[Federal Register Volume 67, Number 210 (Wednesday, October 30, 2002)]
[Notices]
[Pages 66151-66152]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-27625]


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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: [email protected].

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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