Tumourigenic studies on deltamethrin in Swiss albino mice

Deltamethrin, an alpha-cyano type II synthetic pyrethroid insecticide is used to control a wide range of insects on a variety of crops. Deltamethrin is reported to cause many adverse effects on non-target species. Deltamethrin is reported to cause DNA damage and micronuclei induction in human lymphocytes. It is highly toxic for other organisms such as aquatic invertebrates, fish and Daphnia. About the tumorigenic risk (both tumour initiating and promoting) associated with deltamethrin exposure, very few reports are available in literature. In the present set of investigations, deltamethrin has been evaluated for its tumorigenic and co-carcinogenic (tumour initiating and tumour promoting) potential following long term dermal exposure in Swiss albino mice. The results revealed that deltamethrin has only tumour initiating potential in both the sexes of Swiss albino mice, initiated with deltamethrin and promoted by standard tumour promoter, 12-O-tetra decanoyl phorbol-13-acetate (TPA). In the single dose initiated mice (deltamethrin 4 mg/kg body weight, once only), 44% males and 43% females developed benign skin tumours. A much higher incidence of tumorigenesis was recorded in multiple dose initiated animals (deltamethrin 4 mg/kg body weight, three times per week for 3 weeks), where 71% male and 75% female mice developed tumours at the site of application of deltamethrin. Deltamethrin exposure failed to show any tumour promoting and complete tumorigenic potential at all the three tested dose levels.