[Trihalomethane and haloacetic acid concentrations in drinking water and their estimated intake during pregnancy in the INMA cohort (Guipúzcoa, Spain)].

OBJECTIVES To report trihalomethane (THM) and haloacetic acid (HAA) concentrations in drinking water, assess variations in these concentrations depending on source and over time, and estimate individual intake during pregnancy. METHODS Water taken from 33 representative points of the water supply network of the 25 municipalities in the study area was analyzed from 2006-2008. Water drinking habits were recorded using a questionnaire. RESULTS Mean total THM concentrations were 16.9 μg/L (standard deviation, 7.9), while the mean value for the sum of concentrations of five HAA (monochloroacetic, dichloroacetic, tricholoroacetic, monobromoacetic, and dicromoacetic acids) was 10.9 μg/L (standard deviation, 4.9). Concentrations were lower in spring waters, which were only chlorinated, compared with dam waters, which were subject to a complete purification treatment: 8.8 μg/L vs 19.1 μg/L (p<0.01) and 8.2 μg/L vs 11.7 μg/L (p<0.01). Concentrations significantly increased with the number of deposits in the network and with their rechlorination and were higher in the summer and fall. Mean intakes of total THM and of the five HAA were lower in women supplied with spring water. Intakes differed depending on supply reservoir. CONCLUSIONS Disinfection by-products in water are affected by water source, supply network structure, and annual season. The mean intake of these products varies depending on the source of drinking water. Mean intakes of all products were much lower than values recommended by the World Health Organization.