Repeated exposure to cyclopentenone vapour: long-term study in Syrian golden hamsters.

Effects of cyclopentenone inhalation were examined in a 78-week study with 420 hamsters evenly distributed over two inhalation chambers, one for exposure to air and the other for exposure to the test substance. Cyclopentenone was dosed at a level of 18 ppm (seven hr/day, five days/week) during the first 52 weeks, and at a level of 27 ppm during the last 26 weeks of the study. During the first 52 weeks, part of the animals in both chambers fortnightly received an intratracheal instillation of benzo(a)pyrene (BP) or diethylnitrosamine (DENA) in saline or saline alone. Exposure to cyclopentenone caused slight growth depression in both sexes, and slightly increased relative liver weights and enhanced development of renal amyloidosis in females only. There was no evidence of cyclopentenonne possessing carcinogenic activity or being a co-factor in respiratory tract carcinogenesis.