TRACE ELEMENT BIOACCUMULATION IN THE EDIBLE MILK SNAIL (OTALA LACTEA) AND CABRILLA (OTALA PUNCTATA) IN MARRAKECH, MOROCCO

Abstract

Morocco is the first land snail exporter in the world and the majority of snail production consists of individuals collected from nature. These gastropods are known to accumulate high levels of trace metals in their tissues hence the main objective of this study. We aimed firstly to investigate the bioaccumulation efficiency of Pb, Cd, Zn, Cu and Ca in Otala spp. snails, the most commonly widespread and the most consumed species in the Marrakech region, and then evaluate the potential risk on human health. Soil, foot, viscera and shell of adult snails were picked from six sampling stations in Al Haouz plain and analysed by ICP-MS. Results showed that the investigated snails accumulated all the examined elements with significant variations among the different tissues. The Principal Component and Bioaccumulation Factor analyses demonstrated that Otala spp. are macroconcentrators for Cd and microconcentrators for Pb. Furthermore, their shell accumulated more Ca, foot accumulated more Cu and viscera accumulated more Zn, Cd and Pb. In addition, the detected concentrations of toxic metals (Pb and Cd) were higher than the maximum admissible limits according to the European regulation except for Pb in the reference station. In conclusion, Otala spp. snails in our region can be used as bioindicators of trace element bioavailability and their consumption must be limited to avoid any possible intoxications.