ASSESSMENT OF THE BIOACCESSIBILITY OF ORGANOCHLORINE PESTICIDES USING A CHICKEN GASTROINTESTINAL TRACT MODEL

Abstract

In 2023, a large-scale inventory under the FAO GCP/SEC/011/GFF project identified approximately 1.3 thousand tons of obsolete persistent organic pollutants (POPs) in Kazakhstan. Studies conducted from 2013 to 2024 at former pesticide warehouses in the Almaty region revealed concentrations significantly exceeding maximum allowable concentrations (MAC) by more than 10 times. Due to their lipophilicity and persistence, these compounds pose a severe risk of transfer into livestock and poultry, which may ingest up to 30 g of soil daily. The analyzed soil featured a pH of 8.0, 27.9% ash content, and 3.4% organic matter, with organochlorine pesticide (OCP) concentrations ranging from 4.5 to 5.0 µg/g. Bioaccessibility of OCPs under simulated gastrointestinal conditions increased significantly from gastric to intestinal phases and was markedly enhanced by the inclusion of Tenax as a sorption sink, rising from 0.01–17.10% to 24.00–52.70%. Overall, mean bioaccessibility ranged from 25% to 67%, with the highest values observed for 4,4-DDT and β-HCH. These findings highlight the critical role of sorption sinks in improving the physiological relevance of in vitro models by better simulating absorption processes, thereby providing more accurate estimations of bioavailable contaminant fractions for food safety and public health.