[Federal Register Volume 61, Number 188 (Thursday, September 26, 1996)]
[Notices]
[Pages 50500-50501]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-24627]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

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

    The HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the toxicology and carcinogenesis studies 
of acetonitrile. Acetonitrile is used primarily as a solvent in 
extractive distillation and crystallization of pharmaceutical and 
agricultural products and as a catalyst in chemical reactions.
    Toxicology and carcinogenicity studies were conducted by 
administration of acetonitrile by inhalation to groups of 56 F344/N 
rats of each sex at doses of 0, 100, 200, or 400 ppm (equivalent to 0, 
168, 335, or 670 mg/m\3\) and 60 B6C3F1 mice of each sex were 
exposed at doses of 0, 50, 100, or 200 ppm (equivalent to 0, 84, 168, 
or 335 mg/m\3\) for 6 hours per day, 5 days per week for 2 years.
    Under the conditions of these 2-year inhalation studies, there was 
equivocal evidence of carcinogenic activity \1\ of acetonitrile in male 
F344/N rats based on marginally increased incidences of hepatocellular 
adenoma and carcinoma. There was no evidence of carcinogenic activity 
of acetonitrile in female F344/

[[Page 50501]]

N rats exposed to 100, 200, or 400 ppm. There was no evidence of 
carcinogenic activity of acetonitrile in male or female B6C3F1 
mice exposed to 50, 100, or 200 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 to acetonitrile by inhalation resulted in increased 
incidences of hepatic basophilic foci in male rats and of squamous 
hyperplasia of the forestomach in male and female mice.
    Questions or comments about the Technical Report should be directed 
to Central Data Management at MD E1-02, P.O. Box 12233, Research 
Triangle Park, NC 27709-2233 or telephone (919) 541-3419.
    Copies of Toxicology and Carcinogenesis Studies of Acetonitrile 
(CAS No. 75-05-8) (TR-447) are available without charge from Central 
Data Management, NIEHS, MD E1-02, P.O. Box 12233, Research Triangle 
Park, NC 27709; telephone (919) 541-3419.

    Dated: August 21, 1996.
Kenneth Olden,
Director, National Toxicology Program.
[FR Doc. 96-24627 Filed 9-25-96; 8:45 am]
BILLING CODE 4140-01-M