[Federal Register: October 30, 2002 (Volume 67, Number 210)]
[Notices]
[Page 66151-66152]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr30oc02-69]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-7402-2]
Health Assessment of 1,3-Butadiene
AGENCY: Environmental Protection Agency.
ACTION: Notice of Availability.
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SUMMARY: This notice announces the availability of a final report
titled, Health Assessment of 1,3-Butadiene (EPA/600/P-98/001F), which
was prepared by the U.S. Environmental Protection Agency's (EPA)
National Center for Environmental Assessment (NCEA) of the Office of
Research and Development (ORD).
DATES: This document will be available on or about October 30, 2002.
ADDRESSES: The document will be made available electronically through
the NCEA Web site (http://www.epa.gov/ncea). A limited number of paper
copies will be available from the EPA's National Service Center for
Environmental Publications (NSCEP), P.O. Box 42419, Cincinnati, OH
45242; telephone: 1-800-490-9198 or 513-489-8190; facsimile: 513-489-
8695. Please provide your name, your mailing address, the title and the
EPA number of the requested publication.
[[Page 66152]]
FOR FURTHER INFORMATION CONTACT: The Technical Information Staff,
National Center for Environmental Assessment/Washington Office (8623D),
U.S. Environmental Protection Agency, 1200 Pennsylvania Avenue, NW.,
Washington, DC 20460. Telephone: 202-564-3261; fax: 202-565-0050; e-
mail: nceadc.comment@epa.gov.
SUPPLEMENTARY INFORMATION: This assessment was conducted to review the
new information that has become available since EPA's 1985 health
assessment of 1,3-butadiene.
1,3-Butadiene is a gas used commercially in the production of
styrene-butadiene rubber, plastics, and thermoplastic resins. The major
environmental source of 1,3-butadiene is the incomplete combustion of
fuels from mobile sources (e.g., automobile exhaust). Tobacco smoke can
be a significant source of 1,3-butadiene in indoor air.
This assessment concludes that 1,3-butadiene is carcinogenic to
humans by inhalation, based on the total weight of evidence. The
specific mechanisms of 1,3-butadiene-induced carcinogenesis are
unknown, however, it is virtually certain that the carcinogenic effects
are mediated by genotoxic metabolites of 1,3-butadiene.
Animal data suggest that females may be more sensitive than males
for cancer effects; nevertheless, there are insufficient data from
which to draw any conclusions on potentially sensitive subpopulations.
The human incremental lifetime unit cancer (incidence) risk
estimate is based on extrapolation from leukemias observed in an
occupational epidemiologic study. A twofold adjustment to the
epidemiologic-based unit cancer risk is then applied to reflect
evidence from the rodent bioassays suggesting that the epidemiologic-
based estimate may underestimate total cancer risk from 1,3-butadiene
exposure in the general population.
1,3-Butadiene also causes a variety of reproductive and
developmental effects in mice; no human data on these effects are
available. The most sensitive effect was ovarian atrophy observed in a
lifetime bioassay of female mice. Based on this critical effect and
using the benchmark concentration methodology, an RfC (i.e., a chronic
exposure level presumed to be ``without appreciable risk'' for
noncancer effects) was calculated.
Dated: October 23, 2002.
Paul Gilman,
Assistant Administrator, Office of Research and Development.
[FR Doc. 02-27625 Filed 10-29-02; 8:45 am]
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