Drinking water, diet, indoor air: Comparison of the contribution to environmental micropollutants exposure

This study collated 254,441 analytical results from drinking water quality monitoring in order to compare levels of exposure of the French adult population from drinking water with that from total diet for 37 pesticides, 11 mineral elements, 11 polycyclic aromatic hydrocarbons (PAH), 6 non dioxin-like polychlorobiphenyls (NDL PCB), 5 ether polybromodiphenyl ethers (BDE), 2 perfluorinated compounds. It also compares levels of exposure from drinking water with that from inhalation of indoor air for 9 volatile organic compounds (VOC) and 3 phthalates. The vast majority of the water analysis results showed values below the limits of quantification and this comparison was primarily made on the basis of a highly pessimistic scenario consisting in considering the data below the limits of quantification as being equal to the limits of quantification. With this conservative scenario, it can be seen that tap water makes a minor but potentially non-negligible contribution for a few micropollutants, by comparison with diet and air. It also shows that exposure through drinking water remains below the toxicity reference values for these substances. Apart from a few extreme values reflecting exceptional local situations, the concentrations measured for the minority of positive samples (below the 95th percentile value) suggest a very low risk for human health. Lower limits of quantification would however be of use in better estimating the safety margin with regard to the toxicity reference values, in particular for BDE, PAH and NDL PCB.