[Federal Register Volume 59, Number 178 (Thursday, September 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22816]


[[Page Unknown]]

[Federal Register: September 15, 1994]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

National Toxicology Program; Availability of Technical Report on 
Toxicology and Carcinogenesis Studies of Hexachlorocyclopentadiene

    The HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the toxicology and carcinogenesis studies 
of hexachlorocyclopentadiene, an intermediate used in the manufacture 
of flame retardants, resins, and chlorinated cyclodiene pesticides.
    Toxicology and carcinogenesis studies were conducted by exposing 
groups of 60 male and female F344/N rats and B6C3F1 mice to 
atmospheres containing 0, 0.01, 0.05, or 0.2 ppm 
hexachlorocyclopentadiene (approximately 98% pure) for 2 years.
    Under the conditions of these 2-year studies, there was no evidence 
of carcinogenic activity\1\ of hexachlorocyclopentadiene in male or 
female F344/N rats or B6C3F1 mice exposed to 0.01, 0.05, or 0.2 
ppm.
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    \1\The NTP uses five categories of evidence of carcinogenic 
activity observed in each animal study: two categories for positive 
results (``clear evidence'' and ``some evidence''), one category for 
uncertain findings (``equivocal evidence''), one category for no 
observable effect (``no evidence''), and one category for studies 
that cannot be evaluated because of major flaws (``inadequate 
study'').
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    Exposure of rats to hexachlorocyclopentadiene produced pigmentation 
of the respiratory epithelium of the nose, trachea (males), and bronchi 
and bronchioles of the lung. Squamous metaplasia of the laryngeal 
epithelium occurred in female rats exposed to 
hexachlorocyclopentadiene. Suppurative inflammation of the nose as well 
as pigmentation of the respiratory mucosal epithelium occurred in mice 
exposed to hexachlorocyclopentadiene.
    Questions or comments about the Technical Report should be directed 
to Central Data Management at P.O. Box 12233, Research Triangle Park, 
NC 27709 or telephone (919) 541-3419.
    Copies of Toxicology and Carcinogenesis Studies of 
Hexachlorocyclopentadiene (CAS No. 77-47-4) in F344/N Rats and 
B6C3F1 Mice (Inhalation Studies) (TR-437) are available without 
charge from Central Data Management, NIEHS, MD A0-01, P.O. Box 12233, 
Research Triangle Park, NC 27709; telephone (919) 541-3419.

    Dated: September 8, 1994.
Kenneth Olden,
Director, National Toxicology Program.
[FR Doc. 94-22816 Filed 9-14-94; 8:45 am]
BILLING CODE 4140-01-M