Fenitrothion. I. Study of mutagenic activity in rats

The mutagenic activity of fenitrothion was studied in rats given 0,10,40 or 80 ppm of fenitrothion in the diet. The study combined the dominant lethal test with cytogenetic analysis of chromosomal aberrations. Dominant lethal mutations were investigated: 1. by their so-called tentative determination in single mating in P-to F3 generation males and females following 200 days exposure; 2. by assessing the effect of the agent at individual stages of spermatogenesis, with F2 and F4 generation males having been exposed for 100 days and mated to unexposed females for 10 weeks. Chromosome aberrations were analyzed in the bone marrow of F2 generation males following 200-days exposure and F3 generation (males) following 500-day exposure to a dose of 80 ppm. Negative results were obtained in all experiments in relation both to dose and generation. Hence fenitrothion is not considered to be a substance with a mutagenic activity. The metodical advantages of the proposed combination of reproduction and mutagenic-activity studies of an agent for toxicological evaluation are discussed.