Concentrations and congener group profiles of short- and medium-chain chlorinated paraffins in animal feed materials

Chlorinated paraffins (CPs) are ubiquitous environmental pollutants that are lipophilic and can accumulate in the food chain. Animal-derived products are predominant contributors to human CP exposure. CPs in animal feed might accumulate in domestic animals through dietary exposure, leading to potential contamination of animal-derived food products and human health risks. However, information on the presence of CPs in animal feed materials is scarce. In this study, 16 animal feed material samples were collected in China in 2016. Thirteen of the samples were of animal origin and three were of plant origin. The concentrations and carbon and chlorine congener group profiles of shortchain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in these animal feed materials were investigated. The concentrations of SCCPs were higher than those of MCCPs in all of the samples. The SCCP concentration range was 120 to 1700 ng/g (mean 640 ng/g), and the MCCP concentration range was 6.4 to 260 ng/g (mean 78 ng/g). Fish meal had the highest SCCP and MCCP concentrations. The lowest SCCP and MCCP concentrations were detected in peanut meal and whey powder, respectively. The concentrations of SCCPs and MCCPs varied among the types of animal feed materials. SCCP and MCCP concentrations also varied among samples of the same type of animal feed material. Relatively high concentrations of SCCPs and MCCPs were detected in feed materials of animal origin. The predominant congener groups in the animal feed materials were C10-11Cl6-7 for SCCPs and C14Cl7 for MCCPs. The carbon and chlorine congener group profiles of SCCPs indicated that SCCP contamination in the animal feed materials might arise from commercial CP mixtures.