Glyphosate is noted for being non-toxic in fishes, birds and mammals (including humans). Nevertheless, the degree of genotoxicity is seriously controversial. In this work, various concentrations of a glyphosate isopropylamine salt were tested using two methods of genotoxicity assaying, viz., the pink mutation assay with Tradescantia (4430) and the comet assay with nuclei from staminal cells of the same plant. Staminal nuclei were studied in two different forms, namely nuclei from exposed plants, and nuclei exposed directly. Using the pink mutation assay, isopropylamine induced a total or partial loss of color in staminal cells, a fundamental criterion utilized in this test. Consequently, its use is not recommended when studying genotoxicity with agents that produce pallid staminal cells. The comet assay system detected statistically significant (p < 0.01) genotoxic activity by isopropylamine, when compared to the negative control in both the nuclei of treated plants and directly treated nuclei, but only the treated nuclei showed a dose-dependent increase. Average migration in the nuclei of treated plants increased, when compared to that in treated nuclei. This was probably due, either to the permanence of isopropylamine in inflorescences, or to the presence of secondary metabolites. In conclusion, isopropylamine possesses strong genotoxic activity, but its detection can vary depending on the test systems used.

The genotoxic activity of various concentrations of the marvel herbicide (0.76 μg/1 ml, 7.68 μg/1 ml, 76.8 μg/1 ml, 768 μg/1 ml) was evaluated in lymphocytes of humans and in Balb/c strain mice, as well as in erythrocytes of tilapia (Oreochromis niloticus). They were exposed to each of the concentrations for 6 h, and then genetic damage was evaluated using the comet assay. All concentrations tested induced significant genetic damage compared to the negative control (p < 0.01). On the other hand, there were no differences between the blood cells of the organisms studied. Tail length and tail moment increased starting from 0.76 μg/1 ml concentration, which is the lowest concentration reported to cause any genetic damage. Data suggest that the reported differences regarding the genotoxicity of marvel and its active ingredients are due to the marked differences between the concentrations studied and the adjuvants present in the commercial formulations.