The snail Theba pisana as an indicator of soil contamination by trace elements: potential exposure for animals and humans.

BACKGROUND

The ability of snails to accumulate trace elements is well known. We analysed the snail Theba pisana as an indicator of soil contamination by trace elements after a mine spill accident, to assess the exposure of animal and human consumption. Snails were collected in autumn and spring, when they are most active.

RESULTS

In general, trace elements in the soft tissues reached greater concentrations in the contaminated soils than in the non-contaminated soils, although significant differences were only found for As, Cd, Cu Fe and Hg. Cadmium content in tissues, with a maximum value of 10 mg kg⁻¹ (dry matter), was the most worrying result. Trace element concentrations in the snail bodies were still of concern for human consumption; As and Cd concentrations were sometimes higher than the maximum concentration authorised in foodstuffs. Generally, nutritional status of the contaminated snails was not altered; concentrations of the main nutrients (Ca, K, Mg, P and S) were similar to those of the non-contaminated snails.

CONCLUSIONS

Results reveal a potential risk for animal and human consumption of T. pisana. It seems thus advisable to avoid collecting this species for human consumption in the affected area. Periodic monitoring is recommended to assess the evolution of potential risk for animal consumption.