| ObjectiveTo investigate the level and distribution characteristics of 5 selenium speciation,2 chromium speciation,and 2 mercury speciation in drinking water of 14 cities in key river basins and lakes of China,and conduct health risk assessment of people over 18 years of age exposed to different speciation of selenium,chromium,and mercury in monitored cities.In order to provide basis for selenium,chromium,mercury pollution control and limit revision.Methods84 water samples of raw water,finished water and tap water were collected from 28 municipal water plants which were selected as monitoring points in 14 cities of nine key river basins and one key lake(Chaohu)from November to December 2020.The speciation and concentration of selenium and chromium were determined by high performance liquid chromatography inductively coupled plasma mass spectrometry(HPLC-ICP-MS)while the speciation and concentration of mercury were determined by purge and trap/gas chromatography cold atomic fluorescence spectrometry(P&T/GC-CAFS).The selenium,chromium,mercury form contents in different water sample types and different water source types were analyzed by Kruskal-Wallis H test and Mann-Whitney U test.Finally,the health risks of adults of different age groups and genders through oral and transdermal route exposed to different speciation of selenium,chromium,and mercury were evaluated based on the adult exposure parameters obtained in the previous survey in the monitoring city and laboratory tap water test results and the U.S.Environmental Protection Agency exposure model.Results(1)Form concentration test resultsIn the drinking water of 14 cities in this study,three organic selenium speciation were not detected,the Median(minimum,maximum)of Se(?),Se(?),total inorganic selenium,and the total amount of the five selenium forms were 0.03(0.03,0.39),0.18(0.03,0.58),0.23(0.06,0.79)and 0.45(0.34,1.01)?g/L;The median(minimum,maximum)of Cr(?)and Cr(?)were 0.08(0.08,0.79)and 0.07(0.07,0.23)?g/L,respectively;none of the two organic mercury species were detected.The concentration of Se(?)in raw water was higher than that of finished water and tap water(P<0.05),while there was no statistical difference in the concentration levels of the other target substances in the three types of water samples.The concentrations of Se(?),Se(?),the total inorganic selenium and the total amount of the five selenium forms in surface water were higher than those of groundwater(P<0.05),while there was no statistically significant difference in the concentration levels of Cr(?)and Cr(?)in surface water and groundwater.(2)Health risk assessment resultsIn this study,the risk value of oral exposure to different speciation of selenium,chromium,and mercury in 14 cities over the age of 18 accounted for more than 99%of the total risk value of oral and transdermal route,indicating that oral intake was the main way for the human body to be exposed to these pollutants in drinking water.The carcinogenic risk of Cr(?)by oral route was 9.59×10-7,9.12×10-7,9.58×10-7,9.26×10-7,9.19×10-7,8.89×10-7 for people aged 18?24,25?34,35?44,45?55 and over 65,9.56×10-7 and 1.00×10-6 for males and females,respectively.The carcinogenic risk of transdermal route was much lower than 1×10-6 in people of different ages and genders.The non-carcinogenic risk of the two exposure routes of people over 18 years of age exposed to different speciation of selenium,chromium,and mercury was less than 1,among them,the non-carcinogenic risk of selenium generated by oral route accounted for more than 80%of the total non-carcinogenic risk value caused by different forms of pollutantswhile in the transdermal route accounted for more than 67%of the total non-carcinogenic risk value,indicating that selenium was the main non-carcinogenic risk substance.The total carcinogenic risk and total non-carcinogenic risk of the research substances calculated through oral and transdermal route based on the adult exposure parameters of 14 cities were 9.87×10-7 and 3.17×10-3,respectively,the total carcinogenic risk and total non-carcinogenic risk based on the exposure parameters of the American population were 9.55×10-7 and 3.10×10-3,indicating that calculating the risk value based on US exposure parameters would underestimate the actual results.Conclusion(1)The concentration of different forms of selenium,chromium,and mercury in this study did not exceed the limits of Standards for drinking water,indicating that the pollution levels of the three elements in drinking water in 14 cities were low,the water quality was good.Se(?)and Se(?)were the main forms of selenium in drinking water,there were certain levels of Cr(?)and Cr(?)in the water while no detection of organic mercury.(2)In this study,the carcinogenic and non-carcinogenic risks of people over 18 years of age exposed to different speciation of selenium,chromium,and mercury in drinking water in the 14 cities were within negligible risk levels,but the carcinogenic risk of Cr(VI)was close to the negligible risk value,and it is still necessary to strengthen the carcinogenicity of drinking water concentration monitoring of Cr(?). |
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