Enantioselective characteristics, bioaccumulation and toxicological effects of chlordane-related compounds in laying hens

Chlordane-related compounds are ubiquitously detected in the environment and can transfer and accumulate to animals through food chain to cause adverse effects . In this study, the dynamic distribution and the enantiomeric profile of chlordane-related compounds in laying hens over time were investigated. The effect of these compounds on immune-associated cells in the intestinal tract and histopathology in some tissues were also evaluated after long-term exposure. The chlordane-related compounds preferentially accumulated in fat, followed by the intestines, ovum, and egg yolk during long-term exposure. The metabolites heptachlor epoxide and oxychlordane were mainly formed in the liver of hens by epoxidation or hydroxylation . The high accumulation ratios of trans -nonachlor and MC5 were found in ovum and egg yolk after long-term exposure, implying a greater risk to the hens’ offspring. Chlordane-related compounds may cause abnormal lipometabolism and glycometabolism in liver of hens. Additionally, (−)-Cis-chlordane was dominant in all tissues of laying hens and its dominance increased over time. Conversely, (+)-isomer of metabolite oxychlordane was overwhelmingly dominant during the experiment. These findings about enantioselectivity , metabolic processes and toxicological effects are crucial in understanding the exposure risk of chlordane-related compounds.