Methods for toxicity assessment of contaminated soil by oral or dermal uptake in land snails. 1. Sublethal effects on growth

Among the terrestrial invertebrate fauna, snails are primary consumers. Sublethal (4 weeks) bioassays using Helix aspersa aspersa (Haa) and Helix aspersa maxima (Ham) have been established to evaluate the potential impact of pollutants present in the soil via oral and dermal exposure through measurement of a biologically important, sublethal endpoint: growth. In both subspecies, trace elements (Cd, Cr, Pb, and Zn) in a contaminated soil (S1) administered orally, exerted dose dependent inhibition of growth. On dermal uptake (spraying the snails with leachate of soil S1), however, Haa appeared unaffected, whereas Ham showed a slight inhibition of growth. After contamination with organic substances (phenanthrene, trichlorophenol, pentachlorophenol), soil S2 reduced the growth of Haa (oral: +++; dermal: ++), whereas Ham were not inhibited by dermal exposure and only affected by dietary exposure at very high doses. The methods proposed represent a new tool for soil risk assessment by two distinct exposure routes: oral and dermal.