Carcinogenic and cocarcinogenic potential of cypermethrin on mouse skin

Cypermethrin (CYM), a synthetic pyrethroid insecticide, is used widely because of its high bio-efficacy and low mammalian toxicity. In the present set of investigations, CYM has been evaluated for it's carcinogenic and co-carcinogenic (tumour initiating and tumour promoting) potential in mouse skin model of carcinogenesis. The results revealed that CYM possess complete carcinogenic as well as tumour initiating and promoting potential in both the sexes of Swiss albino mice. At the end point, i.e. 32 weeks in a single dose (10 mg/kg body weight (wt.), once only), initiated mice, 9 out of 12 surviving males, and 10 out of 14 surviving females developed benign tumours, while a higher incidence of tumourigenesis was recorded in multiple dose-initiated (10 mg/kg body wt., total nine applications) group, where 7 out of 9 surviving male and 10 out of 13 surviving female mice developed tumours at the site of topical exposure. The application of CYM as a tumour promoter on 7,12-dimethylbenz(a)anthracene initiated animals induced tumour incidence in about 4 out of surviving 10 male and 5 out of surviving 13 female Swiss albino mice. CYM when tested for complete carcinogenic activity induced tumour formation in both male and female animals at all the three tested dose levels.