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Carcinogenicity

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Description of key information

Reliable animal studies do not indicate that acetonitrile is carcinogenic in rats or mice.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Endpoint conclusion
Endpoint conclusion:
no study available

Carcinogenicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:
High quality US NTP carcinogenicity studies are available in the rat and mouse

Carcinogenicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

US NTP inhalation carcinogenicity studies are available for acetonitrile in the rat and mouse.

Inhalation exposure to the maximum tolerated dose of acetonitrile vapour for 2 years did not produce evidence of carcinogenic activity in male or female F344/N rats. NTP concluded equivocal evidence of carcinogenic activity in male F344/N rats based on a marginal increase in the incidence of liver neoplasms at the highest dose (400 ppm). Groups of 56 male and 56 female rats were exposed to 0, 100, 200 or 400 ppm acetonitrile vapour on 6 hours per day, 5 days per week for 2 years. The survival of male animals exposed to 400 ppm was greater than that in the control group (e.g. 12/56 controls and 21/56 400 ppm animals survived to the end of the study). The first liver neoplasms were noted after about 90 weeks, at this time 31/56 controls were surviving, compared to 37/56 at 400 ppm. Neoplasms in the 400 ppm group were typically noted for the longer survivors (e.g. 5/6 tumours were noted in animals that were 727-733 days on the study). No significant dose-related trend was present after incidences were adjusted for survival using the life table test (US EPA, 1999). Two-year survival, mean body weights, organ weights, behaviour, general health, and appearance of male and female rats exposed to acetonitrile were similar to those of the controls. At 15 months, minimal anaemia was noted in female rats exposed to 400 ppm. The hematologic effects observed were minor and considered of no biological significance. The incidence of basophilic hepatic foci in 200 and 400 ppm males were statistically increased, but the foci were not atypical in appearance and are not considered evidence of a hepatotoxic effect. Based on these findings the chronic NOAEC for acetonitrile vapour in rats is considered to be 400 ppm (672 mg/m3).

Inhalation exposure to the maximum tolerated dose of acetonitrile vapour for 2 years produced no evidence of carcinogenic activity in male or female B6C3F1 mice. Groups of 60 male and 60 female mice were exposed to 0, 50, 100 or 200 ppm acetonitrile vapour 6 hours per day, 5 days per week for 2 years. Two-year survival of exposed male and female mice was similar to that of the controls, except that the survival of male mice in the 200 ppm group was significantly greater than that of the controls. Mean body weights and organ weights of exposed groups were similar to those of the controls, and no clinical observations in any group were clearly related to acetonitrile exposure.

In summary, the results of the NTP bioassay on acetonitrile do not indicate that acetonitrile was carcinogenic in laboratory rats or mice.


Justification for selection of carcinogenicity via inhalation route endpoint:
A weight of evidence approach is taken to this endpoint.

Justification for classification or non-classification

No classification of acetonitrile is proposed for carcinogenicity based upon the results of reliable chronic studies in rats and mice.