National Toxicology Program

DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service

National Toxicology Program (NTP); 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/m³) 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/m³) 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 * 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/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.

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 or send e-mail to CDM@niehs.nih.gov.

Dated: August 21, 1996

 
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Kenneth Olden, Ph.D.
Director
National Toxicology Program

[Billing Code 4140-01]

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*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").