珠江三角洲含N-亚硝胺地下水与地区性癌症

N-nitrosamine containing underground waters and regional cancer incidence in the Pearl River Delta region

肆虐我国南方局部区数百年以鼻咽癌和肝癌为主的恶性肿瘤病,为典型的地区性癌症。本文以珠江三角洲为例,应用流行病学与生态地球化学相结合的调查方法,检出了病区环境水和饮水中存在致癌物质N-亚硝胺,研究了癌病区生态系统由地质构造背景、气候、水文和生态条件制约,自然形成水体N-亚硝胺的机理。实验改进、优化了环境-饮水微量亚硝胺测定方法,新建立的固相萃取-气相色谱-串联质谱(GC/El-MS/MS)测定纳克级N-亚硝胺方法一次可测9种N-亚硝胺化合物,检出限达到0.34～2.19ng/L。在珠江三角洲癌病区环境-饮水中首次发现9种亚硝胺化合物,含量为307～0.34ng/L,总检出率为40%。四会等较低工业污染区古井水、手压井水和自来水的亚硝胺有相近似的含量统计特点:亚硝基二甲胺和亚硝基二正丁胺的均值和峰值为不高的超标值,均值分别为21.77和15.54ng/L。这批水样大多采自0～20m深度井水,属本区代表性特殊地质构造和气候生态环境中形成的地下水,也是研究区生产和生活开发最多的水源层;所含超标亚硝胺可能是本区数百年高发癌症的主因。近年工业发展带来的亚硝胺污染源的叠加,增高了该区环境-饮水亚硝胺超标率及癌症发病率。文中分析了珠江三角洲土壤和地下水富氮营养化现象和区域氮的来源。

Localized/regional nasopharyngeal and hepatocellular carcinoma in South China are the typical cancer types by regional malignant tumor,ravaging public health in the area for hundreds of years.In this paper,taking the centuries old regional carcinoma epidemic in the Pearl River Delta as an example,applying epidemiology and ecogeochemical methodology,we determined that both environmental and drinking waters contained N-nitrosamine,a known carcinogen.We investigated the formation mechanism of N-nitrosamines compounds in natural waters under the constraints of regional geological,climate,hydrologic and ecological conditions.We developed a solid-phase extraction method(SPE)adaptable to gas chromatography-mass spectrometric(GC-MS)analysis to detect nine trace N-nitrosamine compounds in environmental and drinking waters.The detection limit ranged from 0.34 to 2.19 ng/L.In two representative cancer high-risk areas,Shunde and Sihui,we performed for the first time quantitive analysis of nine trace Nnitrosamines in different water occurrences.The results showed that the N-nitrosamine concentrations in local waters ranged from 0.34 to 307 ng/L.And the detection rate of 40%was much higher than the 15%rate set by healthy drinking water standard for N-nitrosamines at 10 ng/L.The testing results indicated NDMA and NDBA were the main pollutants,while other nitrosamines were detected at lower concentrations.In the less industrialized Sihui area,nitrosamine concentrations share the same statistical characteristics for different water occurrences such as well,tap,underground and spring waters:the average and peak values of NDMA and NDBA barely exceeded the standards at 21.77 and 15.54 ng/L,respectively,higher than other nitrosamines.This was a typical nitrosamine composition profile for the natural regional underground water.The water samples were taken from wells at 0-20 mdepths.The underground water is ammonium-rich and contains nitrosamines formed under unique regional ecogeological and climate conditions,and it may be the original culprit of the regional carcinoma.Among the five endemic regions studied,the industrialized Shunde area has highest nitrosamine content,with nitrosamine concentration correlating positively with hepatocellular carcinoma morbidity.Our study confirmed that cumulative effect of industrial pollution can increase cancer morbidity.