本文係綜論皮膚砷癌的流行病學特徵與危險因子。砷引起的皮膚癌屬於非黑色素瘤皮膚癌。一般的非黑色素瘤皮膚癌常見於白種人，男性比女性有較高的發生率。它好發於臉、頭及頸部，軀幹及上肢是次常發部位；而且隨日曬程度增加。紫外線輻射、化學物質、游離輻射線、免疫因素、宿主因素為其主要之危險因子。砷是一種類金屬，往往經由礦脈、銅精煉廠、工業和農業用途，造成環境的污染。引起健康危害的砷主要是無機砷，它會引起胃腸道障礙、心臟血管疾病、神經病變、肝腎障礙、皮膚病變和癌症。砷已被公認為人類之皮膚和肺的致癌物。砷引起皮膚的主要暴露途徑為藥物，環境和職業暴露。皮膚砷癌的發生部位大多為非日曬部位，即手掌、腳蹠、肢端和軀幹，且屬全身多發生的表皮癌化病變。臺灣西南沿海烏腳病盛行地區的皮膚癌盛行率及死亡率，與深井水含砷濃度呈劑量效應關係。吾人研究發現烏腳病高盛行地區的皮膚盛行率，與慢性砷暴露指標，包括烏腳病盛行地區居住年數、飲用深井水年數、飲用水平均砷濃度、和累積砷暴露等，均呈現顯著的劑量效應關係。皮膚砷癌盛行率也與從事鹽田工作、B 型肝炎帶原且肝功能不良、食用蕃薯簽年數偏高有顯著相關。人體內的無機砷代謝能力，尿液砷物種分佈，血清微量營養素濃度，以及免疫能力與皮膚癌的相關性，尚待進一步証實。皮慮病變可作為無機砷長期暴露的生物指標，過去在烏腳病盛行地區的研究指出，皮膚癌和內臟癌的標準死亡比與累積死亡率，都比臺灣地區一般人口顯著偏高。砷引起皮膚癌的機轉，以及皮膚癌與內臟癌之間的關係，均是值得探討的主題。

　　　　　Research on the epidemiologic characteristicsand risk factors of arsenic-induced skin cancer were reviewed in detail.Arsenic-induced skin cancers are nonmelanoma skin cancers. Nonmelanoma skincancers are much more common in white than in black or other dark- skinnedpopulations. The incidence of nonmelanoma skin cancer is greater in males thanin females. It occurs mostly on the face, head and neck, while the trunk andupper extremities are the next most common sites. The risk of nonmelanoma skincancer is asscciated with the sunlight exposure in a dose-response relationship.Ultraviolet radiation, chemicals, ionizing radiation, immunologic and other hostfactors are risk factors for nonmelanoma skin cancer. Arsenic is a metalloidelement, contaminating the environment through leaching from mineral ores,copper smelting, and other industrial and agricultural sources. Inorganicarsenic is much more toxic than organic arsenic compounds. It inducesgastrointestinal disturbance, cardiovascular diseases, neurological disorders,liver and kidney damage, skin lesions and cancers. Inorganic arsenic has beendocumented as a human carcinogen of the skin and lung. Exposure to inorganicarsenic from medicinal, environmental and occupational sources has been found tobe associated with the development of skin cancer. In contrast with nonmelanomacancers of other etiologies, arsenic-induced skin cancers occur on every part ofthe body, especailly marked in areas unexposed to sunlight, such as the palms,soles, extremities and trunk. They are multifocal and randomly distributedepidermal carcinoma lesions. A dose-response relationship between the prevalenceand mortality of skin cancer and the arsenic concentration of artesian wellwater has been well documented in a black- foot disease endemic area on thesouthwest coast of Taiwan. A significant dose-response relation has recentlybeen reported between skin cancer prevalence and chronic arsenic exposure,indexed by duration of living in the endemic area, duration of consuminghigh-ar- senic contaminated artesian well water, average arsenic in artesianwell water and cumulative arsenic exposure. Salt field working, chronic HBsAgcarrier status with liver dysfunction, and high consumption of dried sweetpotatoes have been found to be significantly associated with an increasedprevalence of arsenic-induced skin cancer in those living in the blackfootdisease endemic area. Arsenic metabolism capacity, distribution of urinaryarsenic species, serum level of micronutrients and immunologic profiles need tobe explored for their associations with arsenic-induced skin cancer. Skin cancerhas been considered as a biological marker for chronic inorganic arsenicexposure. Both standardized mortality ratio and cumulative mortality of skincancer and various internal cancers have been reported to be significanltyhigher among residents in the blackfoot disease endemic area than in the generalpopulation in Taiwan. The mechanism of arsenic-induced skin cancer as well asthe association between skin cancer and internal cancrs deserve furtherinvestigation.