We conducted a population-based case-control study of
adenocarcinoma of the stomach and esophagus in
Nebraska, U.S.A. Nitrate concentrations in public
drinking water supplies were linked to residential water
source histories. Among those using private wells at the
time of the interview, we measured nitrate levels in
water samples from wells. Dietary nitrate and nitrite
were estimated from a food-frequency questionnaire.
Among those who primarily used public water supplies
(79 distal stomach, 84 esophagus, 321 controls), average
nitrate levels were not associated with risk (highest
versus lowest quartile: stomach OR=1.2, 95% CI [0.5–
2.7]; esophagus OR=1.3, 95% CI [0.6–3.1]). We
observed the highest ORs for distal stomach cancer
among those with higher water nitrate ingestion and
higher intake of processed meat compared with low
intakes of both; however, the test for positive interaction
was not significant (p=0.213). We did not observe
this pattern for esophagus cancer. Increasing intake of
nitrate and nitrite from animal sources was associated
with elevated ORs for stomach cancer and with a significant
positive trend in risk of esophagus cancer (Ptrend=
0.325 and 0.015, respectively). Larger studies
with higher exposures to drinking water sources of
nitrate are warranted to further evaluate N-nitroso
compound precursors as risk factors for these cancers.