[Federal Register Volume 59, Number 176 (Tuesday, September 13, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22442]


[[Page Unknown]]

[Federal Register: September 13, 1994]


-----------------------------------------------------------------------

ENVIRONMENTAL PROTECTION AGENCY
[FRL-5070-7]

 

Reassessment of 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-
TCDD, dioxin)

AGENCY: Environmental Protection Agency (EPA).

ACTION: As part of the Agency's reassessment of 2,3,7,8-
tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD, hereinafter referred to as 
simply dioxin), two External Review Draft documents are being made 
available for a 120-day public review and comment period.

-----------------------------------------------------------------------

SUMMARY: This notice announces the availability of two External Review 
Draft documents for public review and comment:

1. Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
(TCDD) and Related Compounds (EPA/600/BP-92/001a-c)
2. Estimating Exposure to Dioxin-Like Compounds (EPA/600/6-88/005Ca-c)

    During the public comment period, public comment meetings will be 
convened to take formal comments on the draft documents. These meetings 
are being planned for the first two weeks of December at five 
locations: Washington, DC; New York, NY/New Jersey; Chicago, IL; 
Dallas, TX; and San Francisco, CA. Detailed information will be 
provided in a future Federal Register notice.
    The draft documents also will be reviewed at a Science Advisory 
Board meeting to be held after the public comment period has ended, 
early next year. Information about this meeting will be published in a 
future Federal Register notice.

DATES: The draft documents will be made available on September 13, 
1994. Comments must be postmarked by January 13, 1994.

ADDRESSES:

Requesting Documents

    Due to the large size of both draft documents (each is over 1,000 
pages in length), the documents will be available as follows:

Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
(TCDD) and Related Compounds, EPA/600/BP-92/001a, 001b, 001c. (Note: 
The full document is 3 volumes and approx. 1,100 pages.)

      or

Risk Characterization Chapter, EPA/600/BP-92/001c. (Note: This third 
volume of the 3-volume set integrates health and exposure information 
on dioxin and related compounds; approx. 100 pages.)

      and/or

Estimating Exposure to Dioxin-Like Compounds, EPA/600/6-88/005Ca, Cb, 
Cc. (Note: The full document is 3 volumes and approx. 1,300 pages.)

      or

Executive Summary Chapter of the Exposure Document, EPA/600/6-88/005Ca. 
(Note: This first volume of the 3-volume set summarizes the exposure 
information; approx. 100 pages.)

    To obtain a paper copy of these draft documents, interested parties 
should contact the ORD Publications Center, CERI-FRN, U.S. 
Environmental Protection Agency, 26 W. Martin Luther King Drive, 
Cincinnati, OH 45268; telephone (513) 569-7562; fax (513) 569-7566. 
Please provide your name, mailing address, document title, and EPA 
number.
    Please note that the two summary volumes also will be made 
available as WordPerfect 5.1 files on 3\1/2\'' PC-DOS formatted disks. 
Please request by document title and EPA number:
Risk Characterization Chapter (Vol. III-Health), EPA/600/BP-92/001ca 
(disk)
Executive Summary Chapter (Vol. I-Exposure), EPA/600/6-88/005Caa (disk)
    The draft documents will be provided for inspection at the ORD 
Public Information Shelf, EPA Headquarters Library, 401 M Street, S.W., 
Washington, DC 20460, between the hours of 10 a.m. and 2 p.m., Monday 
through Friday, except for Federal holidays, and at all of the EPA 
Regional and Laboratory libraries.

Submitting Comments

    All comments must be in writing. Commenters should submit three 
copies of each comment, and if commenting on both documents--the health 
assessment document and the exposure assessment--submit separate 
comments rather than combined submissions.
    For the health assessment document, send comments to: Dioxin Health 
Assessment Comments, Technical Information Staff (8601), Office of 
Health and Environmental Assessment, U.S. Environmental Protection 
Agency, 401 M Street, S.W., Washington, DC 20460.
    For the exposure assessment document, send comments to: Dioxin 
Exposure Assessment Comments, Technical Information Staff (8601), 
Office of Health and Environmental Assessment, U.S. Environmental 
Protection Agency, 401 M Street, SW., Washington, DC 20460.

FOR FURTHER INFORMATION CONTACT:
For questions on the overall reassessment of dioxin or technical 
questions on the health assessment document: William Farland, Office of 
Health and Environmental Assessment (8601), Office of Research and 
Development, U.S. Environmental Protection Agency, 401 M Street, SW., 
Washington, DC 20460; telephone (202) 260-7315; fax (202) 260-0393.
    For technical questions on the exposure assessment: John Schaum, 
Exposure Assessment Group (8603), Office of Health and Environmental 
Assessment, U.S. Environmental Protection Agency, 401 M Street SW., 
Washington, DC 20460; telephone (202) 260-8909; fax 260-1722.

SUPPLEMENTARY INFORMATION:

The Scientific Reassessment of Dioxin

    In April 1991, EPA announced that it would conduct a scientific 
reassessment of the health risks of exposure to 2,3,7,8-
tetracholorodibenzo-p-dioxin (TCDD) and chemically similar compounds 
collectively known as dioxin. The EPA has undertaken this task in 
response to emerging scientific knowledge of the biological, human 
health, and environmental effects of dioxin. Significant advances have 
occurred in the scientific understanding of mechanisms of dioxin 
toxicity, of the carcinogenic and other adverse health effects of 
dioxin in people, of the pathways to human exposure, and of the toxic 
effects of dioxin to the environment. The reassessment is part of the 
Agency's goals to improve the research and science base and to 
incorporate improved research and science into EPA decisions.

History

    In 1985 and 1988, the Agency prepared assessments of the human 
health risks from environmental exposures to dioxin. Also, in 1988, a 
draft exposure document was prepared that presented procedures for 
conducting site-specific exposure assessments to dioxin-like compounds. 
These assessments were reviewed by the Agency's Science Advisory Board 
(SAB). At the time of the 1988 assessments, there was general agreement 
within the scientific community that there could be a substantial 
improvement over the existing approach to analyzing dose response, but 
there was no consensus as to a more biologically defensible 
methodology. The Agency was asked to explore the development of such a 
method. The Agency's reassessment activities are in response to this 
request.

Stages in the Reassessment Process That Have Been Completed

    The EPA had endeavored to make each phase of the reassessment of 
dioxin an open and participatory effort. On November 15, 1991, and 
April 28, 1992, public meetings were held to discuss the Agency's plans 
and activities for the reassessment, to hear and receive public 
comments and reviews of the proposed plans, and to receive any current, 
scientifically relevant information.
    In the Fall of 1992, the Agency convened two peer-review workshops 
to review draft documents related to EPA's scientific reassessment of 
the health effects of dioxin. The first workshop was held September 10 
and 11, 1992, to review a draft exposure assessment titled, Estimating 
Exposures to Dioxin-Like Compounds. The second workshop was held 
September 22-25, 1992, to review eight chapters of a future draft 
Health Assessment Document for 2,3,7,8-Tetrachlorodibenzo-p-dioxin 
(TCDD) and Related Compounds. Peer-reviewers were also asked to 
identify issues to be incorporated into the risk characterization, 
which was under development.
    In the Fall of 1993, a third peer-review workshop was held on 
September 7 and 8, to review a draft of the revised and expanded 
Epidemiology and Human Data Chapter, which also would be part of the 
future health assessment document. The revised chapter provided an 
evaluation of the scientific quality and strength of the epidemiology 
data in the evaluation of toxic health effects, both cancer and 
noncancer, from exposure to dioxin, with an emphasis on the specific 
congener, 2,3,7,8-TCDD.
    Prior to each workshop, the draft documents or chapters were made 
available in keeping with the Agency's continuing commitment to conduct 
the reassessment of dioxin in an open and participatory manner, to keep 
the public informed of its progress, and to encourage public 
participation in the document development process. The public also was 
invited to attend the workshops, to present oral comments, and/or to 
submit written comments. At each workshop, a panel of scientific 
experts from outside the Agency reviewed the draft documents and 
provided valuable comments. It also should be noted that outside 
scientists have been heavily involved throughout the developmental 
process of writing and reviewing these draft documents. With this 
notice, the External Review Drafts of both draft documents are being 
released for a 120-day public review and comment period.

Current Stage of the Scientific Reassessment of Dioxin

    The scientific reassessment of dioxin consists of five activities:

1. Update and revision of the health assessment document for dioxin.
2. Laboratory research in support of the dose-response model.
3. Development of a biologically based dose-response model for dioxin.
4. Update and revision of the dioxin exposure assessment document.
5. Research to characterize ecological risks in aquatic ecosystems.

    The first four activities have resulted in two draft documents (the 
health assessment document and exposure document) for 2,3,7,8-
tetrachlorodibenzo-p-dioxin (TCDD) and related compounds. These 
companion documents, which form the basis for the Agency's reassessment 
of dioxin, have been used in the development of the risk 
characterization chapter that follows the health assessment (Chapter 9, 
Volume III). The process for developing these documents consisted of 
three phases which are outlined in later paragraphs.
    The fifth activity, which is in progress at EPA's Environmental 
Research Laboratory in Duluth, Minnesota, involves characterizing 
ecological risks in aquatic ecosystems from exposure to dioxins. 
Research efforts are focused on the study of organisms in aquatic food 
webs to identify the effects of dioxin exposure that are likely to 
result in significant population impacts. A report titled, Interim 
Report on Data and Methods for the Assessment of 2,3,7,8-
Tetrachlorodibenzo-p-Dioxin (TCDD) Risks to Aquatic Organisms and 
Associated Wildlife (EPA/600/R-93/055), was published in April 1993. 
This report will serve as a background document for assessing dioxin-
related ecological risks. Ultimately, these data will support the 
development of aquatic life criteria which will aid in the 
implementation of the Clean Water Act.
    As mentioned previously, completion of the health assessment and 
exposure documents involves three phases: Phase 1 involved drafting 
state-of-the-science chapters and a dose-response model for the health 
assessment document, expanding the exposure document to address dioxin 
related compounds, and conducting peer-review workshops by panels of 
experts. This phase has been completed.
    Phase 2, preparation of the risk characterization, began during the 
September 1992 workshops with discussions by the peer-review panels and 
formulation of points to be carried forward into the risk 
characterization. Following the September 1993 workshop, this work was 
completed and was incorporated as Chapter 9 (Volume III) of the draft 
health assessment document. This phase has been completed.
    Phase 3 is currently underway. It includes making External Review 
Drafts of both the health assessment document and the exposure document 
available for public review and comment.

Next Stages in the Reassessment Process

    As described previously, public briefings will be held during the 
first week of the public comment period to be followed by formal public 
hearings in December 1994. After the close of the public comment 
period, the Agency's Science Advisory Board (SAB) will review the draft 
documents in public session (early 1995). Following SAB review, the 
draft documents will be revised, comments and revisions will be 
incorporated, and final documents will be issued.

    Dated: August 30, 1994.
Carl R. Gerber,
Acting Assistant Administrator for Research and Development.
[FR Doc. 94-22442 Filed 9-12-94; 8:45 am]
BILLING CODE 6560-50-P-M