Évaluation de bioaccumulation des métaux toxiques (pb, cu, mn) dans les espèces de crabes Callinectes amnicola et Cardisoma armatum consommés avec les légumes d’Abelmoschus esculentus dans la basse vallée de l’Ouémé (Benin, Afrique de l’ouest)

Abstract

Objective : to evaluate the bioaccumulation of toxic metals (Pb, Cu, Mn) for two different species of crabs (i.e., Callinectes amnicola and Cardisoma armatum) and of vegetable Abelmoschus esculentus (family Malvaceae) commonly called Okra and consumed in the lower valley of the Ouémé. Methodology and results:To do this, the contents of three metallic trace elements (MTE) manganese (Mn), copper (Cu) and lead (Pb) were sought in water, sand sediment, vegetables and crabs by using a flame atomic absorption spectrophotometer in 12 water and sediment samples and then in 72 crab samples. To search for lead, manganese and copper, an assessment of the health risks associated with the consumption of these contaminated products was carried out using a simplified standard approach. The results showed that all the Abelmoschus esculentus vegetables had Mn and Cu contents exceeding the WHO regulations. The results also revealed higher Mn concentrations in the sediment compared to the other two crab samples. Cardisoma armatum crabs accumulate more Cu and Pb than the Callinectes amnicola crab. The concentrations of lead (Pb) and Mn were below the standards set by the WHO. On the other hand, those of copper and manganese largely exceeded the regulations. The bioconcentration factor (BCF) varied from 0.25 to 0.29 for Mn, from 0.15 to 0.17 for Cu and from 0.67 to 0.82 for Pb. The presence of these metallic trace elements in crabs, can only result from the phenomenon of bioavailability in sediments. Conclusion and application of results: In conclusion, it can be remembered that the assessment of the bioaccumulation of toxic metals in food has shown that the consumption of crabs and vegetables constitutes a public health hazard for the population of the lower valley of the Ouémé. It would be essential to attract the attention of the populations so that they adopt a varied food ration. These results should be used as a decision-making tool for health authorities. The main recommendation resulting from the results is to carry out health surveillance in the lower valley of the Ouémé with regard to food.