Analysis of heavy metals in drinking water of rural schools in Shaanxi Province / 中国学校卫生

ABSTRACT

Objective@#To understand the status and trend of heavy metal indicators of drinking water in rural schools in different regions of Shaanxi Province, so as to provide scientific basis for safety of drinking water in rural schools.@*Methods@#In 2017-2019, 697 rural school water supply projects in Shaanxi Province were tested for heavy metal indicators in the peripheral water. According to the sanitary standard for drinking water (GB 5749—2006), five heavy metal indicators, including arsenic, cadmium, hexavalent chromium, lead and mercury, were analyzed and evaluated in different years and regions.@*Results@#A total of 2 298 valid water samples were collected and analyzed in 3 years. Except that lead and mercury are all up to standard, the standard rates of other heavy metals such as arsenic, cadmium and hexavalent chromium were 98.83%, 99.91% and 96.95% respectively. Compared with the Northern Shaanxi plateau and Qinba mountain area, the standard rate of water arsenic in Guanzhong Plain was lower (χ2=5.67, 13.59,P<0.01). The standard rate of hexavalent chromium was the highest in Qinba mountain area, followed by Guanzhong Plain, and the lowest in Northern Shaanxi plateau (χ2=20.48, 17.05, 48.32, P<0.01). Two samples of cadmium exceeding standard were from the Northern Shaanxi plateau.@*Conclusion@#The heavy metal index of drinking water in rural schools in Shaanxi Province exceeds the standard, which has obvious regional characteristics. We should focus on the harm of arsenic, hexavalent chromium and other heavy metals to the health of students in the Northern Shaanxi plateau and Guanzhong Plain. Cadmium and mercury in drinking water in local areas should be paid continued attention. Safety of drinking water in schools should be ensured from the aspects of water source selection and water treatment technology.