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Many studies have investigated the contamination level, spatial distribution, sources, chiral signals, and potential ecological and public health risks of dichlorodiphenyltrichloroethanes, its metabolites and the isomers of hexachlorocyclohexane in the environment. This study presents a critical review to provide updated knowledge about the fate, persistence, long-range transport and toxicity effects of dichlorodiphenyltrichloroethanes and hexachlorocyclohexanes in the environment on the basis of analytical data between 1990 and 2014. Highest levels were found for dichlorodiphenyltrichloroethanes (200-9300 ng/ L) and hexachlorocyclohexanes (20-36,000 ng/L) with mean values of 1000 and 5600 ng/L, which were 10 and 56 times higher than the European Community allowable residual limit of 100 ng/L, respectively, in Lake Taihu water of China obtained between 1999 and 2000. Levels of dichlorodiphenyltrichloroethanes in sediments and fish species were remarkably higher than hexachlorocyclohexanes. The highest levels of dichlorodiphenyltrichloroethanes in sediments were found up to 780-227,000 ng/g near a production factory in China and 20,000-5,463,000 ng/g in cattle dips disposal areas in Australia. Out of 32 selected locations for common fish species, tilapia had the highest mean concentration of dichlorodiphenyltrichloroethanes up to 3800 ng/g in Noha River of Japan in 2006. Dichlorodiphenyltrichloroethanes and hexachlorocyclohexanes derive from agricultural runoff, industrial and urban wastewater, etc., that ultimately associate with soil and sediments. The carbon-carbon and carbon-chlorine bonds in dichlorodiphenyltrichloroethanes and hexachlorocyclohexanes provide them persistence, lipophilicity and high binding affinity leading to bioaccumulation in the receptor protein. High accumulation of dichlorodiphenyltrichloroethanes and hexachlorocyclohexanes causes mutagenic, carcinogenic and endocrine disrupting toxicity effects to the humans and wildlife.

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