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ASSESSING THE HEALTH EFFECTS AND RISKS ASSOCIATED WITH CHILDREN’S INHALATION EXPOSURES – ASTHMA AND ALLERGY
SELGRADE, M. K., C. PLOPPER, M. I. GILMOUR, R. CONOLLY, AND B. FOOS. ASSESSING THE HEALTH EFFECTS AND RISKS ASSOCIATED WITH CHILDREN’S INHALATION EXPOSURES – ASTHMA AND ALLERGY. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH - PART A: CURRENT ISSUES. Taylor & Francis, Inc., Philadelphia, PA, 71(3):196-207, (2007).
Because asthma is a complex disease involving multiple genes, multiple phenotypes, and several organ systems and because air pollution is a complex mixture, this area may be particularly in need of newer systems biology approaches.
Adults and children may have different reactions to inhalation exposures, which may be the result of differences in inhaled or target tissue doses following similar exposures, and/or due to growth and development of the lung which continues postnatally in distinct stages. Because asthma and allergy are immune mediated diseases both the developing immune system and initial encounters with common allergens contribute to the differential susceptibility of children. Asthma, the most common chronic childhood disease, has significant public health and economic impacts. It is characterized by chronic lung inflammation, reversible airflow obstruction, and immune sensitization to common allergens. Air pollutants can exacerbate symptoms in asthmatic individuals and may also play a role in induction of disease. Animal studies have demonstrated the effects of air pollutants on allergic lung disease. Changes characteristic of allergic asthma were observed in rhesus monkeys sensitized to house dust mite antigen (HDMA) as infants and exposed repeatedly thereafter to 0.5 ppm ozone and HDMA for a period of 11 weeks. Airway growth and development were compromised and modifications suggestive of airway remodeling were observed. O3 exposure exacerbated the allergen response to favor development of intermittent airway obstruction associated with wheeze. In Brown Norway rats a variety of air pollutants enhanced allergic sensitization to HDMA such that symptoms elicited in response to subsequent allergen challenge are more severe. Although very useful for assessing the impact of air pollutants on initial allergen sensitization, the rodent immune system is relatively immature at birth compared to human, making this model less useful for studying other of differential effects between adults and children. Currently there are limited applications of computational modeling available to address children’s inhalation exposures. Thus, default adjustments and their associated uncertainty will continue to be used in children’s inhalation risk assessment.