Effects of cooking methods on the residues and bio-accessibility of fipronil and its metabolites in chicken, pork and beef

Fipronil and its metabolite residues in meat are persistent and bio-accumulative, which are properties that pose potential risks to neurological, hepatic, and thyroid functions upon chronic human exposure. This study aimed to systematically evaluate the effects of four cooking methods on the residue levels and bio-accessibility of fipronil and its metabolites in livestock and poultry meat using an established UHPLC-MS/MS) and an <i>in vitro</i> digestion model. The concentrations of fipronil and its metabolites in chicken, pork and beef generally declined with prolonged processing time, with reduction ranges of 9.7%-36.0%, 9.4%-30.1%, 1.3%-34.2%, and 6.0%-37.3% for frying, microwaving, baking, and boiling, respectively. The most significant reductions were observed in the frying and boiling treatment groups (<i>p</i> < 0.05). <i>In vitro</i> simulated digestion experiments were conducted to investigate the bio-accessibility of fipronil and its metabolites, which reflected the actual amount absorbed by the human body. The results showed that bio-accessibility of fipronil and its metabolites was 0-10.0% after <i>in vitro</i> digestion, which was significantly lower in processed than in untreated groups (<i>p</i> < 0.05). This indicated that the fraction absorbed by the human body was limited. The unabsorbed residues re-entered the environment, contaminating soil and water sources, thereby leading to re-accumulation of these compounds in livestock and poultry. Therefore, relying solely on the cooking process cannot fully control the concentrations of residues of fipronil and its metabolites. Addressing such food safety issues still requires strong control measures at the livestock farming source.