Edible insects: Understanding benzo(a)pyrene toxicokinetics in yellow mealworms for safe and sustainable consumption

Abstract

The global interest in edible insects as sustainable protein sources raises concerns about the bioaccumulation of contaminants, including polycyclic aromatic hydrocarbons (PAHs), to problematic levels. Understanding the accumulation dynamics of PAHs in edible insects is highly relevant due to the widespread sources and toxicological profiles; however, the bioaccumulative potential of PAHs in edible insects is unexplored. This study examined the uptake and elimination dynamics of benzo(a)pyrene (B(a)P), a representative and carcinogenic PAH, in yellow mealworm larvae (YMW, Tenebrio molitor). Larvae were exposed to feeding substrate with varying B(a)P concentrations (0.03, 0.3, and 3 mg kg^-1), and uptake (21 days in B(a)P-contaminated substrate) and elimination (21 days in B(a)P-free substrate) kinetics were subsequently assessed. The results showed that YMW can eliminate B(a)P, revealing dose-dependent B(a)P bioaccumulation in these insects. Larvae fed on a substrate with 0.03 mg kg^-1 accumulated B(a)P over 21 days, presenting values of 0.049 (Standard deviation - 0.011) mg kg^-1 and a kinetic-based (BAF_kinetic) of 1.93 g _substrate g _organism^-1, exceeding the EU regulatory limits for food. However, with a B(a)P half-life (DT₅₀) of 4.19 days in the larvae, an EU legislation safety criterion was met after a 13-day depuration period in clean substrate. Larvae exposed to substrates with 0.3 and 3 mg kg^-1 showed B(a)P accumulation, with BAF_kinetic values of 3.27 and 2.09 g _substrate g _organism^-1, respectively, not meeting the current legal standards for food consumption at the end of the exposure to B(a)P. Although the B(a)P half-life values after 35 days were 4.30 and 10.22 days (DT_50s), the larvae retained B(a)P levels exceeding permitted food safety limits. These findings highlight a significant oversight in regulating PAHs in animal feed and the need for comprehensive safety evaluations of PAH hazards in edible insects for improved PAH feeding guidelines.

Keywords: Chemical hazard; Depuration; Elimination; Feed safety; Polycyclic aromatic hydrocarbons; Tenebrio molitor; Uptake.