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Land snails are invertebrates ideally located at the interface between soil, plants and air and can therefore be considered as excellent boindicators of metal pollution of terrestrial and atmospheric ecosystems. They are also highly appreciated worldwide for their high nutritional values but can sometimes constitute a health risk for consumers. The land snails Otala lactea and Otala punctata are used in this study because they are the most consumed species in Morocco and the most exported to the international market. They are also relatively abundant and well distributed spatially in the Marrakech region. In this work, these two species were used to assess the levels of some trace elements accumulated in their tissues, then to monitor the quality of some agricultural lands in the Haouz plain. Results showed that these species accumulated all the studied elements with concentrations up to 6.63 µg/g, 15.48 µg/g, 363.67 µg/g, 572.06 µg/g and 442.103 for Pb, Cd, Zn, Cu and Ca respectively. The different statistical analyzes have also shown that these snails are macroconcentrators of Cd and microconcentrators of Pb from the soil and that high levels of MTEs (Pb, Cd, Zn and Cu) are accumulated mainly in the viscera, moderately in the foot and weakly in the shell.
A health risk assessment combining chemical analysis and a field survey of snail consumption practices in Marrakech revealed that snail species such as Otala spp. offer significant nutritional benefits due to their high levels of essential trace elements like zinc (Zn) and copper (Cu). However, their tendency to accumulate cadmium (Cd) at high concentrations presents a potential health risk, particularly for individuals with frequent consumption, such as street vendors or those who prepare snails regularly, with a risk quotient exceeding 1. To reduce exposure to toxic metals - mainly concentrated in the viscera - consumers are advised to eat only the pedal part (foot) of the snails. For occasional consumers, these dishes, including the broth, generally remain a valuable source of essential micronutrients.
Altogether, this research emphasizes the ecological and health-related importance of monitoring edible terrestrial snails. It calls for regulations on wild harvesting, awareness campaigns, and the development of ecological snail farming to ensure food safety and biodiversity conservation in the context of climate-related environmental degradation.
Keywords: land snails, trace metals, bioindicators, air and soil pollution, food safety, public health, ICP-MS, Marrakech.
