Evaluation of the genotoxicity of n-nitrosoatrazine, n-nitrosodiethanolamine and their precursors in vivo using the newt micronucleus test

Abstract

The impact of amines and/or potential nitrosating agents (nitrite and nitrate) present in water was studied in the amphibian Pleurodeles waltl (urodele). The genotoxic effects of secondary amines, atrazine (AT) and diethanolamine (DEIA), alone or in combination with sodium nitrite or sodium nitrate, were evaluated on peripheral erythrocytes using the newt micronucleus test. At the maximum concentration (MC) which could be tested, neither AT (0.3 ppm) nor DEIA (75 ppm) were found to be clastogenic. Likewise, even at their respective MC, neither sodium nitrite (140 ppm) nor sodium nitrate (8000 ppm) induced the formation of micronuclei. Negative results were systematically obtained under all conditions examined (pH 8, 6 or 5; alternation or indirect natural daylight and darkness or continuous darkness; prior incubation of both precursors in the dark for 48 h). The genotoxic effects of N-nitrosamines suspected to be formed from such precursors were also evaluated. Larvae were reared in water containing non-toxic concentrations of N-nitrosoatrazine (NAT) (3.75, 7.5 and 15 ppm) or N-nitrosodiethanolamine (NDEIA) (6.25, 12.5, 25 and 50 ppm). We found a significant difference in level of micronucleated erythrocytes between the lowest (3.75 ppm) and highest (15 ppm) concentrations of NAT. With NDEIA, a dose-response relationship was observed at concentrations from 12.5 to 50 ppm. We suggest that at the concentrations used (close to those which may be encountered in a polluted natural aquatic environment), if NAT or NDEIA are formed, the amounts produced are probably too low to yield a positive response in the newt micronucleus test.