Aim and Background. Environmental protection requires taking into account the genotoxic hazards likely to concern different populations of ecosystems. Genotoxins are substances that cause heritable changes in the genetic material in germ cells, namely spermatocytes or oocytes. Since such hazards may emerge within waters, it is essential to assess them by means of laboratory tests that allow the evaluation, within aqueous environments of the genotoxicity of a water effluent substance or preparation with respect to organisms living in aquatic environments. This article describes a method that is likely to provide information in this field.

Material and Methods. Within aqueous environments it highlights, the genotoxic effects on larvaes of the amphibian species, Xenopus laevis. Xenopus laevis is a species of South African aquatic frog of the genus Xenopus. African clawed frogs can grow up to a length of 12 cm. They have a flattened head and body, but no tongue or external ears. The tested organisms were exposed to a range of concentrations for 12 days. Results. The negative and positive controls were carried out in parallel under the same conditions. The positive control allows the quality of the biological reagent to be checked and the test to be validated. The rate of erythrocytes with micronuclei was determined for each test concentration and control solutions. The rate of erythrocytes with micronuclei for each concentration was compared to that of the negative control in order to determine the concentrations that induce a positive genotoxic effect.

Conclusion. The positivity of a test can be based on the detection, with respect to the negative control, of a statistically significant response for at least one of the test concentrations and the maximum concentration which does not give rise to an acute toxicity has been determined and tested.