In addition, earthworm vulnerability to soil pollutants was described using five traits selected a priori in terms of exposure, sensitivity and population recovery ( Table 3).
Body pigmentation was proposed as a proxy for exposure. Surface earthworms, which are more deeply coloured, are the first to be exposed to pollutants that enter the soil.
Sensitivity to exposure by contact was supposed to decrease with body wall thickness and exposure by ingestion was assessed by studying predominant earthworm food geophagous earthworms were considered more exposed than earthworms feeding on organic matter.
Population recovery ability was assessed by species reproductive strategy and rate of occurrence in France.