要 癌症是一種複雜多誘發病因的疾病，因遺傳、環境或生活習慣交互作用造成基因突變 而發生；如果能發現危險因子加以控制，可能減少或避免癌症的發生。勞工在作業或製程 中可能暴露到致癌性危害，然而有許多原因使得要確定職業暴露與特定癌症發生的因果關 係極為困難，包括癌症的潛伏期較長且個體差異極大；出現初始臨床表癥或被診斷罹患癌 症時，勞工可能已自暴露職務離職。此外，目前對於致癌性危害的研究有限，缺乏足夠的 證據或資訊來評估危害的健康效應。再者，罹癌勞工可能同時暴露不等數量或劑量的職業 性或非職業性致癌因子，而雇主、勞工或醫師往往對勞工暴露之致病性危害因子缺乏警覺 等。 在2012年，日本厚生勞働省基於3名罹患膽管癌的膠版印刷工人提出之職災補償申請， 進行一系列調查後懷疑與1,2-二氯丙烷或二氯甲烷等有機溶劑的暴露有關，這是全世界初次 的叢聚性職業性膽管癌案例報告。根據這個報告，日本政府在2014年9月將1,2-二氯丙烷的 管理濃度由10 ppm調降至1 ppm。 我們希望藉由回顧此案例於日本認定過程與相關文獻，提醒職安衛人員或醫護人員重 視職業危害因子暴露對疾病發生的影響，也呼籲主管機關加速職業安全健康保護相關法規 與職業危害資料庫的修訂，以加強對勞工安全健康之保護。

Cancer risk is complex and multifactorial, with genetic, environmental, and lifestyle factors interacting to cause disease as a consequence of genetic mutations. Cancer may potentially avoidable if the risk factors are controlled. Workers can be exposed to carcinogenic hazards in the work environment or during the process. However, it is difficult to determine the causal relationship between occupational carcinogen exposures and certain types of cancer. First, cancer is a disease with a long or varied latency period. Workers usually presented clinical manifestations or were diagnosed after leaving the exposed job for many years. Second, there was limited evidence or information for the carcinogenicity of most occupational hazards. Third, individual worker might be exposed to different numbers or doses of occupational and non-occupational risk factors. Furthermore, most employee, employers, and physicians were not aware that what kinds of hazards were in the workplace. The above problems increase the difficulty of the recognition of the association between occupational carcinogens and cancer. In 2012, a series of surveys was conducted by the Japanese Ministry of Health, Welfare and Labor in response to a cluster report of 3 cholangiocarcinoma cases and inquiries about occupational cause. Exposure to organic solvents including 1,2-dichloropropane and/or dichloromethane is supposed to be associated with the carcinoma development. This was the first reported cluster of occupational cholangiocarcinoma. According to the report, the Japanese government had set an administrative control level of 1 ppm instead of the previous limit of 10 ppm for 1,2-dichlopropane in September 2014. In this review, we will introduce available information or evidence which support the association between suspected agents and cancer for Japanese printers. We hope to remind all occupational safety and health experts and medical personnel to pay attention to the association between hazards and diseases. We also suggest that the administration could accelerate the revision of the relevant legal rules and the update of occupational hazard database to enhance the protection of workers.