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 of 1980 (CERCLA or Superfund), as amended by the Superfund Amendments and Reauthorization Act of 1986 (SARA), requires that ATSDR and the Environmental Protection Agency(EPA) prepare a Priority List of Hazardous Substances commonly found at facilities on the CERCLA National Priority List (NPL). The Priority List of Hazardous Substances includes substances that have been determined to be of greatest public health concern to persons at or near NPL sites. CERCLA as amended also requires that ATSDR and EPA periodically revise the Priority List of Hazardous Substances.

Pursuant to these CERCLA mandates, the agencies announce that based on the most recent information available, they have developed and now make available a revised CERCLA Priority List of 275 Hazardous Substances. Because CERCLA as amended also requires ATSDR to prepare and to periodically revise toxicological profiles on hazardous substances included in the priority list, each priority list substance is a potential toxicological profile subject, as well as a candidate for 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 at which ATSDR is involved and wherein 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 2007 CERCLA Priority List of Hazardous Substances That Will Be The Subject of Toxicological Profiles and Support Document, including the CEP report, should include the docket control number ATSDR-238, and should be submitted to Ms. Nickolette Roney, Division of Toxicology and Environmental Medicine, ATSDR, Mail Stop F-32, 1600 Clifton Road, NE., Atlanta, GA 30333. Requests must be in writing.

Electronic Availability: The 2007 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; no comments are solicited at this time. Any comments received will, however, be considered for inclusion in the next revision of the list and placed in a publicly accessible docket. Therefore, please do not include in comments any confidential business information or any other confidential information.

FOR FURTHER INFORMATION CONTACT:

Division of Toxicology and Environmental Medicine, ATSDR, 1600 Clifton Road NE., Mail Stop F-32, Atlanta, GA 30333, telephone 800-232-4636.

SUPPLEMENTARY INFORMATION:

CERCLA establishes certain requirements for ATSDR and EPA with regard to hazardous substances most commonly found at facilities on the CERCLA NPL. Section 104(i)(2)(A) of CERCLA, as amended, requires that ATSDR and EPA prepare a list, in order of priority, of at least 100 hazardous substances most commonly found at facilities on the NPL and which, in the agencies' sole discretion, pose the most significant potential threats to human health (see also 52 FR 12866, April 17, 1987). CERCLA section 104 (i)(2)(B) also requires the agencies to revise the priority list to include 100 or more additional hazardous substances (see also 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; and 56 FR 52166, October 17, 1991).CERCLA section 104(i)(2)(B) further requires ATSDR and EPA at least annually to revise the list to include any additional hazardous substances that have been determined to pose the most significant potential threat to human health.

In 1995, the agencies, recognizing the stability of this listing activity, altered the priority list publication schedule (60 FR 16478, March 30, 1995). As a result, the priority list is now on a 2-year schedule, with annual informal review and revision. Each substance on the CERCLA Priority List of Hazardous Substances is also a potential subject of an ATSDR-prepared toxicological profile 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 then available. In 1991, with the development of ATSDR's HazDat database, more comprehensive sources of information became available on the frequency of occurrence and the potential for human exposure to substances at NPL sites. Using this updated database, in 1991 a revised approach and algorithm for ranking substances was developed. On June 27, 1991, a notice announcing the intention of ATSDR and EPA to revise and rerank the Priority List of Hazardous Substances was published (56 FR 29485). The 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 listing activities, including 2007. The algorithm 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.

Because HazDat is a dynamic database in which data collection is ongoing, additional information from the HazDat database became available for the 2007 listing activity. Since the development of the 2005 Priority List of Hazardous Substances, this additional information has been entered into HazDat. The site-specific information from HazDat used in the listing activity has been collected from ATSDR public health assessments and from site-file data packages used to develop the 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. Using these additional data, one substance has been replaced on the list of 275 substances since the 2005 publication; the replacement substance was previously under consideration. Changes in the order of substances appearing on the CERCLA Priority List of Hazardous Substances will be reflected in program activities that rely on the list for future direction.

The 2007 Priority List of Hazardous Substances contains, based on CERCLA § 104(i)(2)(A) criteria, 275 substances that represent the greatest concern to public health. Using the current algorithm, a total of 859 candidate substances have been analyzed and ranked. Of these candidates, the 275 substances on the priority list may in the future become subjects of toxicological profiles.

In 2 years ATSDR intends to publish the next revised list of hazardous substances, with an informal review and revision performed in 1 year. These revisions will reflect changes and improvements in data collection and in availability. Additional information on the existing methodology used in the development of the CERCLA Priority List of Hazardous Substances can be found in the List Support Document and in the above-referenced Federal Register notices.

In addition to the revised priority list, ATSDR is also releasing a Completed Exposure Pathway Site Count Report. A completed exposure pathway (CEP) links a contaminant source to a receptor population. The CEP ranking is similar to a subcomponent of the listing algorithm's potential-for-human-exposure component. 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 from health consultations. The CEP report therefore focuses on documented exposure, and lists hazardous substances according to exposure frequency. Because exposure to hazardous substances is a matter of concern, ATSDR publishes this CEP report together with the CERCLA Priority List of Hazardous Substances.

The substances in the CEP report are similar to those in the CERCLA Priority List of Hazardous Substances. Substances are listed in the CEP report because they are frequently found in completed exposure pathways. Some of these substances, however, have a very low toxicity (e.g., sodium) and as a result are not included in the CERCLA Priority List. As stated, given that the CERCLA Priority List uses toxicity, frequency of occurrence, and potential for human exposure to determine its priority substances, other low-toxicity substances will not appear on the CERCLA Priority List and, consequently, will not become subjects of toxicological profiles. In addition, because CERCLA mandates the preparation of the Priority List, that list only incorporates data from CERCLA NPL sites. The CEP report, on the other hand, uses data from all ATSDR-activity sites at which a CEP has been detected.