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 (R) (active ingredient (a.i.), diquat) and Roundup (R) or its a.i., glyphosate. of a surfactant (Agral (R) 90, a.i., nonylphenol polyethoxylates) and of cadmium (Cd) were studied. Endpoints were the hatching success and observations of embryo abnormalities after exposure. Roundup (R) was found to be more toxic than its a.i. alone (EC50(a.i.) = 18 mg/I and about 1300 mg/I, respectively). Reglone (R) (EC50(a.i.) =0.72 mg/I) and Agral (R) (EC50(a.i.) approximate to 50 mg/I) were also tested together, revealing that Reglone (R) 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/I), 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. (c) 2010 Elsevier B.V. All rights reserved.