In vitro effects of N-nitrosoatrazine on chromosome breakage.

Exposing human lymphocyte cultures to concentrations of N-nitrosoatrazine (NNAT) as low as 0.0001 microgram/ml results in significant elevations in chromosome breakage as well as an increased mitotic index. In contrast, 1,000-10,000-fold greater concentrations of nitrates, nitrites, and/or atrazine was required to produce comparable chromosome damage and, in those cases where the mitotic index was affected, it was decreased. Simultaneous administration of nitrates or nitrites with atrazine caused less chromosome damage than low concentrations of NNAT without affecting the mitotic index, illustrating that metabolic conversion of contaminants with minimal genotoxicity can give rise to compounds such as NNAT which are even more genotoxic.