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INCORPORATING NONCHEMICAL STRESSORS INTO CUMMULATIVE RISK ASSESSMENTS
Rider, C. V., M. Dourson, R. C. Hertzberg, M. M. Mumtaz, P. S. Price, AND J. E. SIMMONS. INCORPORATING NONCHEMICAL STRESSORS INTO CUMMULATIVE RISK ASSESSMENTS. TOXICOLOGICAL SCIENCES. Society of Toxicology, RESTON, VA, 127(1):10-7, (2012).
The workshop was put together to stimulate discussion on the emerging topic of including the impact of nonchemical stressors when considering the human health risk from exposure to either individual chemicals or mixtures ofchemicals. Experts in various disciplines (exposure analysis, mathematical modeling, risk assessment, toxicology) who have experience with either chemical mixtures or both chemical mixtures and joint consideration of chemical and nonchemical stressors were invited to give presentations
The risk assessment paradigm has begun to shift from assessing single chemicals using "reasonable worst case" assumptions for individuals to considering multiple chemicals and community-based models. Inherent in community-based risk assessment is examination of all stressors affecting a defined population including both the complex milieu of chemicals to which the community members are exposed and its specific vulnerabilities. Nonchemical stressors make up an important subset of community vulnerabilities that have the potential to either directly affect the health of individuals or modulate their response to chemical exposures. Strides have been made in developing methods for conducting cumulative risk assessment for multiple chemicals, but integrating nonchemical stressors represents a new challenge. Defining "nonchernlcal stressor" in the context of risk assessment is difficult due to the diversity of mental and physical stimuli that fall under this umbrella term. Further, distinguishing nonchem ical from chemical stressors can be problematic as physiological responses to nonchemical stressors and chemical stressors may be mediated by molecular signaling along the same biochem ical pathways. Nonchemical stressors are defined here as physical or psychosocial challenges and cumulative risk assessment as including both chemical and nonchemical stressors. Examples of physical stressors include noise, temperature, visual light, and atmospheric pressure . Psychosocial stressors can arise from deficiencies in the quality of one's environment (e.g. housing, sanitation) or resources (e.g. schools, access to medical care) and negative social factors (e.g. crime) . Nonchemical factors are known to impact health, although often with rough descriptions. Heat impairs judgment , cultural and socioeconomic factors (SES) affect susceptibility to environmental pollutants, and vibration alters cardiovascular function . In addition, some evidence of interactions exists, including noise and solvents jointly affecting hearing , chemical exposure affecting susceptibility to disease , and anxiety and stress enhancing chemical toxicity .