Translocation, metabolism and distribution of multi-pesticides in rats

The use of pesticides has led to their widespread presence in food, making it unavoidable for the public to be exposed to pesticides through diet. However, few studies have focused on the in vivo distribution of pesticides after exposure. This study comprehensively investigated the residual behavior of nine pesticides and their five metabolites in rats after oral exposure and elucidated the relationship between their physicochemical properties and tissue-specific distribution. During the initial exposure, all tested pesticides and metabolites were detected in the serum and different tissues, with the highest concentration of 3294.03 μg/kg observed in the liver. However, after 48 h of exposure, a majority of the pesticides were undetectable. Correlation analysis revealed a strong negative correlation between pesticide residues detected in the serum, brain, heart, liver, lung, kidney, spleen, and urine as well as physicochemical properties such as molecular weight (Mw) and octanol-water partition coefficient (log Kow). Conversely, a positive correlation was observed between the residues and aqueous solubility (As). Pesticides with lower Mw and log Kow and higher As, such as acetamiprid, imidacloprid, and thiamethoxam, showed higher solubility in serum and higher residual deposition across different tissues. Water-soluble pesticides, such as acetamiprid, imidacloprid, and thiamethoxam, were predominantly excreted through urine, thereby achieving relatively rapid systemic clearance. However, fat-soluble pesticides, such as azoxystrobin, chlorantraniliprole, and pyraclostrobin, were primarily eliminated through the fecal route, which is a comparatively slow process. This study helps in understanding the residual behavior of pesticides in mammals, thereby providing valuable insights for pesticide safety evaluation.