is marker for indicates clinical effect of Clarification: An 'exposure agent' can be either a medical product or some substance (e.g., pesticide) , physical factor (e.g., radiation), or organism (e.g., virus) that originates from the environment. Usage note: This does not imply that 'b' and exposure to 'e' are in a direct causal relationship, as it may be the case that there is a third entity 'a' that stands in a direct causal relationship with 'b' and exposure to 'e'. Basis: This relation is an umbrella for a set of relations that are based on the 'BEST' classification of and definition for 'biomarker', as given by the FDA-NIH Biomarker Working Group: A defined characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or biological responses to an exposure or intervention, including therapeutic interventions. The BEST classification includes diagnostic, prognostic, susceptibility/risk, monitoring, predictive, safety, and pharmacodynamic/response biomarkers. See PMID:29405771 for details. Note that any given biomarker can be of a different type in different contexts. An image biomarker showing tumor size indicates_clinical_effect_of some radiotherapy. A relationship between a biomarker 'b' and an exposure agent 'e', where the effect of exposure to 'e' is correlated with the presence or occurrence of 'b', and the observation of 'b' is used to infer exposure to 'e'.