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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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We report results from an evaluation of the levels of heavy metals, i.e., copper (Cu), cadmium (Cd), lead (Pb), nickel (Ni), manganese (Mn), chromium (Cr), and iron (Fe) in sediment and tilapia fish samples from a wide stretch of the Kafue river of Zambia. In sediment samples, the highest Pb and Fe concentrations were recorded at Hippo Dam, i.e., 36.2 ± 0.1 mg/kg dw and 733 ± 37 mg/kg dw at Kafue Town, respectively. Other notably high metal concentrations in sediment were Cr at Kafue Bridge (42.5 ± 0.1 mg/kg dw [dw]), Cu at Mpongwe (233 ± 5 mg/kg dw), and Mn at Kafue Town (133 ± 1 mg/kg dw); it was highest at Ithezi Tezhi Dam at 166 ± 1 mg/kg d. Three fish species, i.e., three-spot bream Tilapia andersonii, red-breasted bream T. rendalli, and nile tilapia Oreochromis niloticus were evaluated for levels of the seven metals. The concentrations of the metals in these fish species afforded estimation of the biota sediment-accumulation factor, which is the ratio of the concentration of the metal in liver to that in the sediment. The coefficients of condition (K) values, which give an indication of the health of the fish, were also estimated. The K values ranged from 2.5 ± 0.5 to 5.1 ± 0.6 in all of the three fish species. Partial least squares analysis showed that heavy metals are generally sequestered evenly in all of the parts of all of the three fish species except for elevated levels of Mn, Cd, and Pb in the liver samples.

A multiple reaction monitoring liquid chromatography – mass spectrometry method for the simultaneous determination of five antiretroviral drugs in human blood plasma.