Assessing Contaminant Uptake and Elimination in Insects: Implications for Sustainable Food Production and Waste Management

Considering the global food crisis and the pressing issue of waste generation, sustainable solutions for food demand are crucial. Insects have emerged as a promising protein source for food and feed due to their efficient bioconversion capacity and ability to utilize nonvaluable products. However, ensuring the safety of insects for food and feed is essential. This study aims to comprehensively evaluate the uptake and elimination of contaminants by insects, going beyond conventional measurements of contamination levels. Methodology: The study employed two-phase bioaccumulation studies involving an uptake phase with a contaminated substrate followed by an elimination phase in a clean substrate. Data from these studies were used in toxicokinetic modelling. The objective was to assess the bioaccumulation capacity of mercury (Hg), cadmium (Cd), lead (Pb), arsenic (As), and various polycyclic aromatic compounds (benzo[a] pyrene [B[a]P], benz[a]anthracene [B[a]A], benzo[b]fluoranthene [B[a] F], and crysene [Cry]) in black soldier fly (BSF) larvae (Hermetia illucens). Although high metal bioaccumulation potential (e.g., for Hg, Cd, Pb, As) in edible insects has already been identified as risk, there is a gap regarding hazard assessment of the organic contaminants (e.g., B[a]P, B[a]A, B[a]F, Cry). The findings indicate that when insects were exposed to the maximum allowed levels of metals according to European Union feed regulations, they accumulated contaminant levels unsuitable for feeding other animals. However, after a depuration period, the insects could reduce the contaminant concentrations to comply with the existing legislation. For instance, a 4 to 5 days depuration period was found sufficient for safer consumption of insects exposed to Hg, while a longer period was required for Cd elimination. Interestingly, no significant accumulation of polycyclic aromatic compounds was observed when insects were fed at the maximum allowed levels. Conclusion: These findings have significant implications, particularly when insects are employed as waste converters, where concerns arise regarding contaminants. This study supports the implementation of a depuration period after exposure to waste that may vary depending on the classes of contaminants involved. Toxicokinetics is an adequate tool for the safety assessment of insects as feed and food, but it also defines the conditions that will assure their sustainable use in waste management.

We acknowledge financial support to CESAM by FCT/MCTES (UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020) through national funds. This study was supported by the ENTOSAFE project (PTDC/CTA-AMB/0730/2021). D. Cardoso was hired under the Scientific Employment Stimulus Individual Call (CEECIND/01190/2018). Patrícia V. Silva was funded by the project NATURAL (Nano clays for removel/capture of phosphates and its reuse as fertilizer CENTRO-01-0247-FEDER-047080) through a pos-doctoral grant (BIPD/UI50/6103/2021).

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