Systematic review of pentachlorophenol occurrence in the environment and in humans in China: Not a negligible health risk due to the re-emergence of schistosomiasis

Pentachlorophenol (PCP) has been widely used for killing snails in areas of China where schistosomiasis is epidemic. With the re-emergence of schistosomiasis, the warranted production and consumption of PCP has inevitably resulted in persistent environmental contamination by it and its impurities, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study aimed to evaluate the contamination status and human burden of PCP and its impurities (PCDD/Fs) in China, considering the previous epidemic and re-emergence of schistosomiasis. We searched studies relevant to PCP occurrence in the environment and in humans in China. Data on snail elimination areas were included to estimate PCP consumption. Relevant publications were analyzed to distinguish PCDD/Fs contamination from PCP usage. PCP contamination was detected ubiquitously in various environmental media and in human samples; environmental levels were generally low, with the exception of some hot spots. In schistosomiasis-epidemic areas, there were significantly higher PCP levels in the environment and in humans than in control areas. Spatial disparities indicated the consistency between serious schistosomiasis epidemic areas and hot spots of PCP contamination. The data suggest an increased trend in PCP contamination of the environment. Specific PCDD/Fs contamination from PCP usage existed even at low environmental levels. The occurrence of PCP in the environment and in humans positively correlated with the epidemic of schistosomiasis. Thyroid-disrupting effects and cancer risk caused by PCP and PCDD/Fs even at low environmental levels in China's schistosomiasis-epidemic areas are of concern.