Factors Affecting the Bioaccessibility and Intestinal Transport of Difenoconazole, Hexaconazole, and Spirodiclofen in Human Caco-2 Cells Following in Vitro Digestion.

This study examined how gastrointestinal conditions affect pesticide bioaccessibility and intestinal transepithelial transport of pesticides (difenoconazole, hexaconazole, and spirodiclofen) in humans. We used an in vitro model combining human gastric and intestinal digestion, followed with Caco-2 cell model for human intestinal absorption. Bioaccessibility of three tested pesticides ranged from 25.2 to 76.3% and 10.6 to 79.63% in the gastric and intestinal phases, respectively. A marked trend similar to the normal distribution was observed between bioaccessibility and pH, with highest values observed at pH 2.12 in gastric juice. No significant differences were observed with increasing digestion time; however, a significant negative correlation was observed with the solid-liquid (S/L) ratio, following a logarithmic equation. R2 ranged from 0.9198 to 0.9848 and 0.9526 to 0.9951 in the simulated gastric and intestinal juices, respectively, suggesting that the S/L ratio is also a major factor affecting bioaccessibility. Moreover, significant dose- and time-response effects were subsequently observed for intestinal membrane permeability of difenoconazole, but not for hexaconazole or spirodiclofen. This is the first study to demonstrate the uptake of pesticides by human intestinal cells, aiding quantification of the likely effects on human health and highlighting the importance of considering bioaccessibility in studies of dietary exposure to pesticide residues.

In-vitro bioaccessibility of five pyrethroids after human ingestion and the corresponding gastrointestinal digestion parameters: A contribution for human exposure assessments.

Bioaccessibility is a crucial parameter in assessing the absorption of contaminants during the human digestive process, but few studies have involved the differences in the bioaccessibilities of pesticides. To investigate the mode of using the in vitro bioaccessibility to refine estimates of dietary exposure to pesticide residues, this study measured the bioaccessibilities of five pyrethroids in apples, and then, it modelled physicochemical predictors (gastrointestinal pH, digestive times, and the solid-liquid (S/L) ratio) of the bioaccessibilities of pyrethroids. Apple samples of gastric and intestinal phase digestive juices were obtained from an in vitro simulated digestion model. Our survey of in vitro digestion models found that the bioaccessibilities ranged from 4.42% to 31.22% and 10.58%-35.63% in the gastric and intestinal phases, respectively. A sharp trend similar to a normal distribution was observed between the bioaccessibilities and pH values. The bioaccessibility reached its highest value at a pH of 1.91 in the simulated gastric juice and did not significantly change with an increase of the digestive time. A significant negative correlation occurred between the bioaccessibility and S/L ratio, which followed a logarithmic equation. The correlation coefficients (R2) ranged from 0.9259 to 0.9831 and 0.9077 to 0.9960 in the simulated gastric and intestinal juice, respectively, suggested that both the pH value and S/L ratio were the main factors affecting the bioaccessibility. Furthermore, a combination of the acceptable daily intake (ADI) and bioaccessibility for human exposure assessments indicated the implication that traditional risk assessment using ADI may seriously overestimate the actual risk.