Study On Ecological Geochemistry Of Regional Cancer In The Pearl River Delta Area

Medical opinion had it that cancer is exploding in the world.80%-90% of the cancer cases are related to environmental factor.The International Agency for Research on Cancer(IARC)indicated that the incidence and mortality of cancer has significant regional characteristics.In order to prevent and reduce the incidence of cancer,it is important to study the relationship between environmental factors and cancer incidence.In this paper,the high incidence areas in the Pearl River Delta region of liver and nasopharyngeal cancerwas selected as the study area.The environmental carcinogenic factors were concerned for many years in this area.Base on the 1:50,000 soil eco-geochemical detailed survey projects,the human source and natural source of the geochemical carcinogenic factors would be distinguished by analyzing the heavy metal elements anomaly in soil and the inorganic nitrogen and N-nitrosamine in environment water and drinking water.The behaviors of the geochemical carcinogenic factors also would be hunted in this paper.Finally,combining with the distribution of cancer incidence in the study area,we will research the main geochemical carcinogenic factors which may lead the high incidence of cancer cases in this paper.The results showed that: 1)The N-nitrosamines were detected in the the environmental water and drinking water of high cancer incidence area--Sihui,Zhongshan,Shunde,Foshan and Fusui.The N-nitrosamines are carcinogenic factors.Shunde area had the highest content of nitrosamine in water.The average concentration of the N-nitrosamine compounds in the fifteen water samples from Shunde is 62.9ng/L,and the average concentration of the N-Nitrosodimethylamine(NDMA)is 35.1ng/L,which is five time higher than the limited value of drinking water health standards.2)NDMA is widely existed in the water and the concentration was relatively high.The concentration is steady(NDMA ranging from 22 ng/L to 30ng/L)in the running water from the Pearl River Delta area.We considered that it is related to the addition of chlorine-containing disinfectant during the productive process.However,the oncentration of NDMA in natural water has large difference(NDMA ranging from 2.1 ng/L to 114.0ng/L),we considered that the source mainly from the high ammonium groundwater and industrial wastewater.3)High ammonium in the underground water,and added with the anthropogenic pollution,the highest concentration of N-nitrosamine was emerged in environment water of Shunde area.The situation of environment water in Zhongshan and Foshan are similar to Shunde,which also showed the characteristics of the high-Ammonia-Nitrogen & anthropogenic pollution.Because of the low industrial development in Sihui area,the combination of nitrosamines may be closer to the original assemblage of nitrosamine in underground water.4)In Fusui region of Guangxi Province,the formation conditions of the Nitrosamines are similar to the Pearl River Delta area.However,the less polluted environment water leads to the low content of Nitrosamines,and the combination of nitrosamines may be closer to the original assemblage of nitrosamine in underground water.5)Heavy metal elements are highly enriched in the soil from Shunde area and this enrichment were affected by anthropogenic pollution source and natural source.The heavy metal elements were enriched varying degrees in the soil from the research areas.The most serious pollution area is Shunde area.Three abnormal enrichment areas were formed in Shunde area.6)The results show that no significant relation exist between the distributions of heavy metals enrichment areas and the distribution of the incidence of cancer.The carcinogen N-nitrosamine and its precursor were detected from the environmental water and drinking water,is probably the major geochemical carcinogenic factors in the high cancer incidence in our study area.