Bioavailability of insect growth regulators in citrus and stone fruits

The aim of this study was to offer data about the bioavailability of flufenoxuron, lufenuron, pyriproxyfen and fenoxycarb in common commodities like mandarin, apricot and peach. The in vitro bioavailability of the compounds was studied not only in fresh fruit but also in standards and canned food in order to establish possible differences according to the matrix. The gastric digestion was simulated with porcine pepsin at pH 2, for 2 h in a shaking water bath at 37 degrees C. The intestinal digestion was simulated with porcine pancreatin at pH 7, for 2 h in a shaking water bath at 37 degrees C. The intestinal absorption was simulated with cellulose dialysis tubing filled with a solution of sodium carbonate. No in vitro bioavailability was observed in mandarin, peach and apricot samples spiked at the concentrations generally found in the market for the raw and processed commodities. In standards, the dialysis started at the level of 0.25 mg/kg. This is an approximation to the pesticide digestion and absorption in humans.