Dietary Lead Exposure in Mealworm Larvae (Tenebrio molitor) and Its Implications for the Safety of Edible Insects

This study examined the toxicological, and bioaccumulative effects of dietary lead (Pb) on Tenebrio molitor larvae, increasingly considered for human and animal consumption within sustainable food and feed production systems. Larvae were exposed for 21 days to an oat-based diet contaminated with lead salts (125–2000 mg Pb/kg). Body mass, and Pb accumulation in the intestine, internal tissues, and cuticle were analyzed. Pb concentrations in larval compartments increased with increasing nominal Pb levels in feed, with concentrations in internal tissues and cuticle reaching 5–6 times higher than in the control. Estimated bioaccumulation factors (BAF) were below 1 in all cases, indicating no biomagnification. Despite high exposure levels, no significant effects on larval survival or biomass gain were observed. These findings indicate that growth-related parameters are not sensitive indicators of Pb exposure. At the same time, substantial Pb accumulation occurred, particularly in the gut and cuticle, highlighting a risk of “hidden” contamination in insect-based production systems. The results emphasize the need for substrate monitoring and the inclusion of sensitive chemical indicators in food safety risk assessment.