[Federal Register Volume 62, Number 193 (Monday, October 6, 1997)]
[Notices]
[Pages 52194-52219]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-26433]
[[Page 52193]]
_______________________________________________________________________
Part III
Environmental Protection Agency
_______________________________________________________________________
Announcement of the Draft Drinking Water Contaminant Candidate List;
Notice
Federal Register / Vol. 62, No. 193 / October 6, 1997 / Notices
[[Page 52194]]
ENVIRONMENTAL PROTECTION AGENCY
[FRL-5904-7]
Announcement of the Draft Drinking Water Contaminant Candidate
List
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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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 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. Today's notice announces the draft CCL, provides background on
how it was developed, and seeks comment on various aspects of
developing the final CCL. The CCL will be the source of priority
contaminants for drinking water research, monitoring, guidance
development, and for selection of candidates for drinking water
regulation. The draft CCL includes 58 chemical and 13 microbiological
contaminants.
DATES: Submit comments on or before December 5, 1997.
ADDRESSES: Send written comments to the Comment Clerk, docket number W-
97-11, Water Docket (MC4101), USEPA, 401 M. St., SW, Washington, DC
20460. Please submit an original and three copies of your comments and
enclosures (including references). Comments must be received or
postmarked by midnight December 5, 1997.
Commenters who want EPA to acknowledge receipt of their comments
should enclose a self-addressed, stamped envelope. No facsimiles
(faxes) will be accepted. Comments may also be submitted electronically
to ow-docket@epamail.epa.gov. Electronic comments must be submitted as
an ASCII file avoiding the use of special characters and any form of
encryption. Electronic comments must be identified by the docket number
W-97-11. Comments and data will also be accepted on disks in
WordPerfect in 5.1 format or ASCII file format. Electronic comments on
this notice may be filed online at many Federal Depository Libraries.
The full record for this notice has been established under docket
number W-97-11, and includes supporting documentation as well as
printed, paper versions of electronic comments. The full record is
available for inspection from 9 to 4 p.m. Monday through Friday,
excluding legal holidays at the Water Docket, Room M2616, Headquarters,
USEPA, 401 M. Street, SW, Washington, DC. For access to docket
materials, please call 202/260-3027 to schedule an appointment.
Additionally, a few critical pieces of the record have been made
available at each Regional Office.
FOR FURTHER INFORMATION CONTACT: For general information, please
contact the EPA Safe Drinking Water Hotline. The toll-free number is
800-426-4791. For specific information on the CCL 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, DC 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. 345 Courtland Street, NE, Atlanta GA 30365. 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:
Table of Contents
I. Background
II. Draft Drinking Water Contaminant Candidate List
Table 1. Draft Drinking Water Contaminant Candidate List
III. Identification of Contaminants for the Draft Drinking Water
Contaminant Candidate List
A. Role of NDWAC Working Group
B. Microbiological Contaminants Identified for the Draft CCL
Table 2. Initial List of Microorganisms Developed by EPA for
Consideration by the Workshop on Microbiology and Public Health
1. Protozoa
2. Viruses
3. Bacteria
4. Microbiological Indicators
5. Future Activities Planned for Microbiological Contaminants
and the CCL
6. Possible Impacts From Other Regulatory Activity
C. Chemical Contaminants Identified for the Draft CCL
1. The Initial List of Chemical Contaminants Considered
Table 3. Initial List of Chemical Contaminants Considered during
Development of the Draft CCL
a. 1991 Drinking Water Priority List
b. Health Advisories
c. Integrated Risk Information System
d. Non-Target Analytes in Public Water Supply Samples
e. CERCLA Priority List
f. Stakeholder Responses
g. Toxic Release Inventory
h. Pesticides Identified by Office of Pesticide Programs
Table 4. Pesticides Deferred
i. Safe Drinking Water Hotline
Table 5. Contaminants Identified by the Safe Drinking Water
Hotline
j. Endocrine Disruptors
Table 6. Contaminants Identified as Suspected of Endocrine
Disruption
2. Development and Application of the Criteria
a. Criteria for Occurrence
b. Criteria for Health
3. Additional Specific Contaminants Included
a. Aldicarb, Aldicarb sulfoxide, and Aldicarb sulfone
b. Nickel
c. Sulfate
IV. Contaminants on the CCL Which Are of Specific Interest
A. Aluminum
B. MTBE
C. Organotins
D. Rhodamine WT
E. Sodium
F. Zinc
G. 2,6-di-tert-butyl-p-benzoquinone (DTBB)
H. Contaminants to be Considered as Groups
I. Contaminants for Which Unregulated Contaminant Data are or
Will Be Available
Table 7. Contaminants with Unregulated Contaminant Monitoring
Data
V. Request for Comment
A. Data and Research Needs
Table 8. Data Needs for Chemical Contaminants Included on the
Draft CCL
B. Perchlorate
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VI. Development of the final Drinking Water Contaminant Candidate
List, the Contaminant Identification Method, and the Contaminant
Selection Process
VII. Summary of Other Related Activity Required by the SDWA
A. Contaminant Selection and Regulatory Determination
B. The National Contaminant Occurrence Database
C. Unregulated Contaminant Monitoring Regulation
VIII. Summary of Concurrent Regulatory Activity Required by the SDWA
A. Radon
B. Other Radionuclides
C. Arsenic
D. Sulfate
E. Disinfectants and Disinfection Byproducts
IX. Other Requirements
X. References
Abbreviations Used in this Notice
ACWA-Association of California Water Agencies
ATSDR--Agency of Toxic Substances and Disease Registry
AWWARF--American Water Works Association Research Foundation
CASRN--Chemical Abstract Services Registry Number
CCL--Contaminant Candidate List
CDC-Center for Disease Control and Prevention
CERCLA--Comprehensive Environmental Response, Comprehensive and
Liability Act
CIM--Contaminant Identification Method
D/DBP--Disinfectants and Disinfection Byproducts
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
GW--Ground Water
HA--Health Advisory
HSDB--Hazardous Substances Data Base
IARC--International Agency for Research on Cancer
ICR--Information Collection Request
IESWTR--Interim Enhanced Surface Water Treatment Rule
IRIS--Integrated Risk Information System
LTESWTR--Long-term Enhanced Surface Water Treatment Rule
MCL--Maximum Contaminant Level
MCLG--Maximum Contaminant Level Goal
NAS--National Academy of Sciences
NCOD--National Contaminant Occurrence Database
NDWAC--National Drinking Water Advisory Council
NIPDWR--National Interim Primary Drinking Water Regulations
NPDWR--National Primary Drinking Water Regulations
NPL--National Priority List
NRC--National Research Council
OGWDW--EPA's Office of Ground Water and Drinking Water
OPP--EPA's Office of Pesticide Programs
OPPTS--EPA's Office of Pollution Prevention and Toxic Substances
PWS--Public Water Systems
RDA--Recommended Daily Allowance
RfD--Reference Dose
RQ--Reportable Quantity
SAB--EPA's Science Advisory Board
SDWA--Safe Drinking Water Act
STORET--Storage and Retrieval Database
SWTR--Surface Water Treatment Rule
TRI--Toxic Release Inventory
WHO--World Health Organization
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 regulations under the SDWA (section
1412(b)(1)). The SDWA, as amended, specifies that EPA must publish this
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 publish a CCL every five years thereafter. The SDWA
also 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).
Prior to the 1996 Amendments, the SDWA required the EPA to publish
a drinking water priority list (DWPL) of contaminants every three years
which were known or anticipated to occur in drinking water and which
may have required regulation under the SDWA. In response to these
previous amendments, EPA published two DWPLs which served as candidates
for regulation. The first DWPL was published on January 22, 1988 (53 FR
1892), and the second was published on January 14, 1991 (56 FR 1470).
The 1996 Amendments to the SDWA were developed and enacted during
the time of the Presidential initiative intended to substantially
improve the existing regulatory system to move the Nation toward a new
and better environmental management system for the 21st century. During
the two-year period prior to the 1996 Amendments, EPA developed a
National Drinking Water Program Redirection Strategy (EPA, 1996a) to
(1) establish priorities for setting safety standards based on health
risks and sound science; (2) support strong, flexible partnerships
among EPA, States, local governments and other stakeholders to protect
public health; and (3) promote effective community-based source water
protection. The Redirection Strategy provides an overall framework for
the development of the CCL, as well as for other drinking water program
activities.
The Agency believes the draft CCL presented in today's notice is
the result of a commendable effort of screening a larger set of
contaminants to the subset of those of most concern. The draft CCL is a
first step toward improving risk assessment, strengthening science and
data, and achieving better decision-making and future priority setting.
Today's notice announces the draft CCL, provides background on how it
was developed, summarizes detailed material available in the docket and
used to develop the list, seeks comment on the methods used to develop
the draft CCL, and seeks comment on developing the final CCL. The draft
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
redirection strategy.
Today's notice is being published pursuant to the requirement in
section 1412(b)(1) that the CCL be subjected to prior notice and
opportunity for public comment. The contaminants included are not
subject to any proposed or promulgated national primary drinking water
regulation,1 are known or anticipated to occur in public
water systems, and may require regulations under the SDWA. During the
development of the draft CCL, the Agency consulted with stakeholders,
including the National Drinking Water Advisory Council's Working Group
on Occurrence & Contaminant Selection, which includes microbiologists,
toxicologists, public health scientists, and engineers, and with other
members of the scientific community including the Science Advisory
Board (SAB). The Agency plans for a more in-depth consultation with the
SAB during the
[[Page 52196]]
fall of 1997. The occurrence database, which is to be established under
section 1445(g) by August 1999, was not considered since it is
currently under development; however, occurrence data from other
sources was considered.
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\1\ With the exception of nickel, aldicarb and its degradates,
and sulfate, which are considered special cases. Refer to later
sections of this notice for rationale for inclusion.
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The final CCL, after publication in February 1998, will be the
source of priority contaminants for the Agency's drinking water
program. Priorities for drinking water research, occurrence monitoring,
guidance development, including the development of health advisories,
will be drawn from the CCL. The CCL will also serve as the list of
contaminants from which the Agency will make determinations of whether
or not to regulate specific contaminants. This first 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.
II. Draft Drinking Water Contaminant Candidate List
The following table includes the contaminants, microbiological and
chemical, presented as the draft Drinking Water Contaminant Candidate
List. The contaminants were identified as described by Section III of
today's notice. The contaminants in the table are identified by name
and Chemical Abstracts Service Registry Number (CASRN). The draft CCL
includes 58 chemical contaminants/contaminant groups and 13
microbiological contaminants.
Table 1.--Draft Drinking Water Contaminant Candidate List
------------------------------------------------------------------------
Chemical contaminants CASRN
------------------------------------------------------------------------
1,1,2,2-tetra-chloroethane................................. 79-34-5
1,2,4-trimethylbenzene..................................... 95-63-6
1,1-dichloro-ethane........................................ 75-34-3
1,1-dichloro-propene....................................... 563-58-6
1,2-diphenylhydrazine...................................... 122-66-7
1,3-dichloropropane........................................ 142-28-9
1,3-Dichloropropene (telone or 1,3-D)...................... 542-75-6
2,4,6-trichlorophenol...................................... 88-06-2
2,2-dichloro-propane....................................... 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
2,6-di-tert-butyl-p-benzoquinone (DTBB).................... 719-22-2
2-methyl-Phenol (o-cresol)................................. 95-48-7
Acetochlor................................................. 34256-82-1
Acetone.................................................... 67-64-1
Alachlor ESA (a degradation product of alachlor)
Aldicarbs*
Aldrin..................................................... 309-00-2
Aluminum................................................... 7429-90-5
Atrazine-desethyl, a degradation product of triazines...... 6190-65-4
Boron...................................................... 7440-42-8
Bromobenzene............................................... 108-86-1
Cyanazine.................................................. 21725-46-2
p-Cymene (p-isopropyltoluene).............................. 99-87-6
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
Dimethoate................................................. 60-51-5
Disulfoton................................................. 298-04-4
Diuron..................................................... 330-54-1
EPTC (s-ethyl-dipropylthiocarbamate)....................... 759-94-4
Fonofos.................................................... 944-22-9
Hexachloro-butadiene....................................... 87-68-3
Isopropylbenzene (cumene).................................. 98-82-8
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
Nickel*
Nitrobenzene............................................... 98-95-3
Organotins
Prometon................................................... 1610-18-0
RDX........................................................ 121-82-4
Rhodamine WT
Sodium..................................................... 7440-23-5
Sulfate*
Terbacil................................................... 5902-51-2
Terbufos................................................... 13071-79-9
Vanadium................................................... 7440-62-2
Zinc....................................................... 7440-66-6
Microbiological Contaminants:
Acanthamoeba (guidance expected for contact lens wearers).............
Adenoviruses..........................................................
Aeromonas hydrophila..................................................
Caliciviruses.........................................................
Coxsackieviruses......................................................
Cyclospora cayetanensis...............................................
Echoviruses...........................................................
Helicobacter pylori...................................................
Hepatitis A virus.....................................................
Legionella (in ground water)..........................................
Microsporidia (Enterocytozoon & Septata)..............................
Mycobacterium avium intracellulare (MAC)..............................
Toxoplasma gondii.....................................................
------------------------------------------------------------------------
*Included on the CCL as special cases, not subject to the criteria used
to identify other contaminants.
III. Identification of Contaminants for the Draft Drinking Water
Contaminant Candidate List
Drinking water contamination generally occurs from: (1)
Contaminants that find their way into drinking water sources from
industrial waste releases, agricultural runoff, atmospheric deposition,
and other pollution sources; (2) contaminants formed during the
treatment of water supplies (e.g., disinfection by-products); and (3)
materials used for treatment, storage, and distribution of water. EPA
has considered all of these sources in identifying microbiological and
chemical contaminants for this draft CCL. Figure 1 provides a graphical
representation of how today's draft CCL was developed.
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The National Drinking Water Advisory Council's (NDWAC) Working
Group on Occurrence & Contaminant Selection played an integral part in
the development of the CCL by providing recommendations for the
criteria, and the contaminants for initial consideration. Also, during
the development of the CCL, the Agency sought the expertise of
microbiologists for input on microorganisms to include on the CCL. The
following sections describe the role of the NDWAC Working Group and
describe the approach used to develop the CCL for microorganisms and
chemical contaminants.
A. Role of NDWAC Working Group
After enactment of the recent SDWA amendments, and in keeping with
the redirection strategy, EPA held its first stakeholder meeting on
approaches to developing CCLs on December 2 and 3, 1996 in Washington,
D.C. Participants, including public water system professionals, state
regulatory officials, public health officials, environmental groups and
other stakeholders, with a range of interests, explored issues
concerning the identification of potential drinking water contaminants
for consideration for the first CCL as well as the factors to consider
for future CCL development. One result of the meeting was the
recommendation that the February 1998 CCL be the first topic addressed
by the NDWAC Working Group on Occurrence & Contaminant Selection.
In 1975, pursuant to the SDWA [Section 1446(a)], NDWAC was
established under the Federal Advisory Committee Act to provide
practical and independent advice, consultation, and recommendations to
EPA on the activities, functions and policies related to the SDWA. At
its meeting held on November 13 and 14, 1996, NDWAC decided that
working groups should be formed on the following subjects: Small
Systems Capacity Building; Operator Certification; Source Water
Protection; Consumer Confidence Reports; Drinking Water State Revolving
Fund; and Occurrence & Contaminant Selection. The NDWAC Occurrence &
Contaminant Selection Working Group has been integral to developing the
criteria and identifying contaminants for the draft CCL published
today.
At the recommendation of the Working Group, the Agency sought
expertise on microbiological contaminants and convened a workshop of
microbiologists. The input from the workshop was adopted by the Working
Group for use in developing the draft CCL. The approach used to
identify microorganisms for the CCL is explained in more detail in
section III.B.
In addition to microorganisms, the Working Group developed
recommendations on chemical contaminants. The recommendations addressed
which contaminants to include for initial consideration, and the
criteria for use in determining which contaminants should be included
on the draft CCL. The recommendations were developed over a series of
meetings with the Working Group followed by the endorsement by the full
NDWAC. The details concerning the contaminants included for initial
consideration, and development and use the identification criteria are
contained in section III.C.
B. Microbiological Contaminants Identified for the Draft CCL
On May 20-21, 1997, EPA utilized a workshop on microbiology and
public health to develop a list of pathogens for possible inclusion on
the first CCL. Taking part in this workshop were invited experts
representing academia, EPA and other federal agencies, and the water
industry. In preparation, EPA scientists prepared and distributed a
list of microorganisms for initial consideration by workshop members
(see Table 2.). Inclusion of organisms on this initial list was based
on disease outbreak data, published literature documenting the
occurrence of known or suspected pathogens in water, and other
information. A summary of the workshop proceedings is in the docket.
Table 2. Initial List of Microorganisms Developed by EPA for
Consideration by the Workshop on Microbiology and Public Health
Protozoa
Microsporidia
Toxoplasma
Cyclospora
Acanthamoeba
Naegleria
Isospora
Viruses
Hepatitis E
Astroviruses
Coxsackie/Echo viruses
Adenovirus 40/41
Norwalk virus and other caliciviruses
Rotavirus
Bacteria
Helicobacter pylori
Mycobacterium (MAC)
E. coli O157:H7
Aeromonas hydrophila
Pseudomonas aeruginosa
Acrobacter
Campylobacter
Algal Toxins
Anaebaena flos-aquae
Aphanizomenon flos-aque
Microcystis aeruginosa
Schizothrix calcicola
Workshop participants established a set of baseline criteria for
deciding whether an organism should appear on the CCL. These criteria
were (1) public health significance, (2) known waterborne transmission,
(3) occurrence in source water, (4) effectiveness of current water
treatment, and (5) adequacy of analytical methods. Organisms on the EPA
list mentioned above, as well as other organisms that arose during the
discussions, were evaluated against these criteria.
The CCL published today includes the list of pathogens identified
by the workshop and subsequently adopted by the NDWAC as
recommendations for the CCL. Algal toxins were considered to be of
minimal public health significance, and therefore were not included on
the draft CCL. The following sections identify the organisms selected,
the rationale for why a pathogen was included on the CCL, and the
rationale why certain pathogens were not included.
1. Protozoa
The following protozoa are included on the CCL: Cyclospora
cayetanensis, Toxoplasma gondii, the two microsporida--Enterocytozoon
and Septata, and Acanthamoeba. It is recommended that EPA develop
guidance for controlling Acanthamoeba, for individuals who wear contact
lenses. The rationale for their selection follows.
C. cayetanensis has caused waterborne outbreaks in other countries
and one documented outbreak in the U.S. Thus, it may be a significant
public health risk. Disease symptoms include watery diarrhea, abdominal
cramping, decreased appetite, and low-grade fever (Huang et al., 1995).
In HIV-infected persons, the disease may be chronic and constant (Soave
and Johnson, 1995). The occurrence of this organism in natural waters
and its animal host range are unknown. However, C. cayetanensis is
transmitted by the fecal-oral route, and so its presence in water is
likely. The morphology of C. cayetanensis suggests that the organism is
relatively resistant to disinfectants, but due to its large size (7-
10m in diameter) it may be removed satisfactorily by
filtration. Cyclospora is included on the CCL because it has caused
waterborne disease outbreaks in the U.S. and other countries.
Toxoplasma gondii causes a common infection of mammals and birds,
but the complete life cycle only occurs in wild
[[Page 52199]]
and domestic cats. The organism infects a high percentage of the human
population (50 percent in some areas of the U.S.) but, while
subclinical infections are prevalent, illness is rare (Fishback, 1992).
However, illness may be severe in fetuses and AIDS patients. Symptoms
include fever, swelling of lymph glands in the neck, blindness and
mental retardation in fetuses, and encephalitis in AIDS patients
(Fishback, 1992). There have been two documented outbreaks of
toxoplasmosis--in Panama and British Columbia--both linked
epidemiologically to drinking water. Chlorination of unfiltered surface
waters is not effective against Toxoplasma (Benenson et al., 1982).
However, due to their large size (11x12m), filtration may be
effective in controlling this organism. Toxoplasma is included on the
CCL because it poses a significant public health risk, can be
transmitted via the waterborne route, and because a reasonable
potential exists for completing the needed research in the next few
years for controlling this organism.
Microsporidia are a large group of protozoan parasites that are
common in the environment and multiply only inside cells (Cali, 1991).
Five species of microsporidia have been reported to cause disease in
humans, but only two are significant in water: Enterocytozoon bieneusi
and Septata intestinalis. Both are common in people with AIDS
(Goodgame, 1996) and occur chiefly in AIDS patients (Bryan, 1995),
although infections have been reported in otherwise healthy persons
(Weber et al., 1994). Symptoms may include diarrhea (sometimes severe
and chronic), and illness involving the respiratory tract, urogenital
tract, eyes, kidney, liver or muscles (Bryan, 1995; Goodgame, 1996;
Cali, 1991).
Microsporidia that infect humans produce small (1-5m),
very resistant spores (Waller, 1979; Cali, 1991). They are shed in
bodily fluids, including urine and feces, and thus have a strong
potential to enter water sources. However, no waterborne outbreak has
yet been reported and there is no published evidence of waterborne
transmission. Chlorine is probably not effective against microsporidia,
given that other protozoan spores (cysts, oocysts) are resistant to
chlorine. Thus, effective filtration and watershed control may be
needed to control this organism in drinking water. E. bieneusi and S.
intestinalis are included on the CCL because they pose a significant
risk to immuno-compromised individuals and may not be removed
effectively by filtration because of their small size (the spores are
somewhat smaller than Cryptosporidium oocysts).
Acanthamoeba are a group of free-living amoeba that are common in
soil and water, including drinking water (Sawyer, 1989; Gonzalez de la
Cuesta et al., 1987). Some Acanthamoeba species are pathogenic and can
cause inflammation of the eye's cornea (especially in individuals who
wear soft or disposable contact lenses (Seal et al., 1992)), and
chronic encephalitis in the immuno-compromised population (Kilvington,
1990). To date, no case of waterborne disease has been reported.
However, Acanthamoeba cysts are relatively resistant to chlorine (De
Jonkheere and Van der Voorde, 1976). Because drinking water is not a
suspected route of transmission, workshop members did not include
Acanthamoeba on their list. However, as stated above, the Workshop
participants and the NDWAC recommend that EPA issue guidance to educate
the public about the potential problem with contact lenses.
Two protozoa that were on the initial list for consideration
developed by EPA (Naegleria fowleri, Isospara belli), and two that were
not (Entamoeba histolytica, Blastocystis hominis) were also considered
by the workshop, but were not included on the CCL. The reasons for
excluding them follow.
N. fowleri is a free-living amoeba, about 8-15m in size,
found in soil, water, and decaying vegetation. Although it is common in
many surface waters, it rarely causes disease. All disease incidents
have been associated with swimming in natural or manmade, warm fresh
waters; drinking water is not a suspected route of transmission. The
route of infection is via inhalation rather than by ingestion. For this
reason, it was not included on the CCL.
I. belli causes gastrointestinal illness, primarily in AIDS
patients and children. There have been no documented cases of
waterborne transmission. However, the organism is transmitted by
the fecal-oral route, so its presence in water is possible.
Filtration is probably effective in removing I. belli oocysts,
given their large size (30x12m). This organism was not
included on the CCL because of the lack of documentation on
waterborne transmission and the belief that not enough is known
about the organism for developing potential regulations within a
three-year time-frame.
E. histolytica is not considered to be a significant health problem
in the U.S. In contrast to the situation for Giardia and
Cryptosporidium, animals are not host reservoirs for E. histolytica.
Thus, the potential for source water contamination is relatively low,
especially if sewage treatment practices are adequate. Moreover, the
organism has not caused a significant waterborne disease outbreak since
the early 1950s. Thirdly, the cyst is large (10-15m), slightly
larger than a Giardia cyst; thus, filtration should be effective for
removing this organism. For these reasons, this organism was not
included on the CCL.
B. hominis was not included on the CCL because its clinical
significance has not been determined and very little is known about its
potential for waterborne transmission or its occurrence in water.
2. Viruses
The following viruses are included on the CCL: caliciviruses,
adenoviruses, coxsackieviruses, echoviruses, and the hepatitis A virus.
The rationale for their inclusion follows.
The caliciviruses are a common cause of acute, but mild,
gastrointestinal illness in the U.S. Between 1980 and 1994, 14
waterborne disease outbreaks with more than 9,000 associated cases
caused by the Norwalk virus and other caliciviruses were reported.
Thus, their public health significance is high. However, because
adequate recovery and assay methods for the caliciviruses are not yet
available, information about the occurrence of these viruses in water
or the effectiveness of water treatment is lacking. It is believed that
current research programs might fill the research gap in the near-term
to allow development of regulations, if necessary, to control this
group of organisms.
Most of the adenoviruses are respiratory pathogens. However,
serotypes 40 and 41 are important causes of gastrointestinal illness,
especially in children. However, all types may be shed in the feces,
and may be spread by the fecal-oral route. Although adenoviruses have
been detected in water, data on their occurrence in water are meager.
No drinking water outbreaks implicating these viruses have been
reported. Both the respiratory and gastrointestinal adenoviruses are
recommended for the CCL because of their high public health
significance and data which suggest that adenoviruses are relatively
resistant to disinfectants.
The coxsackieviruses are readily found in wastewater and surface
water, and sometimes in drinking water (Hurst, 1991). Although they
have not caused a documented outbreak of waterborne disease,
coxsackieviruses produce a variety of illnesses in humans, including
the common cold, heart
[[Page 52200]]
disease, fever, aseptic meningitis, gastrointestinal problems, and many
more, some of which can be serious (Melnick, 1992). Coxsackieviruses
are included on the CCL because they are found more frequently in water
than other viruses and are associated with a number of illnesses.
The echoviruses, like the coxsackieviruses, are readily detected in
water, including treated drinking water. They are associated with
milder illnesses than the coxsackieviruses, and have not caused a
documented outbreak. Echoviruses are included on the CCL because, like
the coxsackieviruses, they are found more frequently in water than
other viruses and are associated with a number of illnesses.
The hepatitis A virus has caused at least 11 waterborne disease
outbreaks of infectious hepatitis since 1980. Therefore, it has a high
public health significance. The virus has been found in contaminated
drinking water, and is somewhat resistant to chlorination (Peterson et
al., 1983). For these reasons, it is also included on the CCL.
Three viruses that were on the initial list for consideration
developed by EPA (rotaviruses, hepatitis E virus, and astroviruses) and
two that were not (picobivirna and picotrivirna) were also considered
by the workshop participants, but were not included on the CCL. The
reasons for not including them follow.
Rotaviruses cause acute gastroenteritis, primarily in children.
Almost all children have been infected at least once by the age of five
years (Parsonnet, 1992), and in developing countries, rotavirus
infections are a major cause of infant mortality. Rotaviruses are
spread by fecal-oral transmission and have been found in ambient water,
ground water, and tap water (Gerba et al., 1985; Gerba, 1996). However,
only a single waterborne disease outbreak has been reported in the U.S.
and only several have been documented outside the U.S. (Gerba et al.,
1985). Rotaviruses are readily inactivated by chlorine, chlorine
dioxide, and ozone, but apparently not by monochloramine (Berman and
Hoff, 1984; Chen and Vaughn, 1990, Vaughn et al., 1986; 1987).
Rotaviruses were not included on the CCL because they are not regarded
as an important public health problem in the U.S., and because of their
vulnerability to disinfectants.
Hepatitis E virus is an important agent of hepatitis in
underdeveloped countries, but apparently not in the U.S. The virus is
transmitted by the fecal-oral route (Dreesman and Reyes, 1992) and
probably a majority of cases are waterborne. Even though the disease is
apparently not a health concern in the U.S., one investigation found
that 21.3% of blood donors in Baltimore were sero-positive (Thomas et
al., 1997), suggesting previous exposure to the organism. Infections
are mild and self-limiting except for pregnant women, who have a
fatality rate of up to 39%. No data from disinfection studies have been
published. Hepatitis E virus was not included on the CCL because it is
not regarded as a significant public health threat in the U.S., and
because current sewage treatment practices are judged sufficient to
eliminate risk of waterborne transmission.
Astroviruses are found throughout the world and cause illness in 1-
3 year old children and in AIDS patients, but rarely in healthy adults
(Kurtz and Lee, 1987; Grohmann et al., 1993). Symptoms are mild and
typical of gastrointestinal illness, but the disease is more severe and
persistent in the severely immuno-compromised. Astroviruses are
transmitted by the fecal-oral route and have been detected in water and
have been associated anecdotally with waterborne disease outbreaks
(Cubitt, 1991; Pinto et al., 1996). The astroviruses were not included
on the CCL because of the mildness of the illness and the lack of
adequate documentation about the occurrence in water and potential as a
waterborne disease agent.
The picobivirna and picotrivirna viruses are of public health
significance outside the U.S., and are not regarded as being a
waterborne problem in the U.S. and are adequately removed from effluent
water by current sewage treatment practices. Picobivirna and
picotrivirna viruses were not included on the CCL for these reasons.
3. Bacteria
The following bacteria are included on the CCL: Helicobacter
pylori, Legionella, Mycobacterium avium complex, and Aeromonas
hydrophila. The rationale for their identification follows.
H. pylori has been closely associated with peptic ulcers, gastric
carcinoma, and gastritis (Peterson, 1991; Nomura et al., 1991;
Parsonnet et al., 1991, Cover and Blaser, 1995). Data about its
distribution in the environment are scarce, but the organism has been
found in sewage (Sutton et al., 1995) and has been linked to ambient
water and drinking water by epidemiological tests and other means
(Klein et al., 1991; Shahamat et al., 1992; Shahamat et al., 1993;
Hulten et al., 1996). The number of people in the U.S. that have
antibodies against H. pylori, and thus have been exposed to the
organism, is high. Helicobacter is thought to be vulnerable to
disinfectants. H. pylori is included on the CCL because of its public
health significance in the U.S. and the possibility of waterborne
transmission.
Legionella pneumophila and other Legionella species cause
Legionnaires Disease (a type of pneumonia) and Pontiac Fever (a mild,
nonpneumonic illness). Legionnaires Disease, which has a 15% mortality
rate, typically results from the inhalation of aerosols of water
containing the organism. Legionella are abundant and naturally
occurring in surface water; thus they are not necessarily associated
with fecal contamination. They have also been detected in ground water.
Small numbers can occur in the finished waters of systems employing
full treatment (U.S. EPA, 1989b) and can colonize plumbing systems,
especially warm ones. Aerosols from fixtures, such as showerheads, may
cause the disease via inhalation. Aerosols from cooling towers, hot
tubs, and pools have also caused a number of outbreaks. Direct person-
to-person spread has not been documented (Yu et al., 1983). Ozone,
chlorine dioxide, and ultraviolet light are effective in controlling
Legionella, but data for chlorine are inconsistent (States et al.,
1990). Legionella in surface water are already regulated under EPA's
Surface Water Treatment Regulations (40 CFR part 141, subpart H).
Legionella in ground water is included on the CCL because of their
public health significance in the U.S. and the possibility of
waterborne transmission via ground water.
Mycobacterium avium complex (MAC; also known as the Mycobacterium
avium intracellulare complex) is common in the environment and can
colonize water systems and plumbing systems (du Moulin and Stottmeier,
1986; du Moulin et al., 1988). It is known to cause pulmonary disease
and other diseases, especially in individuals with a weakened immune
system (e.g., AIDS patients). Drinking water has been epidemiologically
linked to infections in hospital patients (du Moulin and Stottmeier,
1986). MAC is relatively resistant to chlorine disinfection (Pelletier
et al., 1988). MAC is included on the CCL because of its high public
health significance, its ability to colonize on pipes, and its relative
resistance to chlorine.
Aeromonas hydrophila can cause wound infections and septicemia in
people with a weakened immune system, and some evidence suggests that
it causes gastrointestinal disease in
[[Page 52201]]
healthy people. The organism is common in water and is not necessarily
associated with fecal contamination. It is vulnerable to disinfectants.
A. hydrophila is included on the CCL primarily because it is common in
source water.
Pseudomonas aeruginosa is a free-living bacterium that is common in
water. People at risk include patients with profound neutropenia,
cystic fibrosis, severe burns, and those with foreign devices installed
(Hardalo and Edberg, 1997). The organism has also caused numerous
outbreaks of dermatitis in recreational waters, e.g., pools,
whirlpools, and hot tubs (Kramer et al., 1996). Because of differing
opinions among the microbiologists who participated in the workshop
about its public health significance and its potential health risk via
the waterborne route, a decision could not reach on whether to include
P. aeruginosa on their list. Rather, it was recommended that EPA
conduct a complete literature search on the topic before the Agency
decides whether to include this organism on the final list. The
literature search will be conducted prior to publishing the final CCL.
Four bacteria that were on the initial list for consideration
developed by EPA (Escherichia coli O157:H7, Campylobacter, Arcobacter,
and the cyanobacteria) and four that were not (Salmonella, Shigella,
Vibrio cholerae and other Vibrio species, and Yersinia enterocolitica)
were also considered by the workshop, but were not included on the CCL.
The reasons for excluding them follow.
E. coli O157:H7, Campylobacter, Salmonella, Shigella, V. cholerae,
and Y. enterocolitica have all caused waterborne disease in the U.S.
and are regarded as significant health risks. They were not included on
the CCL because current treatment practices were deemed to be adequate
in controlling these organisms. Arcobacter was not included on the CCL
because its health significance and the possibility of waterborne
transmission are unknown, and because current treatment practices were
judged likely in controlling this organism.
Cyanobacteria (also known as blue-green algae) are generally not
considered an important health risk. However, certain species may
produce neurotoxins (which affects the nervous system), hepatotoxins
(which affects the liver), and other types of toxins which, if ingested
at high enough concentrations, may be harmful. High concentrations of
toxins associated with a bloom of Schizothrix calcicola may have been
responsible for an outbreak of gastroenteritis in 1975 (Lippy and Erb,
1976). However, little evidence exists that ambient levels found in
most water supplies pose a health risk to the normal population. The
cyanobacteria was not included on the CCL because the problem is
thought to be best handled through good watershed management practices
to prevent algal growth in source waters.
4. Microbiological Indicators
Indicators of fecal contamination or of pathogens were not
addressed at the workshop. EPA is involved, however, in a project with
the International Life Sciences Institute to begin an evaluation of
which microbiological indicators are most appropriate for various types
of environmental waters. Currently, the Agency uses total coliform
bacteria as the sole indicator of microbiological drinking water
quality.
5. Future Activities Planned for Microbiological Contaminants and the
CCL
EPA is attempting to develop a more formal framework for
identifying, selecting and prioritizing pathogens (and their
indicators) for research and possible regulation, and for future CCLs.
To date, the identification of pathogens for the CCL has been
relatively informal. In contrast, a more objective approach for
contaminant identification and selection in the future may be based on
a numerical scoring procedure such that contaminants with higher scores
would have greater priority for regulation, research and guidance
development than those that have lower scores.
6. Possible Impacts From Other Regulatory Activity
Pathogens that are included on the final CCL, will be candidates
for regulatory control, guidance development, and additional research
over the next five years. These organisms may be controlled, however,
by regulations currently under development such as the Enhanced Surface
Water Treatment Rule, the Ground Water Disinfection Rule. If pathogens
on the CCL are determined to be controlled by these regulations, they
will be withdrawn from the CCL.
C. Chemical Contaminants Identified for the Draft CCL
As stated earlier, the NDWAC Working Group on Occurrence &
Contaminant Selection played an integral part in developing the draft
CCL presented in today's notice. At the initial Working Group meeting
held on April 3-4, 1997, the Agency proposed a number of lists of
contaminants as a logical starting point for developing the draft CCL.
Some lists originate from other Agency programs, while others were
developed in anticipation of future DWPLs. The Agency also proposed
that the initial list would need to be reduced to a smaller list of
priority contaminants that would become the CCL.
In April, the Working Group identified 32 contaminants thought to
be those most important for inclusion on the first CCL, other
contaminants for initial consideration, and criteria to be used to
evaluate and screen all contaminants initially considered. During this
April meeting, and two subsequent meetings, held on June 23 and July
17, 1997, the Working Group developed these recommendations which were
approved by the full NDWAC, and subsequently adopted by the Agency, to
use in screening the initial list to the contaminants to today's draft
CCL. Summaries of the meetings are provided in the docket. The
following sections provide the rationale for the initial list of
contaminants considered and a summary of the development and
application of the criteria used to evaluate the contaminants on the
initial list to develop the draft CCL.
1. The Initial List of Chemical Contaminants Considered
Ten lists of chemical contaminants were considered to be logical
starting points for developing the first CCL. Of the ten, eight lists
were ultimately combined to serve as the initial list of contaminants
to be considered for the CCL. Some contaminants appear on more than one
of the eight lists. The initial list of contaminants considered, as
well as those eliminated or deferred from consideration, are in Table
3. The following sections provide a description of each of the lists
and the rationale behind including it with, or excluding it from, the
initial list of contaminants considered.
[[Page 52202]]
Table 3.--Initial List of Chemical Contaminants Considered During Development of the Draft CCL
--------------------------------------------------------------------------------------------------------------------------------------------------------
Contaminant lists considered
----------------------------------------------------------------------------------------------
Contaminant CAS No. Health Stakeholder
1991 DWPL advisories IRIS (3) PWS (4) CERCLA (5) summary TRI list OPP ranking
(1) (2) list (6) (7) (8)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Contaminants Identified as Initial Candidates for the CCL during April 3-4, 1997 Working Group Meeting
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inorganics:
Aluminum.................................. 7429-90-5 ......... ......... ........... ...........
Zinc...................................... 7440-66-6 ......... ......... ........... ........... ...........
Pesticides:
Acetochlor................................ 34256-82-1 ......... ......... ......... ........... .........
Alachlor ESA.............................. ........... ......... .......... ......... ......... ........... .........
Butylate.................................. 2008-41-5 ......... ......... ........... ........... .........
Chlorpyrifos.............................. 2921-88-2 ......... ......... ........... ......... ...........
DCPA (Dacthal)............................ 1861-32-1 ......... ......... ........... ......... ...........
DCPA di-acid degradate.................... 2136-79-0 .......... ......... ......... ........... ........... .........
DCPA mono-acid degradate.................. 887-54-7 .......... ......... ......... ........... ........... ......... ...........
DDE....................................... 72-55-9 ......... .......... ......... ........... ......... ...........
Diazinon.................................. 333-41-5 ......... ......... ......... ........... ........... .........
Diuron.................................... 330-54-1 ......... ......... ......... ........... .........
Endosulfan................................ 115-29-7 ......... .......... ......... ........... .........
EPTC (s-ethyl-dipropylthio-carbamate)..... 759-94-4 ......... .......... ......... ........... ........... .........
Malathion................................. 121-75-5 ......... D ......... ........... ........... ......... ...........
Methyl parathion.......................... 298-00-0 ......... ......... ........... ........... ......... ...........
Metolachlor............................... 51218-45-2 ......... ........... .........
Metribuzin................................ 21087-64-9 ......... ........... .........
Prometon.................................. 1610-18-0 ......... ......... ........... ........... .........
Propanil.................................. 709-98-8 ......... .......... ......... ........... ........... ......... ...........
Tebuthiuron............................... 34014-18-1 ......... ......... ......... ........... ........... ......... ...........
Terbacil.................................. 5902-51-2 ......... ......... ......... ........... ........... .........
Triazines (total) (9)..................... ........... ......... .......... ......... ......... ........... ......... ...........
Triazine degradation products (9),
atrazine-desethyl........................ 6190-65-4 ......... .......... ......... ......... ........... .........
Triazines (unregulated) (9)............... ........... ......... .......... ......... ......... ........... ......... ...........
Trifluralin.............................. 1582-09-8 ......... ........... ........... .........
Organics:
2-methyl-Phenol (o-cresol)................ 95-48-7 ......... .......... ......... ........... ........... ......... ...........
Acetone................................... 67-64-1 ......... .......... ......... ........... ........... ......... ...........
Ethylene glycol........................... 107-21-1 ......... ......... ........... ........... ...........
Methyl ethyl ketone (MEK)................. 78-93-3 ......... ......... ........... ...........
Methyl-t-butyl ether (MTBE).............. 1634-04-4 ......... ......... ........... ...........
Nitrobenzene.............................. 98-95-3 .......... ......... ........... ........... ......... ...........
Phenol.................................... 108-95-2 ......... ......... ........... ........... ...........
--------------------------------------------------------------------------------------------------------------------------------------------------------
Additional Contaminants Considered for the CCL
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inorganics:
Ammonia................................... 7664-41-7 ......... ......... ......... ........... ...........
Ammonium nitrate.......................... 6484-52-2 ......... .......... ......... ......... ........... ........... ...........
Ammonium sulfamate........................ 7773-06-0 ......... ......... ......... ........... ........... ......... ...........
Ammonium sulfate.......................... 7783-20-2 ......... ......... ......... ........... ........... ...........
Boron..................................... 7440-42-8 ......... ......... ........... ........... ......... ...........
Carbon disulfide.......................... 75-15-0 ......... .......... ......... ......... ........... ........... ...........
Carbonyl sulfide.......................... 463-58-1 ......... .......... ......... ......... ........... ........... ...........
Cobalt.................................... 7440-48-4 ......... .......... ......... ......... ........... ........... ...........
Hydrochloric acid......................... 7647-01-0 ......... .......... ......... ......... ........... ........... ...........
Hydrogen fluoride......................... 7664-39-3 ......... .......... ......... ......... ........... ........... ...........
Manganese................................. 7439-96-5 .......... ......... ......... ...........
Metam-sodium.............................. 137-42-8 ......... .......... ......... ........... ........... ......... ...........
Molybdenum................................ 7439-98-7 ......... ......... ........... ........... ......... ...........
Phosphoric acid........................... 7664-38-2 ......... .......... ......... ......... ........... ........... ...........
Phosphorous............................... 7723-14-0 ......... ......... ......... ........... ...........
Sodium.................................... 7440-23-5 ......... ......... ......... ........... ........... ......... ...........
Strontium................................. 7440-24-6 ......... ......... ........... ........... ......... ...........
Vanadium.................................. 7440-62-2 ......... ......... ........... ........... ......... ...........
Pesticides:
1,3-Dichloropropene (telone or 1,3-D)..... 542-75-6 ......... ........... .........
2,4,5-T................................... 93-76-5 ......... ......... ........... ........... ......... ...........
2,4-DB.................................... 94-82-6 ......... .......... ......... ......... ........... ........... .........
2,4-DP.................................... 120-36-5 ......... .......... ......... ......... ........... ......... ...........
[[Page 52203]]
4-Nitrophenol (p-Nitrophenol)............. 100-02-7 ......... ......... ........... ........... ......... ...........
Acephate.................................. 30560-19-1 ......... ......... ......... ........... ......... ...........
Acifluofen................................ 50594-66-6 ......... ......... ........... .........
Aldrin.................................... 309-00-2 ......... ......... ......... ........... .........
Ametryn................................... 834-12-8 ......... ......... ......... ........... .........
Amitraz................................... 33089-61-1 ......... .......... ......... ......... ........... ......... ...........
Asulam.................................... 3337-71-1 .......... ......... ......... ........... ........... .........
Bensulfuron methyl........................ ........... ......... .......... ......... ......... ........... ........... .........
Bentazon.................................. 25057-89-0 ......... ......... ........... ........... .........
Benzidine................................. 92-87-5 ......... .......... ......... ......... ........... ......... ...........
Bromacil.................................. 314-40-9 ......... ......... ........... .........
Bromoxynil................................ 1689-84-5 ......... .......... ......... ........... ........... .........
Cadre..................................... ........... ......... .......... ......... ......... ........... ........... .........
Caprolactum............................... 105-60-2 ......... .......... ......... ........... ........... ......... ...........
Captan.................................... 133-06-2 ......... .......... ......... ........... ........... ......... ...........
Carbaryl.................................. 63-25-2 ......... ......... ........... ........... ......... ...........
Carboxin.................................. 5234-68-4 ......... ......... ......... ........... ........... ......... ...........
Chloramben................................ 133-90-4 ......... ......... ......... ........... ......... ...........
Chlorimuron ethyl......................... 90982-32-4 ......... .......... ......... ......... ........... ........... .........
Chlorothalonil............................ 1897-45-6 ......... ......... ........... ........... ......... ...........
Chlorsulfuron............................. 64902-72-3 ......... .......... ......... ......... ........... ........... .........
Clopyralid................................ 1702-17-6 ......... .......... ......... ......... ........... ......... ...........
Cyanazine................................. 21725-46-2 ......... ........... .........
Cyromazine................................ 66215-27-8 .......... ......... ......... ........... ......... ...........
DDD....................................... 72-54-8 ......... .......... ......... ......... ........... ......... ...........
DDT....................................... 50-29-3 ......... .......... ......... ........... ......... ...........
Diazinon--oxypyrimidine................... ........... ......... .......... ......... ......... ........... ........... .........
Dicamba................................... 1918-00-9 ......... ......... ........... .........
Dichlobenil............................... 1194-65-6 ......... .......... ......... ......... ........... ......... ...........
Dieldrin.................................. 60-57-1 ......... ......... ......... ......... ...........
Dimethoate................................ 60-51-5 ......... .......... ......... ........... ......... ...........
Dimethrin................................. 70-38-2 ......... ......... ......... ........... ........... ......... ...........
Diphenamid................................ 957-51-7 ......... ......... ......... ........... ........... ......... ...........
Disulfoton................................ 298-04-4 ......... ......... ......... ........... ......... ...........
Endosulfan sulfate........................ 1031-07-8 ......... .......... ......... ......... ........... ......... ...........
Ethalfluralin............................. 55283-68-6 ......... .......... ......... ......... ........... ........... .........
Ethofumesate.............................. 26225-79-6 ......... .......... ......... ......... ........... ......... ...........
Ethoprop.................................. 13194-48-4 ......... .......... ......... ......... ........... ......... ...........
Ethylenethiourea (ETU).................... 96-45-7 ......... ......... ........... ........... .........
Fenamiphos................................ 22224-92-6 ......... ......... ......... ........... .........
Fluazifop-p-butyl......................... ........... ......... .......... ......... ......... ........... ........... .........
Fluometuron............................... 2164-17-2 ......... ......... ......... ........... ........... .........
Fomesafen................................. 72178-02-0 .......... ......... ......... ........... ........... ......... ...........
Fonofos................................... 944-22-9 ......... ......... ........... ......... ...........
Halofenozide.............................. ........... ......... .......... ......... ......... ........... ........... .........
Halosulfuron.............................. ........... ......... .......... ......... ......... ........... ........... .........
Hexazinone................................ 51235-04-2 ......... .......... ......... ......... ........... .........
Imazamethabenz............................ 81405-85-8 ......... .......... ......... ......... ........... ........... .........
Imazapyr.................................. ........... ......... .......... ......... ......... ........... ........... .........
Imazaquin................................. 81335-37-7 ......... .......... ......... ......... ........... ........... .........
Imazethapyr............................... 81335-77-5 ......... .......... ......... ......... ........... .........
Imidacloprid.............................. ........... ......... .......... ......... ......... ........... ......... ...........
Lactofen.................................. 77501-63-4 .......... ......... ......... ........... ........... ......... ...........
Linuron................................... 330-55-2 ......... .......... ......... ........... ........... ......... ...........
Maneb (ETU precursor)..................... 12427-38-2 ......... .......... ......... ........... ........... ......... ...........
MCPA...................................... 94-74-6 ......... ......... ......... ........... ......... ...........
MCPP...................................... 93-65-2 ......... .......... ......... ......... ........... ......... ...........
Metalaxyl................................. 57837-19-1 .......... ......... ......... ........... ........... ......... ...........
Methazole................................. 20354-26-1 ......... .......... ......... ......... ........... ........... .........
Methomyl.................................. 16752-77-5 .......... ......... ........... ......... ...........
Metsulfuron methyl........................ 74223-64-6 ......... .......... ......... ......... ........... .........
Molinate.................................. 2212-67-1 ......... .......... ......... ........... ........... ......... ...........
MSMA...................................... 2163-80-6 ......... .......... ......... ......... ........... ........... .........
Napropamide............................... 15299-99-7 ......... .......... ......... ......... ........... ......... ...........
Nicosulfuron.............................. ........... ......... .......... ......... ......... ........... ........... .........
Norflurazon............................... 27314-13-2 ......... .......... ......... ......... ........... .........
[[Page 52204]]
Paraquat.................................. 4685-14-7 ......... ......... ........... ........... .........
Pendimethalin............................. 40487-42-1 ......... .......... ......... ........... ........... .........
Primisulfuron methyl...................... ........... ......... .......... ......... ......... ........... ........... .........
Prometryn................................. 7287-19-6 ......... .......... ......... ......... ........... ........... .........
Pronamide................................. 23950-58-5 .........