Concentrations and correlations of disinfection by-products in municipal drinking water from an exposure assessment perspective.

Although disinfection by-products (DBPs) occur in complex mixtures, studies evaluating health risks have been focused in few chemicals. In the framework of an epidemiological study on cancer in 11 Spanish provinces, we describe the concentration of four trihalomethanes (THMs), nine haloacetic acids (HAA), 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), four haloacetonitries, two haloketones, chloropicrin and chloral hydrate and estimate correlations. A total of 233 tap water samples were collected in 2010. Principal component analyses were conducted to reduce dimensionality of DBPs. Overall median (range) level of THMs and HAAs was 26.4 (0.8-98.1) and 26.4 (0.9-86.9) µg/l, respectively (N=217). MX analysed in a subset (N=36) showed a median (range) concentration of 16.7 (0.8-54.1)ng/l. Haloacetonitries, haloketones, chloropicrin and chloral hydrate were analysed in a subset (N=16), showing levels from unquantifiable (<1 µg/l) to 5.5 µg/l (dibromoacetonitrile). Spearman rank correlation coefficients between DBPs varied between species and across areas, being highest between dibromochloromethane and dibromochloroacetic acid (r(s)=0.87). Principal component analyses of 13 DBPs (4 THMs, 9 HAAs) led 3 components explaining more than 80% of variance. In conclusion, THMs and HAAs have limited value as predictors of other DBPs on a generalised basis. Principal component analysis provides a complementary tool to address the complex nature of the mixture.

Nitrate and trace elements in municipal and bottled water in Spain.

OBJECTIVES: To describe levels of nitrate and trace elements in drinking water from the study areas of a multicase-control study of cancer in Spain (MCC-Spain). METHODS: A total of 227 tap water samples were randomly collected from 67 municipalities in 11 provinces and the nine most frequently consumed bottled water brands were sampled to measure levels of nitrate, arsenic, nickel, chromium, cadmium, lead, selenium and zinc. RESULTS: The median nitrate level was 4.2mg/l (range<1-29.0), with similar levels in rural and urban municipalities (p=0.86). Trace elements were unquantifiable in 94% of tap water samples. Differences between areas were significant for nitrate (p<0.001) and arsenic (p=0.03). Only nitrate was quantifiable in bottled water (range 2.3-15.6mg/l). CONCLUSIONS: Nitrate levels in municipal water differed between regions and were below the regulatory limit in all samples, including bottled water. Trace element levels were low and mainly unquantifiable in tap and bottled water.