Is nitrate in the drinking water associated with the risk of cancer in the urban UK?

Several studies have suggested that nitrate levels in drinking water may be linked with stomach cancer. Recent investigations of this hypothesis in rural areas of the UK, where nitrate levels can be high, have been inconclusive. The present study examined mortality data for the years 1969-1973 in 253 urban areas in relation to treated water nitrate levels. Variations in socioeconomic status and urban area size were taken into account. Drinking water nitrate levels were negatively associated with mortality from stomach cancer even when the analysis was restricted to urban areas with nitrate levels above the EEC guide. There was no evidence of a positive association between nitrate in the drinking water and the risk of stomach cancer in the urban areas of the UK, an important finding for the British water industry.