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AIM:In order to detect risk factors for esophageal cancer,a national research program was carried out during the EighthFive-Year Plan (from 1991 to 1995).METHODS:Cixian County and Chichen County in HebeiProvince were selected as the index and the control for thestudy fields with higher or lower incidence of esophaguscancer in China,respectively.In these areas,we investigatedthe pollution of three nitrogenous compounds in well waterfor drinking and the use of nitrogen fertilizer in farming.RESULTS:In well water,nitrate nitrogen,nitrite nitrogenand ammonia nitrogen were 8.77 mg/L,0.014 mg/L and0.009 mg/L in Cixian County in 1993,respectively.They weresignificantly higher than their levels (3.84 mg/L,0.004 mg/Land 0.004 mg/L) in Chichen County (P<0.01,t=6.281,t=3.784,t=3.775).There was a trend that the nitrogenouscompounds in well water increased from 1993 to 1996.The amount of nitrogen fertilizer used in farming was 787.6 kg per hectare land in Cixian County in 1991,significantlyhigher than 186 kg per hectare in Chichen County (t=9.603,p<0.001).CONCLUSION:These investigations indicate that the pollutionof nitrogenous compounds in well water for drinking is closelyrelated to the use of nitrogen fertilizer in farming,and there isa significantly positive correlation between the level of threenitrogenous compounds in well water and the mortality ofesophageal cancer (correlation coefficient=0.5992).We suggestthat improvement of well system for drinking water qualityshould be an effective measure for esophageal cancerprevention and control in rural areas.
AIM: In order to detect risk factors for esophageal cancer, a national research program was carried out during the Eighth Full-Year Plan (from 1991 to 1995) .METHODS: Cixian County and Chichen County in Hebei Province were selected as the index and the control for thestudy fields with higher or lower incidence of esophaguscancer in China, respectively.In these areas, we investigated the pollution of three nitrogenous compounds in well waterfor drinking and the use of nitrogen fertilizer in farming .RESULTS: In well water, nitrate nitrogen, nitrite nitrogen and ammonia nitrogen were 8.77 mg / L, 0.014 mg / L and 0.009 mg / L in Cixian County in 1993, respectively. The we weignificantly higher than their levels (3.84 mg / L, 0.004 mg / Land 0.004 mg / L) T = 3.784, t = 3.775). There was a trend that the nitrogenous compounds in well water increased from 1993 to 1996. The amount of nitrogen fertilizer used in farming was 787.6 kg per hectare land in Cixian County in 1991, significantlyhigher t han 186 kg per hectare in Chichen County (t = 9.603, p <0.001) .CONCLUSION: These investigations of that pollution of nitrogenous compounds in well water for drinking is closely linked to the use of nitrogen fertilizer in farming, and there isa significant positive correlation between the level of threenitrogenous compounds in well water and the mortality of esophageal cancer (correlation coefficient = 0.5992) .We suggestthat improvement of well system for drinking water qualityshould be an effective measure for esophageal cancerprevention and control in rural areas.