健康風險評估是量化分析特定人類活動或經由該類活動所釋放毒性化學物質對個體及群體可生成危害機率之過程。隨著評估技術日臻完備，健康風險評估已逐步應用於作業環境中化學毒物暴露危害之評估，以輔助職業暴露限制值（Occupational Exposure Limit, OEL）之建立與管制措施之選用。本文探討健康風險評估於OEL制定之應用現況與趨勢，主要針對美國職業安全衛生署（US Occupational Safety and Health Administration, OSHA）制定其容許濃度限制值時應用健康風險評估技術之特色討論。整體而言，針對OEL制定所進行之健康風險評估，在典型假設與分析方法各方面，與在其他領域進行者相較具獨特性。如OSHA在制定其容許暴露限制值時，考量作業環境與一般環境相比具暴露濃度較高與受暴露個體間變異性較小之特性，同時因應美國最高法院對控管技術與經濟層面可行性考量之要求，在評估過程中慣於發展符合政策需求之典型假設，諸如致癌性評估中逾量風險值之設定、不確定性因子之安全係數運用、以及暴露評估之參數設定等。如我國相關權責單位考慮建立健康風險評估在OEL制定上之運用規範，建議針對評估技術於OEL制定時之獨特性進一步探討，包括健康風險評估中暴露評估部分所使用之暴露參數規範，以及評估過程所使用不確定性係數之運用規則。

Health risk assessment is the process of quantifying the probability of a harmful effect to individuals or populations from intended human activities or due to the release of hazardous substances from such activities. With its techniques maturing, health risk assessment has been applied in the development of occupational exposure limits (OELs) for controlling the exposure of workers to toxic industrial chemicals and selection of managerial schemes. This article reviewed the current use of health risk assessment in the OEL development and future trend, focusing on the assessment techniques distinctly applied in the development of Permissible Exposure Limits (PELs) by the US Occupational Safety and Health Administration (OSHA). As our discussion showed, the health risk assessment practiced in the OEL development was unique in the default assumptions made and the methodologies employed compared to those practiced in other fi elds. For instance, when developing a PEL, the OSHA considered the intensity of exposure in the workplace generally greater and the variability among exposed individuals less than those observed in the ambient environment. The OSHA was also required by the US Supreme Court to consider the technological and economical feasibility of pursuing compliance to a proposed PEL. As a result, the OSHA developed unique policy decisions on the techniques applied in its health risk assessment, such as the determination of excess risk of signifi cance defi ned in the cancer-based risk assessment, the use of safety factors accounting for uncertainty, and the parameters assumed in the exposure assessment. If health risk assessment is preferred in the development of Taiwanese OELs, some unique features in the assessment techniques may be further explored, including localizing the parameters used in exposure assessment and standardizing the uncertainty factors applied in interpreting dose-response relationship.