Peer Review Workshop-R.A. of Chem. Mixtures

[ttweed@wildrockies.org (Tony Tweedale)]

[Federal Register: May 4, 1999 (Volume 64, Number 85)]
[Notices]
[Page 23833-23834]
>From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr04my99-63]

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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



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