indicates clinical effect of monitors exposure to https://orcid.org/0000-0001-5809-9523 The concentration of tobacco specific nitrosamines in urine monitors_exposure_to tobacco/tobacco smoke. A relationship between a serially-measured biomarker 'b' and an exposure agent 'e', where 'b' is used to provide evidence of exposure to 'e'. 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: The relations 'monitors status of' (RO:0020328), 'monitors exposure to' (this relation), and 'monitors effect of' (RO:0020335) are each used for serially-measured biomarkers: - 'monitors status of' pertains to cases where the biomarker is used to assess the progression/remission of a disease or condition of clinical interest; - 'monitors exposure to' pertains to cases where the biomarker is used to assess the occurrence of or amount of exposure to some exposure agent; - 'monitors effect of' pertains to cases where the biomarker is used to assess any possible biological effect arising from exposure to some exposure agent. Basis: This relation is 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. Darren A. Natale