Effects of dose on the induction of dominant-lethal mutations with triethylenemelamine in male mice.

Dose effects of triethylenemelamine (TEM) in the induction of dominant-lethal mutations were studied at the early spermatozoon, midspermatid and spermatocyte stages. The pattern of effects on spermatocytes, unlike midspermatids and early spermatozoa, indicated possible cytotoxic damage, so for the determination of TEM dose-response curves in the induction of genetic damage only the data for midspermatids and early spermatozoa were used. The TEM dose-effect curves for those two stages differ markedly from ethyl methanesulfonate (EMS) dose-effect curves. Beginning with the lowest doses at which significant effects are observed, there is a considerably more rapid increase in dominant-lethal effects with dose of EMS than TEM. Another marked difference between the two compounds is in the ratio of the genetically effective dose (as measured by dominant-lethal mutations) to the lethal dose. The ratio is 1:100 for TEM and only 1:3.5 for EMS; thus, TEM is mutagenic far below its toxic level. Obviously, these results have important implications not only for our understanding of the nature of chemical induction and recovery of chromosomal aberrations but also for the practical problems of evaluating the mutagenic effects of chemicals.