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.