A correlation study between mean nitrate nitrogen levels (ppm) in drinking water samples (
N=1389) of Chilean urban areas and age-adjusted death rates per 100000 population from stomach cancer, by province or region and sex, was made.
Drinking water samples from all provinces (N=25) had a weighed mean of 1.446 ppm (S.E.M. 0.068) with a range of 0.00–30.00 ppm.
Nitrate nitrogen levels showed a positive but not significant association with male death rates. The correlation coefficient was +0.0335. Similarly, such levels did exhibit a positive but not significant correlation with female death rates (r=+0.0486). When NO3-N levels and male (r=+0.1367) or female (r=+0.1143) death rates were studied, by region, positive but insignificant correlations were detected. Using Cochran's approximation, mean nitrate nitrogen levels in drinking water samples from six provinces with 50% of the Chilean population (period 1953–55 versus 1973–75), showed a decrease from 1.835 to 1.291 ppm, but there was no significant difference (t=1.32) between the two values, except in samples from Santiago Province (t=2.11, P<0.05). provinces="" (south="" central="" area)="" showing="" the="" highest="" gastric="" cancer="" mortality="" rates="" in="" the="" world="" for="" females="" (up="" to="" 40.8/100,000),="" and="" ranking="" second="" for="" males="" (up="" to="" 84.1/100,000),="" exhibited="" a="" very="" low="" mean="" level="" (0.825="">
Key words Stomach cancer - High-risk population - Nitrate nitrogen levels - Drinking water - Urban areas - Soil pH