrees with the commenters that the current IRIS values 
    should be used in the evaluations for developing the CCL. The updated 
    value for acetone has not been posted on the IRIS database; however, 
    the Agency has acknowledged the new value of 0.9 mg/kg/day previously 
    in a notice concerning section 313 of the Emergency Planning and 
    Community Right-to-Know Act (60 FR 31644). The updated value for cumene 
    has been posted on the IRIS database, and is 0.1 mg/kg/day.
        The occurrence data from the U.S. Geological Survey's National 
    Water Quality Assessment Program (NAWQA) indicates that acetone was 
    detected at a
    
    [[Page 10278]]
    
    frequency of greater than 10% of the samples collected; however, the 
    concentrations found did not exceed their reporting level of 0.2 
    g/l. When the current IRIS values are used for acetone and 
    cumene, and compared to the available occurrence data, neither meets 
    the criteria set forth for identifying contaminants for the CCL, and 
    therefore, acetone and cumene have been removed from the CCL.
    
    C. Aldicarbs and Nickel
    
        EPA received a number of comments encouraging the inclusion of 
    aldicarbs and nickel on the CCL, while a few commented that it was 
    inappropriate to include these contaminants, despite the Agency's 
    existing statutory obligation with regard to these contaminants.
    EPA Response
        In the case of aldicarbs (aldicarb, aldicarb sulfoxide, aldicarb 
    sulfone) and nickel, the Agency has determined that it is inappropriate 
    to include these contaminants on the CCL. The 1996 Amendments to SDWA 
    explicitly reenacted the requirements for regulation of these 
    contaminants [section 1412 (b)(2)]. In response to an administrative 
    petition from the manufacturer Rhone-Poulenc, the Agency issued an 
    administrative stay of the effective date of the maximum contaminant 
    levels (MCLs) for aldicarbs, and they never became effective. NPDWRs 
    for nickel were promulgated on July 17, 1992, but the MCL was later 
    vacated and remanded in response to a lawsuit from the Nickel 
    Development Institute and other industry parties.
        The Agency intends to complete regulatory action for both aldicarbs 
    and nickel. The time-frame of completing action for these contaminants 
    is likely to be the same time-frame required by SDWA for regulatory 
    determinations for contaminants on the CCL. When considering the nature 
    and type of work necessary to complete action on these contaminants, 
    the effort for aldicarbs is anticipated to be less extensive than that 
    required for nickel; thus, regulations for aldicarbs are likely to be 
    completed prior to regulations for nickel.
    
    D. Aluminum
    
        EPA received four comments recommending that aluminum not be 
    included on the CCL. One commenter stated that regulations would be 
    premature at this time, due to the need for additional information on 
    the risk of adverse effects and occurrence in drinking water. Other 
    commenters argued that there was no scientific health basis for the 
    inclusion of aluminum on the CCL, and that the World Health 
    Organization (WHO) stated in 1995 that there is an inadequate basis for 
    revising existing guidelines for aluminum below the 200 g/l 
    standard used to control taste and odor effects. The commenters also 
    explained that the source of aluminum in drinking water is primarily 
    linked to the use of alum as a flocculent in water treatment, and the 
    implications of regulating aluminum at lower levels could cause 
    deleterious effects on water quality.
        An additional commenter felt that aluminum should be included on 
    the CCL based on new literature on the relationship of aluminum to 
    Alzheimer's Disease, elderly mental impairment, and childhood learning 
    disabilities. The commenter disagreed with the need for additional data 
    on the health impacts of aluminum. The commenter contends that much 
    more is actually known today about how aluminum causes neurological 
    injury than is known for lead, and that there is as much data on the 
    health effects of aluminum as was ever available for lead.
    EPA Response
        The Agency disagrees with the commenters who indicated that 
    aluminum should not be on the CCL. The Agency believes it is 
    appropriate to include aluminum on the CCL because of the new 
    developments and research on aluminum epidemiology indicating a 
    potential link between aluminum and adverse neurological effects. It is 
    clear that additional studies are needed to characterize the risk of 
    this contaminant from exposure through drinking water.
        Due to aluminum's widespread occurrence and the recent studies 
    indicating some association with Alzheimer's like symptoms and other 
    potential neurotoxic effects, the Agency believes aluminum warrants 
    further investigation. It is also EPA's opinion that additional data 
    are needed to determine an adequate no-observed-adverse-effect-level 
    (NOAEL) for potential chronic neurotoxicity. The inclusion of a 
    contaminant on the CCL does not necessarily mean that the contaminant 
    will be regulated. Contaminants on the CCL include those priorities for 
    which the Agency must make a determination of whether or not to 
    regulate by the year 2001, and priority contaminants for which the 
    Agency will gather additional data and conduct research. At this time, 
    the EPA has included aluminum among the contaminants for which 
    additional research is needed.
    
    E. Dimethoate
    
        One commenter suggested that dimethoate be deleted from the CCL. 
    The major reasons given were that dimethoate did not meet the 
    occurrence criteria, because data used in the Agency's analysis from 
    the Pesticides in Ground Water Database (PGWDB) report were recorded 
    erroneously, and that the IRIS values lack critical evaluation and 
    therefore should not be considered in evaluating whether a contaminant 
    should be included on the CCL.
    EPA Response
        The Agency agrees with the commenter on the point raised about the 
    occurrence data, but not on the point raised about the use of IRIS 
    values. Based on the faulty occurrence data, dimethoate has therefore 
    been removed from the CCL.
        In general, the RfD is an estimate (with uncertainty spanning 
    perhaps an order of magnitude) of a daily exposure to the human 
    population (including sensitive subgroups) that is likely to be without 
    an appreciable risk of deleterious effects during a lifetime. The 
    health assessment information and RfD values on a chemical substance 
    are included in IRIS only after a comprehensive review of chronic 
    toxicity data by U.S. EPA health scientists from several program 
    offices and the Office of Research and Development. The Agency believes 
    it is entirely appropriate to use RfD values reported to IRIS in the 
    absence of drinking water health advisory values in the derivation of 
    health levels of concern for determining if a contaminant should be 
    included on the CCL.
        However, according to EPA's Office of Pesticide Programs (OPP), the 
    office that prepared the PGWDB report, and the Georgia Department of 
    Natural Resources, the data reported for the State of Georgia are 
    incorrect. The laboratory analysis sheets from the Georgia Ground Water 
    Management Laboratory Program indicate dimethoate was not detected in 
    any samples in the State. By eliminating the occurrence data from the 
    PGWDB report for the State of Georgia and replacing it with this new 
    information, which the Agency feels is appropriate, dimethoate no 
    longer meets the criteria for inclusion on the CCL, and has therefore 
    been removed.
    
    F. DTBB
    
        DTBB, also known as 2,6-di-tert-butyl-p-benzoquinone, is a 
    contaminant that appears to be associated with sewage contamination of 
    ground water, and is
    
    [[Page 10279]]
    
    considered by some to be a good indicator of such contamination. DTBB 
    was determined not to meet the criteria for the CCL per se, but was 
    included on the draft list nevertheless, because of the persistent 
    nature of the contaminant, and its potential to serve as an indicator. 
    One commenter stated that coliforms and nitrate already serve the 
    purpose as indicators of contamination, and that it was pointless to 
    include DTBB on the CCL, since it, in fact, did not meet the criteria.
    EPA Response
        The Agency agrees with the commenter and has removed DTBB from the 
    CCL. DTBB does not meet criteria set forth for identifying contaminants 
    for the CCL, and since there are currently acceptable indicators of 
    sewage contamination in the use of total coliforms, its inclusion is 
    unnecessary.
    
    G. Methyl Bromide
    
        Several commenters supported the inclusion of methyl bromide on the 
    CCL. The principal reason cited by commenters was the widespread use of 
    methyl bromide as a fumigant and its likely occurrence in drinking 
    water sources. One commenter indicated that although the frequency of 
    detection in samples was less than 0.1% in ambient water monitoring 
    conducted by the U.S. Geological Survey, methyl bromide should be 
    considered for inclusion because the environmental significance may 
    warrant it.
    EPA Response
        Methyl bromide, which is also known as bromomethane, was included 
    on the draft CCL based on input from stakeholders that it was found in 
    drinking water. In response to the comments, EPA has reevaluated the 
    available information on methyl bromide occurrence. Contrary to 
    assertions of likely widespread occurrence in source water due to its 
    use as a fumigant, the U.S. Geological Survey ambient water monitoring 
    indicates it occurs at less than 0.1% frequency, at very low 
    concentrations (less than 0.2 g/l). However, unregulated 
    contaminant monitoring data collected from States indicates methyl 
    bromide occurred in 0.8% of the public water systems. One explanation 
    for this apparent anomaly could be that the finished water occurrence 
    comes not from its use as a fumigant, but that methyl bromide is 
    associated with the disinfection processes used for drinking water 
    treatment. Nevertheless, methyl bromide met the criteria for inclusion 
    on the CCL; the concentrations reported (maximum 29 g/l) in 
    the unregulated contaminants database exceeded the health level of 0.8 
    g/l.
        Methyl bromide is a gas produced by both manmade and natural 
    sources. Methyl bromide is primarily used for soil fumigation (87%), 
    but its other agricultural uses include: commodity and quarantine 
    treatment (8%), and structural fumigation (5%). When used as a soil 
    fumigant, methyl bromide is injected into the soil at a depth of 12 to 
    24 inches. About 50 to 95% of the methyl bromide injected in the soil 
    eventually enters the atmosphere. About 80 to 95% of the amount used 
    for commodity treatments, and well over 90% used for structural 
    fumigation eventually enters the atmosphere. A significant quantity of 
    methyl bromide used for agricultural purposes is known to escape to the 
    atmosphere due to its volatile nature. Therefore, the U.S. Geological 
    Survey data indicating less than 0.1% frequency of occurrence is 
    consistent with what would be expected to present in ground water due 
    to methyl bromide's use as a fumigant.
        Methyl bromide is also considered a Class I ozone depleting 
    substance, and as such, its use is being phased out around the world by 
    the Montreal Protocol, and in the U.S., by the Clean Air Act (CAA). The 
    Montreal Protocol is an international treaty developed to protect the 
    earth from the detrimental effects of ozone depletion, and to control 
    the production and trade of ozone depleting substances on a global 
    basis. Title VI of the CAA, as amended in 1990, requires that certain 
    ozone depleting substances be phased out in the U.S. within seven 
    years. Under the CAA, the EPA has prohibited the production and 
    importation of methyl bromide starting January 1, 2001. As a result, 
    given methyl bromide's lack of persistence, occurrence in source waters 
    will likely decrease even more.
        If methyl bromide is a disinfection byproduct, EPA has a number of 
    rules and activities currently in place and under development to 
    address it. In 1979, EPA issued an NPDWR establishing an MCL for the 
    total trihalomethanes (TTHMs) disinfection byproducts. The Agency is 
    also in the process of updating the disinfection byproducts regulation. 
    In 1994, EPA proposed a revised standard for TTHMs and a new standard 
    for haloacetic acids. The TTHMs were regulated not only to control 
    trihalomethanes, but also to protect against other similar byproducts. 
    Because of structural similarity, steps to reduce formation of TTHMs 
    would also reduce formation of methyl bromide. The treatment technique 
    of enhanced coagulation, included in the 1994 proposed DBPR, will 
    remove disinfection byproduct precursors, thus reducing the levels of 
    disinfection byproducts in finished waters. Although methyl bromide is 
    not a TTHM, for which an MCL is explicitly established, the Agency 
    believes it would be effectively controlled under the DBPR. However, it 
    is not clear whether methyl bromide is being formed due to 
    disinfection.
        Because it cannot be determined whether methyl bromide is being 
    formed due to disinfection, and its use as a fumigant cannot be 
    completely dismissed as source of drinking water contamination, the 
    Agency has decided to retain methyl bromide on the CCL. At the January 
    7, 1998 meeting, the NDWAC Working Group on Occurrence & Contaminant 
    Selection concurred with the EPA recommendation to delete methyl 
    bromide because it was being addressed in ongoing rulemakings for 
    disinfection byproducts. However, at the February 2, 1998 meeting, the 
    full NDWAC recommended the Agency retain methyl bromide on the CCL 
    after receiving comment that because it is a mono-halogenated compound, 
    it was not specifically regulated with the TTHM family which are tri-
    halogenated compounds, and that it may not turn out to be a 
    disinfection byproduct. At the meeting, EPA was insufficiently lucid in 
    explaining the connection between the TTHM byproducts and the control 
    of similar byproducts. Nonetheless, after further consideration of the 
    NDWAC recommendation, and given the uncertainties about the source, EPA 
    has concluded that methyl bromide should remain on the CCL.
        Since methyl bromide is a gas, most health studies have used the 
    inhalation route of exposure, and the effects of oral exposure have 
    received limited attention. In 1989, EPA classified methyl bromide as a 
    Group D carcinogen (not classifiable) due to inadequate bioassay data. 
    At the time of the IRIS assessment, also in 1989, a chronic oral study 
    was not available, therefore an additional uncertainty factor of 10 
    (total uncertainty of 1,000) was applied to the RfD calculation. 
    However, since the IRIS assessment, a 2-year rat feeding study showed 
    no evidence of carcinogenicity, and a National Toxicology Program 
    inhalation study, conducted in 1992, found no evidence of 
    carcinogenicity. The Agency will also explore the potential sources of 
    drinking water contamination, and the expected impact of the prohibited 
    production and importation of methyl bromide which begins in January 1, 
    2001. Methyl bromide is listed on the Research Priorities portion of 
    the CCL to
    
    [[Page 10280]]
    
    allow the Agency time to better determine the drinking water risk due 
    to this contaminant.
    
    H. Microorganisms
    
        Many commenters stated that the rationale for the inclusion of 
    microorganisms appeared to be inconsistent. They suggested that other 
    microorganisms would have been included had the criteria been used 
    consistently. It was not the intention of EPA, nor the participants of 
    the EPA Drinking Water Microbiology and Public Health Workshop, to 
    develop a comprehensive list of all possible agents of waterborne 
    disease. The intent was to list what were considered the most important 
    agents (or potential agents) of waterborne disease. The Agency 
    recognizes that the Workshop participants could have established 
    different lists of reasonable criteria for selecting pathogens, and 
    believes that the ultimate decisions represent the best (albeit 
    sometimes subjective) judgment of the panel. Nevertheless, the Agency 
    believes that the process for developing the current CCL for 
    microorganisms by this group of nationally recognized experts in the 
    field of microbiology was reasonable and credible.
        EPA believes that regulations that are currently in effect [Surface 
    Water Treatment Rule (SWTR), Total Coliform Rule (TCR)] or are now 
    under development [e.g., Groundwater Disinfection Rule (GWDR), Enhanced 
    Surface Water Treatment Rule (ESWTR), and Disinfection Byproducts 
    Regulations (DPBR)] will address a number of the microorganisms that 
    commenters have suggested. Generally, if a microorganism has not 
    caused, or not expected to cause, a waterborne outbreak in the U.S., or 
    if the organism is known to be susceptible to disinfection or 
    filtration required by current or upcoming regulations, the organism 
    has not been included on the CCL.
    Protozoa
        Several commenters supported the draft CCL, which included 
    Toxoplasma gondii, Cyclospora cayetanensis, and two microsporidia--
    Enterocytozoon and Septata. One commenter suggested the addition of 
    Entamoeba histolytica to the CCL, primarily because of its virulence. 
    One commenter suggested that EPA add Isospora belli to the final CCL.
    EPA Response
        After further consideration, EPA has decided to remove Toxoplasma 
    and Cyclospora from the final CCL. Toxoplasma gondii is about the same 
    size as Giardia, and Cyclospora cayetanensis is larger than 
    Cryptosporidium. The Agency believes that the upcoming M/DBPR to 
    control Giardia and Cryptosporidium will also control these larger 
    organisms. Microsporidia remains on the CCL for the reasons indicated 
    in the preamble to the draft CCL, including the ineffectiveness of 
    chlorination and filtration.
        The Agency recognizes that Entamoeba histolytica can be virulent. 
    Even though the commenter cites an article stating that dogs and 
    perhaps pigs may be reservoirs for E. histolytica (Benenson 1995), 
    animals are probably not major host reservoirs, in contrast to the 
    situation for Giardia and Cryptosporidium. Thus, if sewage treatment 
    practices are adequate, the potential for source water contamination is 
    probably low, as suggested by the fact that the organism has not caused 
    a significant waterborne disease outbreak since the early 1950s (the 
    one reported exception in the U.S. was a small outbreak in 1984 
    associated with untreated well water). Importantly, the cyst is large 
    (10-15m). It is slightly larger than a Giardia cyst, and much 
    larger than microsporidia spores that infect humans (1-5m) to 
    which the commenter compares E. histolytica. Thus, EPA believes that 
    regulations that control for Giardia and Cryptosporidium should also 
    control E. histolytica. For these reasons, E. histolytica was not 
    included on the final CCL. The Agency has also decided not to include 
    Isospora belli for the reasons given in the preamble of the draft CCL, 
    especially for the fact that its oocysts are 30 x 12m, larger 
    than Giardia cysts, and any rule to control Giardia and Cryptosporidium 
    should also control this organism.
    Viruses
        The draft CCL included the following viruses: caliciviruses, 
    adenoviruses, coxsackieviruses, echoviruses, and the hepatitis A virus. 
    Several commenters suggested that EPA add rotaviruses, hepatitis E 
    virus, and bacteriophage to the final CCL.
    EPA Response
        The final CCL remains the same as the draft, except that the 
    hepatitis A virus has been removed. Hepatitis A was removed because it 
    is being addressed by current regulations, or regulations under 
    development. As a matter of policy, all viruses are regulated as a 
    class under EPA's SWTR and are going to be regulated as a class under 
    the GWDR, and the Agency does not believe that additional research is 
    needed to demonstrate the efficacy of disinfection for this organism. 
    In contrast, the Agency believes that additional research is needed on 
    the impact of treatment for the other viruses that remain on the CCL.
        EPA did not include rotaviruses on the final CCL, primarily because 
    they are vulnerable to disinfection and should always be associated 
    with fecal contamination. Thus, the Agency believes that EPA's SWTR, 
    plus the upcoming GWDR, should adequately control these viruses.
        EPA excluded the hepatitis E virus from the final CCL because the 
    Agency does not regard the virus as a significant public health threat 
    in the U.S. and believes that current sewage treatment practices are 
    sufficient to eliminate significant risk of waterborne transmission. 
    EPA recognizes that hepatitis E is a major problem in some developing 
    countries, especially for pregnant women. However, there is no evidence 
    that the organism is a problem in the U.S. Rare cases have occurred in 
    the U.S., usually among travelers returning from an area where the 
    disease is endemic (Mast and Krawczynski 1996). Structurally, the 
    organism is a small, single-stranded RNA virus similar to the 
    caliciviruses, coxsackieviruses, and echoviruses, all of which remain 
    on the CCL, because of evidence of outbreaks and occurrence in finished 
    waters.
        Bacteriophage were excluded from the CCL because they are not 
    pathogenic to humans. However, EPA recognizes that they may be useful 
    as an indicator of fecal contamination. EPA has decided not to include 
    indicators of fecal contamination or of pathogens on the final CCL. 
    However, the Agency will consider indicators in the context of 
    regulations to control pathogens on the CCL. For example, the Agency is 
    considering two bacteriophage--the somatic coliphage and the male-
    specific coliphage--as an indicator of fecal contamination under the 
    Groundwater Disinfection Rule.
    Bacteria
        The draft CCL included the following bacteria: Helicobacter pylori, 
    Legionella, Mycobacterium avium complex, and Aeromonas hydrophila. 
    Commenters urged EPA to include additional bacteria, including 
    Pseudomonas aeruginosa, Shigella, Salmonella, Vibrio, Arcobacter, 
    Campylobacter, Yersinia, and E. coli O157:H7, and that if these enteric 
    bacterial pathogens were not included on the CCL, then H. pylori and A. 
    hydrophila should not be included either, because both are sensitive to 
    disinfection also.
    
    [[Page 10281]]
    
    EPA Response
        The final CCL does not include the enteric bacterial pathogens that 
    commenters suggested EPA add (Shigella, Salmonella, Vibrio, Arcobacter, 
    Campylobacter, Yersinia, and E. coli O157:H7). The Agency's reasons for 
    excluding these organisms are that they are all sensitive to 
    disinfection and are all associated with fecal contamination. Thus, EPA 
    regards total coliforms as an adequate indicator for these organisms. 
    Moreover, the SWTR requires all surface water systems to disinfect, and 
    the forthcoming GWDR is likely to require systems that have wells 
    vulnerable to fecal contamination to disinfect or provide other 
    corrective action. The Agency regards these regulatory tools as 
    sufficient to control for the above pathogens.
        With regard to P. aeruginosa, the preamble to the draft CCL 
    indicated that the participants of the EPA Drinking Water Microbiology 
    and Public Health Workshop could not agree on whether to include this 
    organism on the draft CCL. There was controversy among participants 
    about its public health significance and its potential health risk via 
    the waterborne route. Therefore, participants recommended that EPA 
    conduct a complete literature search on the topic before deciding 
    whether to include this organism on the final list. The Agency has not 
    yet completed this search. Because of this lack of information, EPA has 
    decided to defer a decision on P. aeruginosa and not include it on the 
    CCL. However, should the literature search suggest that regulatory 
    action may be necessary, EPA will increase the priority of research in 
    this area, if appropriate.
        With regard to Helicobacter, following the meeting of the panel, an 
    article was published indicating that Helicobacter is sensitive to 
    chlorine (Johnson, Rice and Reasoner 1997). However, EPA decided not to 
    remove Helicobacter from the CCL because of the large number of people 
    in the U.S. affected by peptic ulcers (about 20 million people) and 
    gastritis, the poor survival rate of individuals with gastric cancer, 
    and ignorance about the mode of transmission of the organism. 
    Helicobacter pylori has been implicated in the cause of these three 
    diseases. The Agency believes that, in spite of the recent disinfection 
    data, it would be improper to remove Helicobacter from the CCL for 
    these reasons.
        With regard to Aeromonas hydrophila, EPA recognizes that this 
    organism is sensitive to disinfection in source and finished waters. 
    However, unlike the fecal pathogens listed above, A. hydrophila  may 
    enter the distribution system either as a result of inadequate 
    treatment or a break in the water distribution system, and grow as part 
    of the biofilm on the pipes or in the sediment, which may protect it 
    from disinfectants. In addition, A. hydrophila  is not necessarily 
    associated with fecal contamination. Thus, the total coliforms rule may 
    not be adequate as an indicator for this organism. Moreover, systems 
    which are not required to disinfect (or take other corrective action) 
    under the forthcoming Groundwater Disinfection Rule because they are 
    considered not vulnerable to fecal contamination, may still be 
    vulnerable to A. hydrophila. For these reasons, EPA does not believe 
    that this organism can be treated in the same manner as E coli O157:H7 
    and other fecal bacteria listed by the commenter. Thus, the final CCL 
    includes A. hydrophila .
        EPA removed Legionella in ground water from the final CCL. It was 
    removed because: (1) the Agency intends to address the control of this 
    organism under the Groundwater Disinfection Rule, and (2) the Agency 
    does not believe that high priority research is needed in this area to 
    regulate this organism.
    Algae and Their Toxins
        Several commenters strongly urged EPA to add algae, especially the 
    blue-green algae, plus their toxins (e.g., mycotoxin) to the CCL. One 
    commenter suggested that Pfiesteria piscicida be included on the final 
    CCL, as well.
    EPA Response
        In the preamble to the draft CCL, EPA stated that certain species 
    of blue-green algae produce toxins that could be harmful if ingested at 
    high enough concentrations, but that algal control was best handled 
    through good watershed management practices. The Agency continues to 
    regard this strategy as reasonable. However, the Agency has decided to 
    add the algae and their toxins to the final CCL because: (1) pathogenic 
    algae and their toxins are not necessarily associated with fecal 
    contamination and thus may not be effectively controlled by the SWTR or 
    ESWTR, and (2) some data suggest that current treatment techniques may 
    be particularly inadequate in controlling algal toxins. Placement of 
    this group of contaminants on the CCL will make them a priority for 
    research to determine what triggers toxic algal growth in source water 
    and the effectiveness of water treatment practices.
        EPA is aware that Pfiesteria piscicida has been implicated in 
    adverse health effects in humans. Apparently at least 13 researchers 
    who worked with dilute toxic cultures of this organism and 10 fishermen 
    sustained mild to serious health effects by water contact or by 
    inhaling toxic aerosols. Symptoms include skin rashes, reddening of the 
    eyes, severe headaches, blurred vision, nausea/vomiting, breathing 
    difficulties, kidney and liver problems, short-term memory loss, 
    confusion, and other problems. The organism has a complicated life 
    cycle, with about 24 stages. Pfiesteria's habitat is estuarine or 
    brackish water. Current data indicate that, like most other 
    dinoflagellates, the organism grows poorly in fresh water and does not 
    elaborate toxins in this milieu, thus, there is no evidence that 
    Pfiesteria  occurs or could occur in drinking water. Moreover, the size 
    ranges from 5-450 m, with the dormant cyst stages 7-60 
    m in diameter. Thus filtration that is effective for removing 
    Cryptosporidium (4-6 m) should be effective for removing 
    Pfiesteria. For these reasons, EPA believes that Pfiesteria  does not 
    represent a health threat in drinking water systems, and thus did not 
    include Pfiesteria  on the final CCL.
    
    I. MTBE
    
        A number of commenters agreed with the inclusion of methyl-t-butyl 
    ether (MTBE) on the CCL, and some indicated that MTBE should be 
    included among the contaminants for which determinations will be made 
    by 2001. Another commenter suggested it should not be included on the 
    CCL but should be included in the forthcoming Unregulated Contaminant 
    Monitoring rulemaking, due in 1999.
    EPA Response
        The Agency agrees that MTBE should remain on the CCL. However, as 
    with all the contaminants on the list, EPA has not made a determination 
    with respect to regulating MTBE. Although there are serious limitations 
    in the MTBE data, there is some evidence to support a concern for 
    potential human hazard. MTBE has been found in some drinking water 
    wells but it is uncertain whether the concentrations are at levels of 
    health concern. Given the potential health hazard and need for 
    additional data, MTBE meets the criteria for placement on the CCL.
        The inclusion of a contaminant on the CCL does not mean that the 
    contaminant will be regulated. As noted earlier, contaminants on the 
    CCL include those for which the Agency must make a determination of 
    whether or not to regulate by 2001 pursuant to the requirements of the 
    SDWA, but it also includes the Agency's research
    
    [[Page 10282]]
    
    priorities, contaminants for which monitoring is necessary to gather 
    additional data. MTBE will remain on the CCL since the Agency needs 
    additional occurrence data.
        At this time, the EPA has not included MTBE among the contaminants 
    for which determinations will be made by 2001. As stated earlier, MTBE 
    needs additional health and occurrence data, and as such, it will be 
    one of the priority contaminants for which the Agency will gather such 
    data. There are no data on the effects on humans of drinking MTBE 
    contaminated water. Therefore, EPA is continuing to evaluate the 
    available health information and is doing additional research to seek 
    more definitive estimates of potential risks to humans from drinking 
    water. One of the mechanisms for gathering occurrence data is to 
    include a contaminant in the forthcoming Unregulated Contaminant 
    Monitoring rulemaking to be issued in August 1999. The Agency is also 
    not precluded from using other means of gathering occurrence data which 
    may include conducting special studies. The data collection and 
    evaluation efforts will assist in determining what the appropriate 
    action should be with respect to MTBE. Placing MTBE in this category 
    does not prevent the Agency from selecting it to make a determination 
    of whether or not to regulate by 2001; however, at this time, it is not 
    likely that the necessary data will be collected and evaluated in time 
    to make a determination by this date.
        To facilitate data collection and evaluation efforts for MTBE, an 
    Agency-wide task force has been formed and has prepared a draft 
    Oxygenates in Water Research Strategy. The Strategy identifies current, 
    or soon to be started, research in areas that include environmental 
    occurrence, source characterization, transport and transformation, 
    exposure, toxicity, and treatment. The Strategy will also identify key 
    areas of research that are still necessary to build a stronger, more 
    informed scientific database to support health risk assessment and risk 
    management decisions with respect to fuel oxygenates, including MTBE.
        On October 7, 1997, EPA convened a day-long meeting of over 50 
    experts--including representatives from industry, academia, 
    consultants, and other government agencies--to review a draft of the 
    Strategy. The information produced in this workshop is being used to 
    help revise the draft of the Strategy, which will serve as a blueprint 
    to assist in coordinating efforts by various organizations, public and 
    private, in addressing the issues related to oxygenates in water. The 
    Agency will also publish the Strategy in the Federal Register this 
    Spring, to seek additional public comment on the research priorities 
    identified.
    
    J. Organotins
    
        Four commenters argued that organotins, specifically the mono- and 
    di-organotins, the only types used as polyvinyl-chloride (PVC) heat 
    stabilizers, should not be included on the CCL. The commenters 
    maintained that, due to evidence of low toxicity and low migration 
    (thus, low risk to consumers), mono- and di-organotins, especially 
    mono- and di-methyltins, should not be of concern to drinking water, 
    particularly in light of the National Sanitation Foundation (NSF) 
    certification program for plumbing materials. Other commenters 
    indicated that it was premature for the Agency to regulate organotins, 
    but thought it prudent that the Agency keep informed of the issue.
    EPA Response
        EPA disagrees with the commenters who suggest that organotins 
    should be deleted from the CCL. It should be emphasized that retaining 
    organotins on the CCL does not necessarily mean that they will be 
    regulated. The Agency believes that organotins, including mono- and di-
    organotins which are used as heat stabilizers in PVC and chlorinated 
    polyvinyl-chloride (CPVC) pipes, are of sufficient concern to warrant 
    further investigation. The Agency is aware of the NSF certification 
    program, and has noted that many States require the use of NSF-
    certified material in the construction of new buildings. The Agency 
    agrees with the NDWAC Working Group recommendation that an assessment 
    of the toxicological data underlying the action levels established by 
    the NSF needs to be made along with assessment of other available 
    information on organotins, before these compounds can be disregarded as 
    of concern. The Agency requested this information from the NSF, and 
    learned that due to confidentiality agreement, NSF cannot disclose this 
    information, therefore we have not yet been able to assess the 
    toxicological data.
        There are numerous concerns about the occurrence and toxicological 
    significance of various species of organotins in drinking water. A 
    recent report indicates that unlike PVC systems, new CPVC systems have 
    the potential to contaminate drinking water with organotin compounds 
    for a longer period of time after installation (Forsyth and Jay 1997). 
    There has been a report concerning tributyltin contamination of 
    drinking water from PVC pipes, and tributyltin is of far more 
    toxicological significance than mono- and di-organotins (Sadiki et al, 
    1996). There is also concern about the recent reports of teratogenic 
    potential of dibutyltin (Ema et al, 1996). The Canadian Government is 
    concerned about organotin contamination of drinking water and has 
    launched a national survey.
        In view of these concerns, the Agency believes that organotins, 
    including mono- and diorganotins, should remain on the CCL until the 
    Agency can perform its own in-depth evaluation of the occurrence and 
    toxicological data of the contaminants of this class.
    
    K. Perchlorate
    
        The majority of comments on perchlorate indicated support for its 
    inclusion on the CCL. Commenters pointed out that the information on 
    the occurrence of perchlorate in drinking water supplies was sufficient 
    to raise concern over the potential impact on public health. A few 
    commenters expressed concern that perchlorate should not be regulated 
    or that there was not sufficient information at present to warrant its 
    regulation, and that a health advisory would be more appropriate.
    EPA Response
        The Agency agrees with commenters that sufficient information 
    exists to raise concern over the potential health effects and 
    occurrence of perchlorate in drinking water supplies. Despite 
    significant data gaps regarding health effects, occurrence, and 
    treatment technologies, perchlorate has been found in a number of 
    drinking water supplies at levels of health concern, and as a result is 
    included on the final CCL.
        The Agency understands that the extent of actual or even potential 
    perchlorate contamination is unclear for many parts of the country, and 
    that for some areas of the country perchlorate contamination may not be 
    an issue. However, perchlorate has been detected in a number of 
    drinking water supplies to date and warrants further evaluation. 
    Placement of perchlorate on the CCL means that the Agency will make it 
    a priority to conduct further investigation and evaluation of the 
    health effects and national occurrence of perchlorate in drinking water 
    supplies.
        Perchlorate has been placed in the categories of needing additional 
    health effects, treatment research, and occurrence information. Several 
    toxicological and occurrence studies are planned or are underway, which 
    will assist the Agency in filling these data
    
    [[Page 10283]]
    
    gaps on perchlorate. At this time, the Agency has not made a 
    determination to issue a health advisory or to regulate perchlorate. 
    The additional data obtained from these health effects and occurrence 
    studies will provide a sound scientific basis for future EPA decisions 
    of whether to regulate perchlorate or not, to prepare a health advisory 
    or guidance, or to include perchlorate in the Unregulated Contaminant 
    Monitoring rulemaking. Placing perchlorate in these categories does not 
    preclude the Agency from selecting it to make a determination of 
    whether or not to regulate by 2001, but at this time it is unlikely 
    that perchlorate will be included among those for which determinations 
    will be made by 2001.
    
    L. Rhodamine WT
    
        A few commenters argued that Rhodamine WT be removed from the CCL. 
    The commenters stated that Rhodamine WT has a very specialized purpose. 
    They also noted that it is certified by the NSF and that the 
    certification is reviewed by EPA. They also stated that data for 
    including Rhodamine WT were questionable, and that the contaminant had 
    no specific health effect.
    EPA Response
        EPA agrees with the commenters and has removed Rhodamine WT from 
    the CCL. Rhodamine WT was placed on the draft CCL because it was 
    detected in ground water above the NSF Standard 60 concentration of 
    0.1g/L for drinking water. However, three concentrations have 
    been established under the NSF Standard 60; 0.1g/L for 
    drinking water, 10g/L for water entering a drinking water 
    plant (prior to treatment and distribution), and 100 g/L for 
    ground water not associated with drinking water production. These 
    concentration values were developed under the Agency's former Additives 
    Program which was subsequently privatized and turned over to NSF in the 
    1980's.
        The maximum concentration of available occurrence data was 28 
    g/L detected in ground water, and, as such, should be compared 
    to the recommended value of 100 g/L for ground water, not the 
    value for drinking water. Given this comparison, the maximum 
    concentration of 28 g/l is well below the recommended value 
    for ground water of 100 g/L. When the NSF guidance regarding 
    the use of Rhodamine WT as a fluorescent tracer in water flow studies 
    is followed the Agency does not anticipate any adverse health effects 
    resulting from the use of Rhodamine WT.
    
    M. Sodium
    
        Many commenters were opposed to including sodium on the CCL, 
    primarily due to their contention that sodium in drinking water is not 
    a public health concern because of its extremely low level in drinking 
    water, and its small contribution to overall sodium intake. Commenters 
    also noted that controlling sodium in public water systems would be 
    cost-prohibitive and produce marginal or nonexistent health benefits. 
    Commenters argued that food, which is the major source of sodium, is 
    allowed to average 440 mg/day under a ``salt-restricted'' medically-
    supervised diet, and that controlling sodium content in food would 
    address salt-restriction more directly. Commenters also strongly 
    disagreed with the use of EPA's DWEL of 20 mg/l as the public health 
    criteria for determining whether to include sodium on the CCL. The 
    commenters mentioned a more up-to-date, 1996 report published by the 
    American Medical Association (AMA) showing a lack of association 
    between sodium and blood-pressure, except for older individuals with 
    existing hypertension. Other commenters argued for the inclusion of 
    sodium, citing studies linking it to hypertension and the need to 
    maximize protection of salt-sensitive individuals as a sensitive 
    subpopulation.
    EPA Response
        The issue of sodium posed a unique challenge for the Agency 
    priority setting and contaminant candidate listing process. Information 
    from commenters on each side made important points. On the one hand, 
    high levels of salt intake can be associated with hypertension in some 
    individuals. On the other hand, sodium levels in drinking water are 
    unlikely to be a significant contribution to adverse health effects.
        This low level of concern is compounded by the legitimate 
    criticisms of EPA's 20 mg/l guidance level that was used in this 
    process. EPA believes this guidance level for sodium needs updating, 
    and is probably low. If a health benchmark for drinking water were 
    established using current information and current drinking water health 
    assessment procedures, it would likely be higher. This revision could 
    establish a new level at which sodium occurrence would not meet the 
    criteria for inclusion on the CCL as a drinking water contaminant of 
    concern. There was insufficient time to complete a reassessment of the 
    sodium guidance in advance of the CCL issuance.
        Given the state of the data, EPA faced a dilemma on whether or not 
    to list sodium. A decision not to list would be justified by the fact 
    that much is known about sodium and it does not appear to be a drinking 
    water risk comparable to other priority contaminants. In fact, this was 
    the logic supporting the decision not to include sodium on the previous 
    drinking water priority list in 1991. However, a decision to list 
    sodium would afford EPA the opportunity to address the confusion 
    surrounding the current guidance for sodium in drinking water.
        In the end, EPA decided to include sodium on the CCL, primarily as 
    a vehicle to reexamine and correct the current, outdated guidance. 
    Therefore, sodium is listed, not as a Regulatory Determinations 
    Priority, but as a Research Priority to allow time to evaluate and 
    revise the Agency guidance. When this is completed, EPA will reevaluate 
    whether sodium merits retention on the CCL for any further action.
    
    N. Triazines
    
        Many commenters applauded EPA's intention to address triazines and 
    their metabolites as a group a ``good first step'' to addressing these 
    compounds. A number of commenters indicated that we should include 
    other triazine degradation products such as deisopropyl atrazine and 
    diaminochlorotriazine (same as diamino atrazine) because they too are 
    common degradation products of atrazine as well as simazine, and are 
    found at higher concentrations than atrazine-desethyl. Once commenter 
    expressed concern that additional information was being considered and 
    evaluated by the Agency under the OPP Special Review program, and that 
    these reviews should be completed before triazines are considered for 
    the CCL.
    EPA Response
        The Agency agrees with the points raised by the commenters 
    regarding the triazine degradation products. As a result, the EPA has 
    decided to include triazines and their degradation products (including 
    but not limited to: cyanazine and atrazine-desethyl) on the CCL as a 
    group to include all potential risks from this class of compounds. 
    Stakeholders, through the regulatory reassessment process in developing 
    the redirection strategy, and through the development of this draft 
    CCL, have requested that the Agency address triazine pesticides as a 
    group, which includes all parent and degradate compounds, as opposed to 
    each triazine as an individual contaminant.
        The EPA has been studying the mechanism of carcinogenicity of this
    
    [[Page 10284]]
    
    group of analogues along with their degradation products, and will 
    continue to study these chemicals as a group to characterize their risk 
    in drinking water. The Agency regulated atrazine in 1991 and simazine 
    in 1992. The Agency may ultimately develop regulations for the mixtures 
    of triazines either through the revision of existing regulations or the 
    development of new ones.
        EPA disagrees with the notion that triazines should be excluded 
    from the CCL until after the completion of the Special Reviews. The 
    triazines are included in the Priority Group 1 of pesticide tolerances 
    that will be examined first under the Food Quality Protection Act 
    (FQPA) tolerance reassessment (62 FR 42020). The work being 
    accomplished by OPP in their review efforts will certainly be factored 
    into EPA's decisions regarding triazines, as with all pesticides on the 
    CCL.
    
    O. Zinc
    
        Two commenters were opposed to the inclusion of zinc on the CCL. 
    The commenters argued that zinc did not meet the criteria for inclusion 
    on the CCL, and is generally non-toxic to animals and humans. They 
    pointed out that zinc is used in a wide variety of products, and is 
    also an essential element. One commenter stated that the Agency had not 
    considered zinc's beneficial qualities when deciding whether it should 
    be included on the CCL, and that the WHO and EPA have both stated that 
    deficiency of zinc is more of a concern than over-exposure. The 
    commenter further argued that the history of the substitution from the 
    1988 DWPL was not considered, and that the HA value used in the 
    Agency's analysis was from a ``7-yr old draft'' which was not available 
    for comment and therefore the explanation behind the Agency's HAL of 
    2,000 g/l was not available for comment.
    EPA Response
        The EPA agrees with the commenter on the point raised that zinc 
    does not meet the criteria for inclusion on the CCL, and has removed 
    zinc from the CCL. The Agency has determined that the number of public 
    water systems with zinc levels above 1,000 g/l is 4, and none 
    had occurrence levels above 2,000 g/l, and, as a result, zinc 
    doesn't meet the criteria for inclusion on the CCL. The criterion for a 
    contaminant to be included on the CCL was ``occurrence at the health 
    level of concern in 10 or more small public water systems.'' The action 
    of removing zinc from the CCL was due to its lack of occurrence in 
    water systems at health levels of concern, not due to its lack of 
    toxicity. It is known that daily exposure to zinc of approximately 60 
    mg/l (60,000 g/l) or more can effect copper metabolism, and 
    result in deleterious health effects.
    
    IV. Continuing Work in Preparation for Future CCLs
    
        In the Federal Register notice on the draft CCL, the Agency 
    deferred action on a number of pesticides, and contaminants implicated 
    as endocrine disruptors, in anticipation of impending resolution 
    specific to these two groups of contaminants. Action on these 
    contaminants continues to be deferred and these contaminants will be 
    reconsidered when the next CCL is developed. The Agency is also 
    resuming work on a contaminant identification process to be used in the 
    development of future CCLs. Further discussion of these three topics 
    follows.
    
    A. Pesticides Deferred
    
        In developing the CCL, the SDWA requires EPA to consider substances 
    registered as pesticides under FIFRA. During the development of the 
    CCL, the Agency's Office of Ground Water and Drinking Water sought 
    assistance from OPP in determining what pesticides should be priorities 
    for the drinking water program. In response to the request, OPP 
    provided recommendations for a number of pesticides based on physical-
    chemical properties, occurrence and extent of use, using the Ground 
    Water (GW) Risk score. The GW-Risk score is a calculated potential of 
    pesticides to leach to ground water. Pesticides with a GW-Risk of 2.0 
    or greater were included for initial consideration in developing the 
    draft CCL.
        However, later during the data evaluation and screening phase of 
    the CCL development, the decision was made to defer pesticides 
    identified by the GW-Risk of 2.0 or greater for which no additional 
    information was available. Inclusion on the CCL would be deferred 
    pending further evaluation of the potential of these pesticides to 
    occur at levels of health concern. The Agency is working to develop a 
    tool to estimate concentrations in ground and surface waters based on 
    physical-chemical properties and pesticide use volumes, and will then 
    compare the estimated concentrations with health advisory levels or 
    calculated health levels based on reference doses or cancer potency.
        It was anticipated that the tool to estimate concentrations of 
    pesticides in ground and surface waters would be completed and 
    available in time to reevaluate the inclusion of the additional 
    pesticides prior to completing the CCL. However, the Agency believes it 
    is important to have this tool peer-reviewed prior to its use, which 
    would increase the time necessary for its development beyond the time 
    available. Therefore, EPA did not attempt to complete this work before 
    finalizing the CCL in today's notice. As a result, action on these 
    pesticides remains deferred until the next CCL.
        On December 10, 1997, the Science Advisory Panel (SAP) met to 
    discuss drinking water exposure assessment issues with the OPP. The 
    objective of the meeting was to obtain SAP's recommendation on the 
    approaches and models developed by OPP to determine short-term and 
    long-term potential exposures from pesticides in drinking water. The 
    issues of monitoring requirements, and assessing impacts of exposure to 
    mixtures were also part of the discussion. The approaches and models 
    developed by OPP and the forthcoming SAP's recommendations on these 
    issues are of particular importance to the Office of Water in that the 
    outcome will be used in the drinking water program as well.
    
    B. Endocrine Disruptors
    
        During the development of the draft CCL, the Agency initially 
    considered, then later deferred, a number of contaminants implicated or 
    suspected as substances which disrupt the function of the endocrine 
    system. As stated in the notice of the draft CCL, EPA issued an interim 
    assessment in February 1997, pending a more extensive review expected 
    to be issued by the National Academy of Sciences (NAS), determining 
    that, while effects have been found in laboratory animal studies, a 
    causal relationship between exposure to a specific environmental agent 
    and an adverse health effect in humans operating via endocrine 
    disruption has not been established, with a few exceptions. Further 
    research is needed before such effects can be demonstrated.
        Under the SDWA, as amended, the Agency is also required to 
    establish a program to screen endocrine disrupting contaminants. 
    Additional authority to assess endocrine disruptors is also provided 
    through the recently enacted FQPA. EPA's Office of Prevention, 
    Pesticides, and Toxic Substances (OPPTS) has the Agency lead on 
    endocrine disruptor screening and testing issues, and is actively 
    engaged in research and regulatory initiatives to respond to the 
    growing scientific and public concern over endocrine disruptors. Also, 
    the Endocrine Disruptor Screening and Testing Advisory Committee 
    (EDSTAC) has
    
    [[Page 10285]]
    
    been established to provide advice and counsel to the Agency in 
    implementing a screening and testing strategy required under the FQPA 
    and SDWA. EDSTAC will complete its recommendations for a screening and 
    testing strategy by March 1998. The recommendations will be peer-
    reviewed jointly by the SAB and the FIFRA SAP.
        As a result, pending completion of the EDSTAC's recommendations and 
    the additional review of endocrine disruptors by the NAS, EPA has not 
    included contaminants for inclusion on this first CCL based solely on 
    the possibility of endocrine disruption (although several contaminants 
    implicated as endocrine disruptors were considered for other reasons). 
    As stated in the notice on the draft CCL, the Agency will continue to 
    follow this issue closely and reconsider this category of potential 
    contaminants in the development of future CCLs.
    
    C. Development of the Contaminant Selection Process
    
        This CCL is largely based on knowledge acquired over the last few 
    years and other readily available information, but an enhanced, more 
    robust approach to data collection and evaluation will be developed for 
    future CCLs. The Agency will also resume work on the contaminant 
    identification and the contaminant selection process. The CCL, and the 
    identification and selection process will serve as the cornerstones of 
    the Agency's regulatory development process. In addition to developing 
    the CCL, and the identification and selection process, the Agency 
    intends to obtain resources in order to acquire better data and 
    information, improve analytical capability, and seek additional 
    stakeholder involvement.
        The next steps for improving the contaminant identification and 
    selection process include an American Water Works Association Research 
    Foundation (AWWARF) project utilizing a series of workshops in which 
    established decision-making tools would be employed to develop a 
    process to identify emerging pathogens of concern for consideration, 
    regulation, and future research. The work is expected to begin in June/
    July 1998. A project with the NAS will also be undertaken to solicit 
    input on criteria for listing and selecting chemical contaminants for 
    future CCLs. A panel is currently being formed and work is expected to 
    begin in summer of 1998. The development of the identification and the 
    selection process will be completed in consultation with the NDWAC and 
    the Working Group on Occurrence & Contaminant Selection, and their 
    future involvement is likely to include reviewing products from AWWARF 
    and NAS in 1999. The CCL is a critical input to shaping the future 
    direction of the drinking water program, and improvements to the 
    process will be made with each successive cycle of publishing the list.
    
    V. Data, Research Needs and Next Steps
    
        Table 2 divides the CCL into categories to represent the next steps 
    and data needs for each contaminant. Sufficient data are needed to 
    conduct analyses on extent of exposure and risk to populations via 
    drinking water in order to determine appropriate Agency action 
    (development of health advisories, or regulations, or no action) for 
    many of these contaminants. If sufficient data are not available, they 
    must be obtained before such an assessment can be made. The data and 
    information required will be gathered by research or monitoring 
    programs, and are not likely to be available for analyses to be 
    completed prior to 2001. Thus, the contaminants for which sufficient 
    data exist at the time of publishing the CCL are likely to be those 
    from which the determinations will be made by 2001.
        However, it should be noted that the groupings in Table 2 are based 
    on current information, and some movement of contaminants between 
    categories can be expected as more information is evaluated and 
    analyzed. The Regulatory Determination Priorities category in Table 2 
    will be used to select 5 or more contaminants for which the Agency must 
    determine, by August 2001, whether or not regulations should be 
    developed. To make these determinations, further analysis of data 
    currently available, or data that will become available within a short 
    period, is required to prepare supporting documents addressing health 
    criteria, cost and benefit assessments, and analyses of analytical 
    methods, occurrence, and treatment technology and feasibility. For 
    contaminants in the category, there may also be some short-term 
    research needs, such as bench-scale treatability studies, that must 
    also be completed. The next steps for the Agency regarding the 
    contaminants in this category are to determine which contaminants to 
    address first, and outline plans of action to work towards making 
    determinations for five or more by August 2001.
        The contaminants in the Research Priorities category have 
    significant data gaps in areas of health, treatment, or analytical 
    methods. For these contaminants, the research, or data gathering, and 
    subsequent analysis needed are not expected to be complete within the 
    3\1/2\ years, by August 2001, in order to make determinations of 
    whether regulation of these contaminants is necessary. These are EPA's 
    priority contaminants for research and data gathering. Some of these 
    research needs are currently being addressed by EPA or other agencies 
    (e.g., Department of Defense for perchlorate), while other needs are 
    newly identified.
        The contaminants in the Occurrence Priorities category have 
    significant data gaps in occurrence data. The Unregulated Contaminant 
    Monitoring Regulations (UCMR) will be the primary source for data for 
    most contaminants included in this category; however, some contaminants 
    may be more appropriate for special studies or surveys, or joint data 
    gathering efforts with other Agencies. Also, for some contaminants, 
    suitable analytical methods must be developed prior to obtaining the 
    occurrence data necessary.
        The next steps for the Agency are to develop short- and long-term 
    research plans on health, treatment, and methods, to develop the UCMR 
    proposal (expected August 1998) for gathering occurrence data, and to 
    plan for special occurrence studies, where appropriate. The Agency will 
    also use its FIFRA and Toxic Substances Control Act (TSCA) authorities, 
    as appropriate, to conduct studies and obtain data necessary for 
    decision-making.
    
    [[Page 10286]]
    
    
    
                                            Table 2.--Next Steps for the CCL                                        
    ----------------------------------------------------------------------------------------------------------------
                                                   Research priorities                                              
          Regulatory      ---------------------------------------------------------------------      Occurrence     
        determination                                                      Analytical methods        priorities     
          priorities          Health research       Treatment research          research                            
    ----------------------------------------------------------------------------------------------------------------
    Acanthamoeba           Aeromonas hydrophila   Adenoviruses           Adenoviruses           Adenoviruses.*      
     (guidance)            Cyanobacteria (Blue-   Aeromonas hydrophila   Cyanobacteria (Blue-   Aeromonas           
    1,1,2,2-                green algae), other   Cyanobacteria (Blue-    green algae), other    hydrophila.        
     tetrachloroethane      freshwater algae,      green algae), other    freshwater algae,     Cyanobacteria (Blue-
    1,1-dichloroethane      and their toxins       freshwater algae,      and their toxins       green algae), other
    1,2,4-                 Caliciviruses           and their toxins      Caliciviruses           freshwater algae,  
     trimethylbenzene      Helicobacter pylori    Caliciviruses          Helicobacter pylori     and their toxins.* 
    1,3-dichloropropene    Microsporidia          Coxsackieviruses (ICR  Microsporidia          Caliciviruses.*     
    2,2-dichloropropane    Mycobacterium avium     data)                 1,2-diphenylhydrazine  Coxsackieviruses    
    Aldrin                  intercellulare (MAC)  Echoviruses (ICR       2,4,6-trichlorophenol   (ICR data).        
    Boron                  1,1-dichloropropene     data)                 2,4-dichlorophenol     Echoviruses (ICR    
    Bromobenzene           1,3-dichloropropane    Helicobacter pylori    2,4-dinitrophenol       data).             
    Dieldrin               Aluminum               Microsporidia          2-methyl-Phenol        Helicobacter        
    Hexachlorobutadiene    DCPA mono-acid & di-   Mycobacterium avium    Acetochlor              pylori.*           
    p-Isopropyltoluene      acid degradates        intracellulare (MAC)  Alachlor ESA           Microsporidia.*     
    Manganese              Methyl bromide         Aluminum               Fonofos                1,2-                
    Metolachlor            MTBE                   MTBE                   Perchlorate             diphenylhydrazine.*
    Metribuzin             Perchlorate            Perchlorate            RDX                    2,4,6-              
    Naphthalene            Sodium (guidance)                                                     trichlorophenol.*  
    Organotins                                                                                  2,4-dichlorophenol.*
    Triazines &                                                                                 2,4-dinitrophenol.* 
     degradation products                                                                       2,4-dinitrotoluene. 
     (incl., but not                                                                            2,6-dinitrotoluene. 
     limited to Cyanazine                                                                       2-methyl-phenol.*   
     and atrazine-                                                                              Alachlor ESA* and   
     desethyl)                                                                                   Acetochlor.*       
    Sulfate                                                                                     DCPA mono-acid & di-
    Vanadium                                                                                     acid degradates.   
                                                                                                DDE.                
                                                                                                Diazinon.           
                                                                                                Disulfoton.         
                                                                                                Diuron.             
                                                                                                EPTC.               
                                                                                                Fonofos.*           
                                                                                                Linuron.            
                                                                                                Molinate.           
                                                                                                MTBE.               
                                                                                                Nitrobenzene.       
                                                                                                Perchlorate.*       
                                                                                                Prometon.           
                                                                                                RDX.*               
                                                                                                Terbacil.           
                                                                                                Terbufos.           
    ----------------------------------------------------------------------------------------------------------------
    The groupings in Table 2 are based on current information, and some movement of contaminants between categories 
      can be expected as more information is evaluated and analyzed. *Suitable analytical methods must be developed 
      prior to obtaining occurrence data.                                                                           
    
    VI. Other Requirements
    
        The CCL is a notice and not a regulatory action; therefore, the 
    following statutes and executive orders are not applicable at this 
    time: the Regulatory Flexibility Act, Small Business Regulatory 
    Enforcement Fairness Act, Paperwork Reduction Act, Unfunded Mandates 
    Reform Act; and Executive Order 12866. For any contaminants selected 
    for rule-making, all necessary analysis will be conducted in accordance 
    with the rule-making process.
        Executive Order 13045, Protection of Children from Environmental 
    Health Risks and Safety Risks, requires that Federal Agencies identify 
    and assess health risks and safety risks that disproportionately affect 
    children, and ensure that its policies, programs, activities, and 
    standards address disproportionate health and safety risks to children. 
    The SDWA also requires the Agency to select priorities for regulation 
    while considering risks to sensitive subpopulations, such as infants 
    and children.
        The impact on sensitive populations will be addressed in the 
    contaminant selection process, and will be a component of the Agency's 
    determination of whether or not to regulate a given contaminant. In 
    preparation for addressing the issues of sensitive subpopulations, the 
    Agency is sponsoring several activities to determine water intake by 
    age group, by demographic distribution, and by innate or developed 
    sensitivity to potential drinking water contaminants. The Agency is 
    also collaborating with the Center for Disease Control and Prevention 
    on a study of six major cities to determine the most sensitive 
    populations for drinking water manifested during major outbreaks of 
    illness from incidents of water. Other research also is underway to 
    determine the extent of vulnerable populations including children and 
    the immunologically impaired.
    
    VII. References
    
    Benenson, A.S. 1995. Control of Communicable Diseases Manual (16th 
    ed.). pp. 10-13. American Public Health Assoc., Washington.
    Ema, M., R. Kurosaka, H. Amano, and Y. Ogawa. 1996. Comparative 
    Developmental Toxicity of Di-, Tri-and Tetrabutyltin Compounds after 
    Administration during Late Organogenesis in Rats. J. Appl. Toxicol., 
    16(1), 71-76.
    Forsyth, D.S., and B. Jay. 1997. Organotin Leachate in Drinking 
    Water from Chlorinated Polyvinyl Chloride (CPVC) Pipe. Appl. 
    Organometallic Chem., 11:551-558.
    Johnson, C.H., E.W. Rice and D.J. Reasoner. 1997. Inactivation of 
    Helicobacter pylori by chlorination. Appl. Environ. Microbiol. 
    63:4969-4970.
    
    [[Page 10287]]
    
    Mast, E.E., and K. Krawczynski. 1996. Hepatitis E: An Overview. 
    Annual Rev. Med. 47:257-266.
    Midgley, J.P., A.G. Matthew, C.M.T. Greenwood, and A.G. Logan. 1996. 
    Effect of Reduced Dietary Sodium on Blood Pressure. J. Amer. Med. 
    Assoc., 275 (20): 1590-1597.
    RDA. 1989. Recommended Dietary Allowances, tenth edition. National 
    Research Council, National Academy Press, Washington, D.C., 284 pp.
    Sadiki, Abdel-Iiah, D. Williams, R. Carrier and B. Thomas. 1996. 
    Pilot study of the Contamination of Drinking Water by Organotin 
    Compounds from PCV Materials. Chemosphere, 32:2389-2398.
    U.S. EPA. 1995. ``Acetone; Toxic Chemical Release Reporting; 
    Community Right-to-Know, Final Rule,'' 60 FR No. 116, 31643-31646, 
    June 16.
    U.S. EPA. 1996. ``Drinking Water Program Redirection Strategy,'' 
    Office of Water. EPA 810-R-96-003, June.
    U.S. EPA. 1997. ``Announcement of the Draft Drinking Water 
    Contaminant Candidate List; Notice,'' 62 FR No. 193 52194-52219, 
    October 6.
    U.S. EPA. 1998. ``Response to Comment Document.'' Office of Ground 
    Water and Drinking Water.
    
    (Authority: 42 U.S.C. 300f-300j-25)
    
        Dated: February 6, 1998.
    Robert Perciasepe,
    Assistant Administrator, Office Water, Environmental Protection Agency.
    [FR Doc. 98-5313 Filed 2-27-98; 8:45 am]
    BILLING CODE 6560-50-P
    
    
    

Document Information

Published:
03/02/1998
Department:
Environmental Protection Agency
Entry Type:
Notice
Action:
Notice.
Document Number:
98-5313
Pages:
10274-10287 (14 pages)
Docket Numbers:
W-97-11, FRL-5972-5
PDF File:
98-5313.pdf