NIOSH Incorporates Written Plans in Risk Assessment Process
A NIOSH document released in March describes the agency’s process for conducting chemical risk assessments. As explained in “Current Intelligence Bulletin 69: NIOSH Practices in Occupational Risk Assessment” (PDF), the process involves determining the type of hazard associated with an agent, collecting evidence, evaluating data, determining how much exposure would be harmful to workers, and making recommendations regarding risk. According to the document, the purpose of NIOSH risk assessments is to determine the relationship between exposure and health effects. The risk assessment is expected to produce either a Recommended Exposure Limit or a Risk Management Level for Carcinogens, which represents the daily maximum 8-hour time-weighted average concentration of a carcinogen above which workers should not be exposed (PDF). The new NIOSH risk assessment process involves a written risk assessment plan, not included in previous NIOSH criteria documents and current intelligence bulletins, that describes a conceptual model of the hazard, people at risk, and potential adverse effects; and identifies the risk-related metrics to be used. NIOSH does not include an exposure assessment step, explaining that an exposure assessment typically applies to a specific population of workers and is not necessary for the agency because the NIOSH mission is to protect all workers. Other steps in the NIOSH risk assessment process include hazard identification, dose-response assessment, and risk characterization. The NIOSH document endorses a weight-of-evidence approach when assessing the quality of studies during the hazard identification step. The factors NIOSH will consider in assessing the quality of a study include strength of association, consistency, specificity, plausibility, and coherence, among others.