How terrestrial snails can be used in risk assessment of soils

Abstract

Among soil invertebrates, terrestrial snails are herbivorous and detritivorous organisms exposed to polluted soils by both digestive and cutaneous routes. Using laboratory-reared snails (Helix aspersa aspersa), we describe how the effects of contaminants on survival and growth of snails can be evaluated in laboratory bioassays. A national ring test was performed to assess the effect of Cd added to the soil or to the food. The ecotoxicity of sewage sludge also was evaluated. The present results demonstrate that toxicity depends on both the pollutants and the exposure route. Cadmium was sixfold more toxic for snails exposed via food contamination (median effective concentration [EC50], 68-139 microg/g) than via soil contamination (EC50, 534-877 microg/g), whereas the opposite occurred with the sewage sludge (EC50, 55% of sludge in the food and 10% of waste in the soil). A logistic relationship linked growth inhibition and internal Cd concentrations, which can reach 2,000 microg/g in the viscera of snails exposed to 626 microg/g in the food. No clear trend was found between Cu, Zn, Pb, Cr, and Ni concentrations in the sludge and in snail tissues. These data enabled the development of an international standard, which should enhance the use of terrestrial gastropods for both fundamental research and routine risk assessment in the terrestrial environment.

Bioaccumulative and conchological assessment of heavy metal transfer in a soil-plant-snail food chain

“…Besides these two HM pairs, there were also significant correlations between the whole body Pb and Zn concentrations (r = 0.59-0.65, p < 0.001) as well as between Cu-Zn and Pb-Zn pairs for the whole body without hepatopancreas (r = 0.20-0.73, 0.05 < p < 0.001) [21]. In addition to the exposure to HMs via food uptake, land snails regularly eat soil and they are also exposed to HMs via epithelial contact [40]. As a result, future studies should be designed to verify our hypothesis and to elucidate such complex interactions between HMs during their transfer in the biota.…”

“…Terrestrial gastropods regularly eat soil [40], and therefore, they accumulate heavy metals not only via food from the food chain, but also via contaminated soil. Because Helix pomatia spends its entire life on or in the upper soil horizons, for each location the soil samples were collected (25 g/sample in triplicate) from the top 15 cm layer after removal of vegetation (grass).…”

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

“…However, all these examples concern the aquatic environment because terrestrial bioassays with soil invertebrates are rare: we found only one experiment on a pest slug, reporting the high sensitivity of the embryos to metal salts [51]. Methods on this part of the life cycle would complete existing bioassays for the assessment of chemicals on snail survival, growth and reproduction [2,11,52] and, more generally, terrestrial bioassays used for risk assessment, such as tests on nematodes [5], earthworms [53], honeybee larvae [54,55] or birds [56].…”

Transfer of elements relevant to nuclear fuel cycle from soil to boreal plants and animals in experimental meso- and microcosms

“…Copse snails (Arianta arbostorum) are known to be both herbivorous and detritivorous organisms that can be exposed to contaminated soils by both digestive and cutaneous routes. Snails are also regarded as key components of terrestrial food webs, and they may contribute to the transfer of pollutants from soil and plants to top predators (de Vaufleury et al, 2006). Earthworms are commonly tested in bioaccumulation studies, because they have a high exposure potential to chemicals in soil, and are important part of diet to a variety of wildlife species (DeForest et al, 2011).…”