Lead contamination in cassava-based food and tubers (Manihot esculenta Crantz) in French Guiana: evidence for soil-to-plant transfer as the primary source

Loic Alexandre Martin , Sandra Ianez, Michael Rapinski , Yvonette Guillomé, Elvire Lassuka, Marquilène Narcisso, Damien Davy, Guillaume Odonne, Laurence Maurice 

This study investigates lead (Pb) contamination in cassava in French Guiana, focusing on its sources, accumulation processes, and. Previous studies in the area have shown that cassava-based products could be a source of lead in diets, raising concern about human exposure. The results show that cassava tubers often contain lead concentrations and 72% of the analysed samples (n=81) exceed international safety thresholds. However, processing steps such as grating (n=19), pressing (n=9), and cooking (n=30) do not increase lead levels, contrary to previous assumptions. Final products like cassava semolina (couac, n=17) and flatbreads (cassaves, n=13) reflect the median concentrations already present in raw tubers, indicating that contamination mainly originates from soils rather than processing tools and cooking utensils. The study highlights the importance of soil properties in lead uptake by these tubers. Soils rich in fine particles and low in organic matter tend to promote higher lead accumulation in cassava. Additionally, some cassava varieties, particularly yellow ones, appear to accumulate more lead than others. From a health perspective, regular consumption of cassava-based foods may pose risks, especially for children and pregnant women. However, certain products such as cassava starch (n=4) seem to contain very low lead levels and may represent safer dietary options. In conclusion, lead contamination in cassava is primarily environmental in origin and not linked to processing practices. Further research is needed to better understand soil-to-plant transfer mechanisms and to develop strategies that reduce exposure risks for local populations.