Toxicity of sodium arsenite in mouse embryos in vitro and its influence on radiation risk.

Mouse embryos at the preimplantation stage were used in vitro for assessing the risk exerted by arsenic on early stages of embryonal development. We studied the effects of sodium arsenite on morphological development, proliferation, and micronucleus formation. A concentration of 100 microM sodium arsenite immediately killed the embryos, and 1 microM almost completely inhibited formation of blastocysts. Micronuclei were induced starting from 0.7 microM arsenite. Concentrations below 0.1 microM (0.1 microM corresponds to 7.5 ppm arsenic) did not show significant effects with respect to any of the end-points examined. Arsenic did not influence radiation risk under various experimental conditions; all the effects after combining moderately toxic doses of sodium arsenite and X-rays corresponded to the effect obtained by the addition of the single effects.