Effects of acrylamide on indoor air based on the reactions with O3 and •OH: Mechanism, kinetics, and toxicity evaluation

Abstract

Acrylamide (AM), a hazardous chemical prevalent in daily food processing, exerts carcinogenic, teratogenic and mutagenic impacts. In the ambient environment, O3 and •OH stand as pervasive oxidants. However, the reaction mechanism of AM with atmospheric oxidants O3 and •OH is still unclear. This study delves into the oxidation behavior of AM with O3/•OH in both gas phase and aqueous droplets, unveiling their environmental implications through theoretical calculations. The intricate reaction mechanisms and rate constants (k) governing the interplay of AM with O3 and •OH are clarified. Notably, the energy barrier of AM reaction with O3 surpasses that of AM with •OH. Impressively, the gas phase k values of the two systems (kO3+AM = 3.52 × 10−16 cm3 molecule−1 s−1, k•OH+AM = 6.64 × 10−12 cm3 molecule−1 s−1) are 2–3 times higher than those observed in aqueous reactions. An increase in temperature enhances the reaction rate constant between O3 and AM, but decreases that of •OH with AM. In the field of reaction kinetics, the half-lives of AM degradation initiated by O3 and •OH are 0.55 h and 1.16 h in the gas phase, and 1.56 h and 2.04 h in aqueous droplets. The presence of aqueous droplets may exhibit the transformation potential of AM, which is more likely to accumulate in dry food processing. Furthermore, resultant products typically exhibit reduced toxicity compared to AM. However, in this target reaction, the formation of organic acids, glycolaldehyde, 2-oxoacetamide and multi-functional compounds assumes significance, serving as vital precursors of indoor secondary organic aerosol.