Transfer and bioaccumulation of endogenous arsenic, cadmium, and lead from practical rearing substrates to farmed insects

This study assessed the transfer of cadmium (Cd), arsenic (As), and lead (Pb) in five farmed insect species from 27 non-spiked practical feed substrates. The insect species, black soldier fly ( Hermetia illucens ), yellow mealworm ( Tenebrio molitor ), lesser mealworm ( Alphitobius diaperinus ), house cricket ( Acheta domesticus ), and migratory locust ( Locusta migratoria ), and substrates were sampled both from in-house laboratory experiments and from commercial/large-scale producers in Europe. Trace element contents were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Bioaccumulation was defined when dry weight element concentrations in insects exceeded those in the substrate. Bioaccumulation of As and Pb was not observed in any insects in this study, while bioaccumulation of Cd in H. illucens and T. molitor were confirmed. All insect samples remained under maximum allowable Cd, As, and Pb levels for animal feed ingredients in the EU. Compliance with EU novel food safety regulations for specific insect products was more mixed. A. diaperinus and A. domesticus were in all cases compliant, L. migratoria compliance for Pb and Cd was substrate-dependent, and one T. molitor sample was slightly above the published Cd limit. With regard to Pb in T. molitor , all samples tested were below the experimentally determined LOD of this study (0.07 mg Pb/kg DM; 0.02 mg/kg WM); however, the current limits for frozen T. molitor larvae (0.01 mg Pb/kg as is ) and UV-treated T. molitor powder (0.02 mg Pb/kg as is ) are also below the LOD of this study and thus are likely difficult to obtain. By monitoring endogenous Cd, As, and Pb contents from multiple insect species, substrates, and production sites, this study provides realistic data on the safety of farmed insects. • Sampled five production insect species and 27 practical rearing substrates • Analyzed endogenous arsenic, cadmium, and lead contents using ICP-MS • Bioaccumulation of Cd in H. illucens, T. molitor confirmed in production settings • Levels of As, Cd, and Pb in insects were below EU limits for animal feed • EU novel foods limits for some T. molitor products were below the LOQ of this study