Water is an important pathway for human exposure to heavy metals. Accurate assessment of the health risks that are related to exposure to heavy metals in drinking and household water are required for the preparation of targeted health risk prevention measures. This study explores and identifies the health risks related to exposure to heavy metals via drinking and household water pathways in Xigu District, Lanzhou, northwestern China, using household water samples and survey data obtained during July-September 2015 (wet season) and December 2015-January 2016 (dry season). During each period, drinking water and household water that were available for use by children aged 0-5 and 6-17 years were sampled and a questionnaire on water-related behavior patterns was completed for each household. Cd, Cr, Pb, and As concentrations were analyzed in all water samples, and were used along with water-related exposure factors from the questionnaires to estimate exposure doses and associated health risks using models recommended by the United States Environmental Protection Agency (US EPA). The results showed that the concentrations of Cd, Cr, Pb, and As in both drinking and household water samples did not exceed the relative thresholds defined in China's national water quality standards. The concentrations of heavy metals in household water were more affected by seasonal factors than of those of drinking water. The non-cancer and cancer risks were in the ranges of 2.82×10-8-2.43×10-2 and 7.55×10-9-3.62×10-5, respectively, which are within acceptable levels, although the non-cancer and cancer risks from drinking water were both higher than of those determined for household water. Furthermore, the non-cancer and cancer risks from household water for children aged 0-5 years were lower than of those for children aged 6-17 years in each period. However, the cancer risk from drinking water for children aged 0-5 years was lower than of that for children aged 6-17 years, whereas the reverse was found for non-cancer risks. This study indicates that Cd, Cr, Pb, and As in drinking and household water did not pose significant detrimental effects to human health, and that the refined exposure assessment used could reduce uncertainties in health risk assessments.
Keywords: children; drinking water; health risk; heavy metal; household water.