Towards the development of an embryotoxicity bioassay with terrestrial snails: Screening approach for cadmium and pesticides

Currently no bioassays are available to assess the embryotoxicity of chemicals with terrestrial soil invertebrates. We therefore presented a new method for embryotoxicity testing with snail eggs: a relevant biological material that incubates in soil and that can be exposed to contaminants from leachates and soil solution. The effects of aqueous solutions of two herbicide formulations, Reglone® (active ingredient (a.i.), diquat) and Roundup® or its a.i., glyphosate, of a surfactant (Agral® 90, a.i., nonylphenol polyethoxylates) and of cadmium (Cd) were studied. Endpoints were the hatching success and observations of embryo abnormalities after exposure. Roundup® was found to be more toxic than its a.i. alone (EC50a.i. = 18 mg/l and about 1300 mg/l, respectively). Reglone® (EC50a.i. = 0.72 mg/l) and Agral® (EC50a.i. ≈ 50 mg/l) were also tested together, revealing that Reglone® accounted for more than 99% of the mixture's toxicity. An antagonistic interaction between the two substances was found. For Cd (EC50 = 3.9 mg/l), a significant transfer from exposure medium to eggs was emphasized, particularly affecting the albumen. Abnormalities of embryogenesis in non-hatched embryos depended on the substance and the concentration considered.