[Federal Register Volume 64, Number 85 (Tuesday, May 4, 1999)]
[Notices]
[Pages 23833-23834]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-11167]


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ENVIRONMENTAL PROTECTION AGENCY

[FRL-6335-6]


Peer Review Workshop on Guidance for Conducting Health Risk 
Assessment of Chemical Mixtures

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of meeting.

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SUMMARY: The EPA Risk Assessment Forum (Forum) is announcing a peer 
review workshop convened by Eastern Research Group, Inc., an EPA 
contractor, for scientific peer review of the EPA draft document 
Guidance for Conducting Health Risk Assessment of Chemical Mixtures. 
The workshop will be held in Cincinnati, Ohio, and will be open to 
members of the public as observers. The peer review, to be conducted by 
scientists from outside EPA, is being organized to review the 
procedures and related issues presented in the document Guidance for 
Conducting Health Risk Assessment of Chemical Mixtures. The Forum 
Technical Panel will consider the opinions of experts outside the 
Agency in finalizing the document.

DATES: The workshop will begin on Thursday, May 20, 1999 at 9:00 a.m. 
and end on Friday, May 21, 1999 at 4:00 p.m. Members of the public may 
attend as observers.

ADDRESSES: The meeting will be held at the U.S. Environmental 
Protection Agency (EPA) Briedenbach Research Center, 26 West Martin 
Luther King Drive, Cincinnati, Ohio 45268. Since seating capacity is 
limited, please contact Eastern Research Group, Inc., Tel.: (781) 674-
7374, by May 14, 1999 to attend the workshop as an observer.

FOR FURTHER INFORMATION CONTACT: For technical inquires, contact Dr. 
Richard Hertzberg, U.S. EPA Region 4, 10th Floor WMD, 61 Forsyth 
Street, S.W., Atlanta, Georgia 30303-3104. Tel.: (404)562-8663. The 
document will be Internet-accessible from the Risk Assessment Forum 
publications page, at http://www.epa.gov/ncea/raf/rafpub.htm. Inquiries 
concerning the workshop should be directed to Eastern Research Group, 
Inc.

SUPPLEMENTARY INFORMATION: To address concerns over health risks from 
multichemical exposures, the U.S. EPA issued Guidelines for Health Risk 
from Exposure to Chemical Mixtures in 1986 (U.S. EPA, 1986). Those 
Guidelines described broad concepts related to mixtures exposure and 
toxicity and included few specific procedures. In 1989, the U.S. EPA 
published guidance for the Superfund program on hazardous waste that 
gave practical steps for conducting a mixtures risk assessment (U.S. 
EPA, 1989). Also in 1989, the U.S. EPA published the revised document 
on the use of Toxicity Equivalence Factors for characterizing health 
risks of the class of chemicals including the dibenzo-dioxins and 
dibenzofurans. In 1990, the U.S. EPA published a Technical Support 
Document to provide more detailed information on toxicity of whole 
mixtures and on toxicologic interactions (e.g., synergism) between 
chemicals in a binary (two-chemical) mixture (U.S. EPA, 1990). The 
concept of toxicologic similarity was also discussed.

[[Page 23834]]

    This guidance document, Guidance for Conducting Health Risk 
Assessment of Chemical Mixtures, represents a supplement to the 
original Guidelines of 1986 and is intended to reflect the evolutionary 
scientific development in the area of chemical mixtures risk 
assessment. Consequently, many of the former discussions have been 
reiterated. New guidance has been provided that gives more specific 
details on the nature of the desired information and the procedures to 
use in analyzing the data. This supplement to the earlier guidances is 
organized according to the type of data available to the risk assessor, 
ranging from data rich to data poor situations. Procedures are 
described for assessment using data on the mixture of concern, data on 
a toxicologically related mixture, as well as data on the mixture 
component chemicals. The state of science varies dramatically for these 
three approaches. No single approach is recommended in this 
supplementary guidance. Instead, guidance is given for the use of 
several approaches depending on the nature and quality of the data. 
Although several of the procedures described in the guidance have not 
yet been applied in actual health risk assessments, their use and the 
generation of data to support their use is encouraged, along with 
research on new procedures to improve or replace those discussed. As 
new information relevant to health risk from exposure to chemical 
mixtures becomes available, additional guidance documents will be 
published. Following the external peer review, reviewers' comments will 
be addressed and the revised guidance will undergo Risk Assessment 
Forum final review.

    Dated: April 26, 1999.
William H. Farland,
Director, National Center for Environmental Assessment.
[FR Doc. 99-11167 Filed 5-3-99; 8:45 am]
BILLING CODE 6560-50-P