Improving Product Safety for Edible Insects: Toxicokinetics of Hg in Tenebrio molitor and Hermetia illucens

Abstract

Sustainability, circularity, and Zero Waste policies are timely concepts for policy development and strategies in the European Union (EU) and other global regions. Insects can likely become key players in the bioconversion of waste to valuable material and promise one solution to achieve diverse societal goals. Insects further present strategic opportunities as food products; however, it is necessary to understand how insects accumulate and eliminate priority contaminants from different substrates where they can be reared. In the present study, we expanded beyond previous work with mercury (Hg) to examine bioaccumulation kinetics in Tenebrio molitor (YMW) and Hermetia illucens (BSF). Two-phase bioaccumulation assays, with an uptake (contaminated Hg substrate) and elimination phase (clean substrate), followed by toxicokinetic modeling, showed that both insects have a high capacity to regulate Hg, often reaching an internal steady-state concentration at level responding on the substrate concentration of Hg. Of importance for product safety, both insects quickly eliminated Hg after being transferred to clean substrate. Specifically, BSF eliminated half of the accumulated Hg in approximately 1 day (after 5 days of Hg exposure) and YMW in 4–5 days (after 21 days of Hg exposure). These results provide crucial product safety information for insect producers using possibly contaminated substrates, specifically informing the amount of time for Hg depuration prior to processing and commercialization for food and feed.