E5-6971. Notice of the Revised Priority List of Hazardous Substances That Will Be the Subject of Toxicological Profiles

AGENCY:

Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services (HHS).

ACTION:

Notice.

SUMMARY:

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund), as amended by the Superfund Amendments and Reauthorization Act (SARA), requires that ATSDR and the Environmental Protection Agency (EPA) revise the Priority List of Hazardous Substances. This list includes substances most commonly found at facilities on the CERCLA National Priorities List (NPL) which have been determined to be of greatest concern to public health at or around these NPL hazardous waste sites. This announcement provides notice that the agencies have developed and are making available a revised CERCLA Priority List of 275 Hazardous Substances, based on the most recent information available. Each substance on the priority list is a candidate to become the subject of a toxicological profile prepared by ATSDR and subsequently a candidate for the identification of priority data needs.

In addition to the Priority List of Hazardous Substances, ATSDR has developed a Completed Exposure Pathway Site Count Report. This report lists the number of sites or events with ATSDR activities where a substance has been found in a completed exposure pathway (CEP). This report is included in the Support Document of the Priority List.

ADDRESSES:

Requests for a printed copy of the report, the 2005 CERCLA Priority List of Hazardous Substances That Will Be The Subject of Toxicological Profiles and Support Document, including the CEP report, should bear the docket control number ATSDR-217, and should be submitted to: Ms. Olga Dawkins, Division of Toxicology and Environmental Medicine, Mail Stop F-32, 1600 Clifton Road, NE., Atlanta, GA 30333. Requests must be in writing.

Electronic Availability: The 2005 Priority List of Hazardous Substances and Support Document will be posted on ATSDR's Web site located at http://www.atsdr.cdc.gov/​clist.html. The CEP Report will also be posted at http://www.atsdr.cdc.gov/​cep.html.

This is an informational notice only, and comments are not being solicited at this time. However, any comments received will be considered for inclusion in the next revision of the list and placed in a publicly accessible docket; therefore, please do not submit confidential business or other confidential information.

FOR FURTHER INFORMATION CONTACT:

ATSDR, Division of Toxicology and Environmental Medicine, 1600 Clifton Road, NE., Mail Stop F-32, Atlanta, GA 30333, telephone [phone].

SUPPLEMENTARY INFORMATION:

CERCLA establishes certain requirements for ATSDR and EPA with regard to hazardous substances that are most commonly found at facilities on the CERCLA NPL. Section 104(i)(2) of CERCLA, as amended [42 U.S.C. 9604(i)(2)], required that the two agencies prepare a list, in order of priority, of at least 100 hazardous substances that are most commonly found at facilities on the NPL and which, in their sole discretion, have been determined to pose the most significant potential threat to human health (see 52 FR 12866, April 17, 1987). CERCLA also required the agencies to revise the priority list to include 100 or more additional hazardous substances (see 53 FR 41280, October 20, 1988), and to include at least 25 additional hazardous substances in each of the three successive years following the 1988 revision (see 54 FR 43619, October 26, 1989; 55 FR 42067, October 17, 1990; 56 FR 52166, October 17, 1991). CERCLA also requires that ATSDR and EPA shall, at least annually thereafter, revise the list to include additional hazardous substances that have been determined to pose the most significant potential threat to human health. In 1995, the agencies altered the publication schedule of the priority list by moving to a 2-year publication schedule, reflecting the stability of this listing activity (60 FR 16478, March 30, 1995). As a result, the priority list is now on a 2-year publication schedule with a yearly informal review and revision. Each substance on the CERCLA Priority List of Hazardous Substances is a candidate to become the subject of a toxicological profile prepared by ATSDR and subsequently a candidate for the identification of priority data needs.

The initial priority lists of hazardous substances (1987-1990) were based on the most comprehensive and relevant information available when the lists were developed. More comprehensive sources of information on the frequency of occurrence and the potential for human exposure to substances at NPL sites became available for use in the 1991 priority list with the development of ATSDR's HazDat database. Utilizing this database, a revised approach and algorithm for ranking substances was developed in 1991, and a notice announcing the intention of ATSDR and EPA to revise and rerank the Priority List of Hazardous Substances was published on June 27, 1991 (56 FR 29485). The subsequent 1991 Priority List and revised approach used for its compilation was summarized in the “Revised Priority List of Hazardous Substances” Federal Register notice published October 17, 1991 (56 FR 52166). The same approach and the same basic algorithm have been used in all subsequent activities, including the 2005 listing activity. The algorithm used in ranking hazardous substances on the priority list consists of three criteria, which are combined to result in the total score. The three criteria are: Frequency of occurrence at NPL sites; toxicity; and potential for human exposure.

Since HazDat is a dynamic database with ongoing data collection, additional information from the HazDat database became available for the 2005 listing activity. This additional information has been entered into HazDat since the development of the 2003 Priority List of Hazardous Substances. The site-specific information from HazDat that is used in the listing activity has been collected from ATSDR public health assessments and from site file data packages that are used to develop these public health assessments. The new information may include more recent NPL frequency of occurrence data, additional concentration data, and more information on exposure to substances at NPL sites. With these additional data, 10 substances have been replaced on the list of 275 substances since the 2003 publication. Of the 10 replacement substances, 2 are new candidate substances, and 8 are substances that were previously under consideration. These replacement substances and changes in the order of substances appearing on the CERCLA Priority List of Hazardous Substances will be reflected in the program activities that rely on the list for future direction.

The 2005 Priority List of Hazardous Substances includes 275 substances that have been determined to be of greatest concern to public health based on the criteria of CERCLA section 104(i)(2) [42 U.S.C. 9604(i)(2)]. A total of 861 candidate substances have been analyzed and ranked with the current algorithm. Of these candidates, the 275 substances on the priority list may become the subject of toxicological profiles in the future. The top 25 substances on the 2005 Priority List of Hazardous Substances are listed below.

Rank	Substance name
1	Arsenic
2	Lead
3	Mercury
4	Vinyl Chloride
5	Polychlorinated Biphenyls
6	Benzene
7	Polycyclic Aromatic Hydrocarbons
8	Cadmium
9	Benzo (A) Pyrene
10	Benzo (B) Fluoranthene
11	Chloroform
12	Ddt, P,P'-
13	Aroclor 1254
14	Aroclor 1260
15	Dibenzon (A,H) Anthracene
16	Trichloroethylene
17	Dieldrin
18	Chromium, Hexavalent
19	Phosphorus, White
20	Dde, P,P'-
21	Chlordane
22	Hexachlorobutadiene
23	Coal Tar Creosote
24	Ddd, P',P'-
25	Aldrin

ATSDR intends to publish the next revised list of hazardous substances in two years, with an informal review and revision performed in one year. These revisions will reflect changes and improvements in data collection and availability. Additional information on the existing methodology used in the development of the CERCLA Priority List of Hazardous Substances can be found in the Support Document to the List and in the Federal Register notices mentioned above.

In addition to the revised priority list, ATSDR is also releasing a Completed Exposure Pathway Site Count Report. A completed exposure pathway (CEP) is an exposure pathway that links a contaminant source to a receptor population. The CEP ranking is very similar to a sub-component of the potential-for-human-exposure component of the listing algorithm. The CEP ranking is based on a site frequency count, and thus lists the number of sites at which a substance has been found in a CEP. ATSDR's HazDat database contains this information which is derived from ATSDR public health assessments and health consultations. Because exposure to hazardous substances is of significant concern, ATSDR is publishing this CEP report along with the CERCLA Priority List of Hazardous Substances. Since this CEP report focuses on documented exposure, it provides an important prioritization based on substances to which people are exposed.

The substances on the CEP report are similar to the substances on the CERCLA Priority List of Hazardous Substances. However, there are some substances that are on the CEP report because they are frequently found in completed exposure pathways, but are not on the CERCLA Priority List because they have a very low toxicity (e.g., sodium). Since the CERCLA Priority List incorporates three different components (toxicity, frequency of occurrence, and potential for human exposure) to determine its priority substances, substances with very low toxicity are not on the CERCLA Priority List and consequently are not the subject of toxicological profiles. In addition, since the Priority List is mandated by CERCLA, it only uses data from sites on the CERCLA National Priorities List, whereas the CEP report uses data from all sites with ATSDR activities that have a CEP. Of the 100 substances on the CEP report, the 25 substances found at the most number of sites in a CEP are presented below.

Substance name	Number of sites with substance in a CEP
	All sites	NPL sites
Lead	431	267
Trichloroethylene	363	286
Arsenic	341	208
Tetrachloroethylene	280	207
Benzene	210	137
Cadmium	207	136
Volatile Organic Compounds, Unspecified	193	132
Chromium	193	129
Polychlorinated Biphenyls	177	116
Mercury	167	93
Manganese	164	95
Zinc	158	95
Copper	143	83
1,1,1-Trichloroethane	135	110
Chloroform	124	92
Benzo(A)Pyrene	122	58
1,1-Dichloroethene	117	96
Polycyclic Aromatic Hydrocarbons	117	79
Nickel	112	70
Methylene Chloride	111	73
Toluene	111	68
Antimony	108	69
Vinyl Chloride	103	84
Barium	102	56
1,2-Dichloroethane	96	77
Note: Sorted by the All Sites column.
All Sites = all sites with ATSDR activities that have a CEP; NPL.
Sites = current and former sites on the National Priorities List, as mandated.

Dated: November 29, 2005.

Ken Rose,

Acting Director, Office of Policy, Planning and Evaluation, National Center for Environmental Health/Agency for Toxic Substances and Disease Registry.