Landsnail eggs bioassays: A new tool to assess embryotoxicity of contaminants in the solid, liquid or gaseous phase of soil

Bioassays for ecotoxicity testing for the same non-target soil organism are not currently available for contaminants that can be present in the liquid, solid or gaseous phase of soil. Here, three bioassays with three modes (liquid, solid or gaseous phase, LPB, SPB and GPB, respectively) allowing the assessment of the embryotoxicity of chemicals or pluri-contaminated matrices on land snail eggs are presented. Eight pesticides commonly used in vineyards (based on 10 active ingredients: copper, sulfur, metiram-zinc + pyraclostrobin, cymoxanil + folpet + fosetyl-Aluminium, tebuconazole, glyphosate, glufosinate) were tested by LPB: all of them reduced egg hatching success at concentrations lower than those applied in the field. The SPB was developed with one artificial ISO substrate and seven natural soils: three non-contaminated agricultural soils (Agr1-3) and four metal-contaminated soils (Me1-4). The moisture content (from 40 to 60% of the water holding capacity) in the natural soils did not influence the hatching success. Hatching success did not vary in the three agricultural soils suggesting the relative insensitivity of eggs to some soil properties. Among the two pesticides tested in SPB, Corail (R) (tebuconazole based-fungicide) was more toxic than Bypass (R) (glyphosate based-herbicide) to snail embryos with EC50 values of 1 and 219 mg kg(-1) respectively in a natural soil (Agr2). Both pesticides were less toxic when tested in the ISO substrate (EC50 of 7.8 and higher than 400 mg kg(-1), respectively for Corail (R) and Bypass (R)), highlighting the influence of the organic matter content (lower in soil Agr2) on the bioavailability and thus the toxicity of the chemicals. LPB showed that soluble compounds of the most toxic soil in SPB (Me4) did not affect embryos. Similarly, GPB did not reveal toxic volatile compounds from this soil. These bioassays are complementary and efficient tools for soil risk assessment. (c) 2011 Elsevier B.V. All rights reserved.