Research and control of well water pollution in high esophageal cancer areas.

AIM: In order to detect risk factors for esophageal cancer, a national research program was carried out during the Eighth Five-Year Plan (from 1991 to 1995). METHODS: Cixian County and Chichen County in Hebei Province were selected as the index and the control for the study fields with higher or lower incidence of esophagus cancer in China, respectively. In these areas, we investigated the pollution of three nitrogenous compounds in well water for 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. They were significantly higher than their levels (3.84 mg/L, 0.004 mg/L and 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 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, significantly higher than 186 kg per hectare in Chichen County (t=9.603, P<0.001). CONCLUSION: These investigations indicate that the pollution of nitrogenous compounds in well water for drinking is closely related to the use of nitrogen fertilizer in farming, and there is a significantly positive correlation between the level of three nitrogenous compounds in well water and the mortality of esophageal cancer (correlation coefficient =0.5992). We suggest that improvement of well system for drinking water quality should be an effective measure for esophageal cancer prevention and control in rural areas.

Field population-based blocking treatment of esophageal epithelia dysplasia.

AIM: To confirm the value of blocking treatment by zenshengping (ZSP), a Chinese herb composite, and Riboflavin for esophageal epithelia dysplasia cases screened out in high risk area in northern china by exfoliative balloon cytology (EBC), so to reduce the incidence rate of esophageal cancer(EC). METHODS: Esophageal epithelium dysplasia cases including mind esophageal epithelium dysplasia (MEED), stage one severe esophageal epithelium dysplasia (SEED I), and stage two severe esophageal epithelium dysplasia (SEED II) were screened out from people aged 40 years and older in the high risk area of Chixian. These cases were randomly divided into a treatment and control group. Subjects in the treatment and control groups took ZSP, riboflavin, and placebo daily for three years. EC cases registered by cancer registry and identified by EBC re-screening in the treatment and control groups were used to calculate incidence and blocking rates to demonstrate the effects of blocking medication. RESULTS: It was found that 31.92% and 24.15% of people aged 40 years and older in Cixian could been diagnosed as MEED and SEED cases. The severity of dysplasia increased with age. ZSP had blocked EC occurrence by 47.79% after 3 year medication among the SEED cases. CONCLUSION: ZSP can block the development from SEED I and SEED II to EC by 47.79%. Efforts should be made to screen and treat dysplasia cases in people aged 40 years and older in high risk areas to reduce the mortality figures.