ABSTRACT: Health impact assessments (HIA) have become an important tool for applying evidence-based policy. Recently, the concept of HIA has been introduced in the field of chemical substances. Two main issues are encountered, i.e., the focus of risk assessment is deriving safe levels and on first signs of adverse effects. These adverse effects, often at a subclinical level, fall outside the scope of a HIA. However, the number of subjects with subclinical effects can be extensive, thus relevant to consider in HIA and subsequent risk management policies and socioeconomic analyses (e.g., under REACH). The approach to include subclinical effects in a HIA relies on the dose–response relationship for toxicological endpoints, which are indicative for subclinical and clinical effects. Assessment of (sub)clinical effect sizes requires expertise from toxicologists, pathologists, and risk assessors. The clinical effect is appraised by a disability weight in the disability adjusted life year (DALY) concept. Subsequently, a derivative thereof, the severity weight, is assigned to parameter value changes in the range of subclinical effect sizes to appraise subclinical effects. Ultimately, if the approach is repeated for many substances, severity weights may be assigned based on changes in endpoints alone, making it a valuable tool for health impact assessors of chemical substances.