Environmental Epidemiology Study On Three Upper Gastrointestinal Cancers Of Shenqiu Country In Huai River Basin

ObjectiveTo study the phenomenon of high incidence of cancer in Huaihe River Basin, Shenqiu County of Henan Province was selected as the study area. Various methods such as spatial epidemiology, ecological epidemiology, environmental epidemiology and descriptive epidemiology(case-control study) were used to investigate and evaluate historical and current condition of industrial pollution, agricultural pollution and domestic pollution of this region, to find the specific pollutants and their sources leading to water pollution and high incidence of esophageal cancer, gastric cancer and liver cancer, to evaluate the relationship between environmental factors, behavioral lifestyle factors and the three types of cancer, to explore the possible carcinogenic factors, cancer-promoting factors and protective factors, trying to build the cause-chain from pollution to cancer.Methods and Results1. Survey on agricultural pollution in Shenqiu CountyThe data on the amount of pesticides and fertilizers from1984to2005was collected in detail for descriptive analysis. The results showed the level of nitrogen surplus from1985to2005was in an upward trend in general. Since2000, the amount of nitrogen fertilizer usage in Shenqiu County has been at a higher level and reached dangerous level to some extent. Pesticide use has been at a high level, And vice versa the corresponding pollution.2. Survey on Industrial pollution in Shenqiu CountyData on the type, size, number and geographical distribution of polluting enterprises(including existing enterprises and discontinued enterprises since1985) in Shenqiu County and Shaying River upstream region was collected. The production process, types of potential pollutants and waste emissions profile was also collected. The results showed the major polluting industries of current and historical enterprises was leather, paper, chemical, printing and plastics, which discharged plenty of waste water containing various organic pollutants, heavy metals and inorganic substances, of which many are group1(carcinogenic to humans) or group2(probably or possibly carcinogenic to humans) carcinogens identified by the International Cancer Research Center (IARC).3. Survey on environmental sanitation and pollution in cluster of digestive tract cancer in Shenqiu CountySpatial hotspot exploration technology was used to distinguish the high cluster and low cluster area of digestive tract cancer in Shenqiu County, then status of environmental sanitation and environmental pollution was investigated in both high cluster and low cluster to evaluate the correlation between environmental pollution and aggregation of digestive tract cancers. The survey showed the sanitation situation of both the high cluster and low cluster was poor. Proportion of polluted rivers, ditches, ponds was high. The number of polluting industries10years ago or20years ago was significantly related with clustering of gastrointestinal cancer, of which OR values were5.932and5.218respectively.4. Detection and analysis of water samplesAccording to the results of environmental survey in Shenqiu County, water sampling spots were determined and Shaying river water, pond water, well water samples were collected. Volatile and semi-volatile organic pollutants in water samples was detected by gas chromatography-mass spectrometry detected, semi-volatile organic compounds by solid phase extraction/gas chromatography-mass spectrometry, algal toxins by HPLC.A total of390kinds of organic pollutants were detected in the water samples of Liuji through the whole spectrum analysis including228species in surface water and232species in well water, of which the peaks of dibutyl phthalate, y-sitosterol and fucose sterol in surface water and well water were significantly higher than other components, suggesting these pollutants may be the priority control pollutants of surface water and well water in this area.Environmental endocrine disruptors such as dibutyl phthalate (PAE), nonylphenol (NP), bisphenol A (BPA) were detected in the water samples. Results of Microcystin(MCs) detection showed the concentration range of MCs was among0-2.298μg/L and the average concentration of MCs in four types of water samples in the order was:river water> pond water> shallow well water> deep well water.5. Carcinogenic activity analysis of water samplesCarcinogenic activity detection of water samples was detected through the refined Balb/c3T3cell transformation methods. Results showed surface water of high contamination area in Shenqiu County is of high cell-toxic and carcinogenic activity, and the raw water has been the ability to promote cell transformation. The carcinogenicity of well water decreased with the depth increasing. After high enrichment, shallow well water less than10meters showed carcinogenic activity, while40-meter-deep well water did not show the ability to promote cell transformation.6. Case-control studyA population-based case-control study, selecting local30-70year-old patients and controls, was adopted to study the relationship between environmental factors, behavioral lifestyle factors and esophageal cancer, gastric cancer and liver cancer.Main results of esophageal cancer cases-control study:drinking time of water sources surrounded by pollution in esophageal cancer group was significantly longer than that of control group, so was decentralized water supply; history of esophageal cancer in first-class relatives or second-class relatives was a significant risk factor; social psychological factors such as negative life-events, bad sleep, easily getting angry were significantly associated with esophageal cancer. Drinking tea, light diet, partial cool and soft food, frequent intake of potatoes, pepper, garlic, nuts and fruits showed protective effect against esophageal cancer.Main results of gastric cancer case-control study:drinking time of water sources surrounded by pollution in gastric cancer group was significantly longer than that of control group, so was decentralized water supply, suggesting water sources surrounded by pollution and decentralized water supply may be risk factors for gastric cancer, whereas water sources without pollution and drinking deep-well water may be protective factors. Gastric cancer showed the characteristic of familial aggregation:history of gastric cancer in first-class relatives was significantly associated with occurrence of gastric cancer. Social psychological factors such as negative life-events, bad sleep, easily getting angry could significantly enhance the risk of gastric cancer. Drinking tea, light diet, partial soft food, frequent intake of potatoes, peppers and fruits showed protective effect against gastric cancer.Main results of liver cancer case-control study:drinking time of water sources surrounded by pollution in liver cancer group was significantly longer than that of control group, so was decentralized water supply, suggesting water sources surrounded by pollution and decentralized water supply may be risk factors for liver cancer, whereas water sources without pollution and drinking deep-well water may be protective factors. Hepatitis B infection significantly increased the risk of liver cancer (OR=15.263), suggesting hepatitis B infection was an important risk factor. Family history of liver cancer was significantly associated with liver cancer. Social psychological factors such as negative life-events, easily getting angry made the risk of liver cancer higher. Light diet, frequent intake of potato, pepper, eggs and fruits showed protective effect against liver cancer.The common risk factors and protective factors of esophageal cancer, gastric cancer and liver cancer were identified:the common risk factors of three upper gastrointestinal cancers were distributed water supply, water sources surrounded by pollution, family history of cancer among first-class relatives, easily getting angry. Poor sleep, daily alcohol consumption, severe physical activity were common risk factors of esophageal and gastric cancer. The common risk factors esophageal cance rand liver cancer were related to age of first regular smoking less than20years-old, negative life events and family history of cancer among second-class relatives. The common protective factors of three cancers included pollution-free water sources, light diet, partial soft foods, frequent intake of potatoes, peppers and fruits. Drinking tea showed protective role for gastric cancer and esophageal cancer, drinking deep-well water for gastric cancer and liver cancer.Conclusion1. Through comprehensive analysis of environmental sanitation survey, agricultural pollution and industrial pollution survey, case-control study and water detection in Shenqiu County, it was preliminary determined that industrial pollution, agricultural pollution and domestic pollution were all associated with the occurrence of esophageal cancer, gastric cancer, liver cancer.2. Lifestyle factors, social psychological factors and genetic factors still played important role in the occurrence of esophageal cancer, gastric cancer and liver cancer.3. To explore the specific cancer-causing pollutants (such as MCs), the cause-chain from pollution to cancer was build basically:source of pollution--surface water--drinking water---disease and cancer.