蘭陽盆地居民飲用之地下水中無機砷及其他元素含量與癌症發生之
相關性研究
A Study on the Association between Inorganic Arsenic and other Elements in Well Water and Cancer Incidences among Residents of Lanyang Basin
中文摘要
無機砷是已知人類的致癌物質，會導致全癌、肺癌、肝癌、泌尿道癌等癌症，並有顯著的劑量效 應關係，這些結果已於台灣西南沿海高砷地區的諸多研究加以支持。近年來並在蘭陽盆地發現地 下井水含砷濃度偏高，如果砷的致癌性確實，則蘭陽盆地居民的癌症高發生部位是否與台灣西南 沿海居民相似。又地下水成分複雜，包含許多其他無機金屬元素，是否其中仍有砷以外的元素，
對各種砷引起的癌症有單獨作用，或與砷的交互作用，亦需加以釐清。本研究共分二部份探討蘭 陽盆地無機砷及其他地下井水主要成分與各種癌症的相關性，並比較其與台灣西南沿海高砷地區 的疾病狀態是否相同。第一部份為蘭陽盆地無機砷癌之世代追蹤研究：以過去在礁溪、壯圍、冬 山、五結四鄉十八村所建立的 8102 人為研究世代，進行追蹤問卷訪視、死亡診斷書蒐集及全 國死亡檔、癌症登記檔比對，以分析該世代之癌症的發生率，並探討無機砷暴露與這些癌症的相 關性。結果顯示，不分性別，本研究世代之全癌症、鼻咽癌、胃癌、小腸癌、大腸直腸癌、肝癌、
膽囊癌、鼻腔癌、肺癌、婦女癌症(乳房、子宮頸、卵巢)、泌尿道癌等，標準化發生比均高於同 年齡層之台灣地區民眾，且均達統計顯著水準。將飲用水含砷濃度(μg/L)分成≦10, 10.1-50,
>50 三組分析，顯示大腸直腸癌及泌尿道癌之性別、年齡別直接標準化發生率(每十萬人)，存 在隨飲水砷濃度增加而升高之劑量效應關係。研究世代之癌症別發生相對危險性與砷暴露指 標之單變項分析中，不論就飲用水含砷濃度或累積砷暴露量而言，全癌症、肺癌、泌尿道癌等在 最高暴露組均有顯著偏高的情形；當調整年齡、性別、抽菸習慣及喝酒的作用後，累積砷暴露量 最高暴露組的全癌症、肺癌、泌尿道癌的發生相對危險性分別為最低暴露組的 1.7、2.6、8.0 倍，且均達統計顯著水準；而抽菸與累積砷暴露量對全癌症、肺癌、泌尿道癌的年齡、性別調整 之發生危險性有加成性協同作用。第二部份為蘭陽盆地地下井水成分元素分析：本研究以感 應耦合電漿-原子發射光譜儀(ICP-AES)，再加上氫化產生裝置，針對分層抽樣自上述四鄉十八 村已測過砷濃度的井共 1349 口，作微量分析，以瞭解井水中所含元素種類及濃度，期能評 估各種元素與砷癌的相關性，進一步釐清這些元素是否對砷的致癌性具有作用。本研究共分析 鋅、鈉、鈣、銅、鐵、錳、鎂、鉻、鍶、鋇、鎘、鈹、硼等 13 個元素。結果發現，各元素的 濃度分佈變異極大，其中鈣、鐵、錳、鉻、鋇、鈹與砷的濃度變化有明顯相關，但相關係數偏低 (<0.3)；錳與銅對癌症的發生具有保護效果，但與砷之間並無明顯的交互作用，顯示飲水 中仍以砷可能為主要致病因子。
英文摘要
Cancers of the skin and lung induced by inorganic arsenic has been well recognized
by the International Agency for Research on Cancer (IARC). The association between long-term inorganic arsenic exposure and cancers had been reported in many studies carried out in Taiwan. In order to reprove the carcinogenic effect of ingested inorganic arsenic, Chiaoshi, Chuangwei, Tungshan and Wuchien townships in Ilan County, where the arsenic level in well water is highly variable were selected as study area.
This is the first study to assess the dose-response relationship between cancer risks and long-term individual exposure to inorganic arsenic. A total of 276 cancer
incidences cases were found among 8102 subjects during six-year follow-up period. A significantly higher incidence from cancers of the stomach, colorectum, liver, lung, gyneology, and urinary organs was observed among residents in the study area compared with the general population in Taiwan. Incidences of various cancers were positively correlated with age, habits of cigarette smoking, arsenic content in well water, and cumulative arsenic exposure. Men have higher various cancer incidences than women have. After adjustment for age, sex, and cigarette smoking, the
multivariate-adjusted relative risk and its 95% confidence interval of cancers from all sites combined, lung, urinary, were 1.4 (1.0-1.9), 2.5 (1.2-5.1), and 4.8 (1.2-19.4), respectively, for arsenic content in well water greater than 100 ug/L; 1.7 (1.2-2.5), 2.6(1.2-5.5), and 8.0 (1.6-39.9) for cumulative arsenic exposure larger then 5
mg/l-year. There was a significant dose-response relationship between urinary cancers and arsenic content in well water. Our study also found that both arsenic exposure and cigarette smoking have a significantly synergistic effect on risks of cancers from lung and urinary among study subjects. ICP-AES was used to look into the content of elements in well water. We didn't find any elements in well water that
significantly correlated to the carcinogenic ability of arsenic. Our large cohort study indicates that long-term exposure to inorganic arsenic based on more precise
estimation of individual exposure among study subjects will increase risks of various cancer sites.
