title: Conceptual model for assessing criteria air pollutants in a multipollutant context: A modified adverse outcome pathway approach.
abstract: Air pollution consists of a complex mixture of particulate and gaseous components. Individual criteria and other hazardous air pollutants have been linked to adverse respiratory and cardiovascular health outcomes. However, assessing risk of air pollutant mixtures is difficult since components are present in different combinations and concentrations in ambient air. Recent mechanistic studies have limited utility because of the inability to link measured changes to adverse outcomes that are relevant to risk assessment. New approaches are needed to address this challenge. The purpose of this manuscript is to describe a conceptual model, based on the adverse outcome pathway approach, which connects initiating events at the cellular and molecular level to population-wide impacts. This may facilitate hazard assessment of air pollution mixtures. In the case reports presented here, airway hyperresponsiveness and endothelial dysfunction are measurable endpoints that serve to integrate the effects of individual criteria air pollutants found in inhaled mixtures. This approach incorporates information from experimental and observational studies into a sequential series of higher order effects. The proposed model has the potential to facilitate multipollutant risk assessment by providing a framework that can be used to converge the effects of air pollutants in light of common underlying mechanisms. This approach may provide a ready-to-use tool to facilitate evaluation of health effects resulting from exposure to air pollution mixtures.
authors.affiliation: National Center for Environmental Assessment, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711, United States. Electronic address: buckley.barbara@epa.gov.
authors.forename: Barbara
authors.initials: B
authors.lastname: Buckley
authors.affiliation: National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. EPA, Research Triangle Park, NC 27711, United States.
authors.forename: Aimen
authors.initials: A
authors.lastname: Farraj
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects*; D000818:Animals; D002318:Cardiovascular Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D004781:Environmental Exposure / Q000009:adverse effects; D004784:Environmental Monitoring; D005740:Gases; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects; D008171:Lung Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D008962:Models, Theoretical; D052638:Particulate Matter / Q000009:adverse effects*; D018570:Risk Assessment; D012307:Risk Factors
chemical_list: D000393:Air Pollutants; D005740:Gases; D052638:Particulate Matter
keywords: Adverse outcome pathway; Air pollution; Criteria pollutants; Multipollutant