RESUMEN
In this paper, we summarize exposure-related issues to consider in determining the most appropriate age ranges and life stages for risk assessment. We then propose a harmonized set of age bins for monitoring and assessing risks from exposures to chemicals for global use. The focus is on preconception through adolescence, though the approach should be applicable to additional life stages. A two-tiered set of early life age groups is recommended. The first tier involves the adoption of guidance similar to the childhood age groups recommended by the U.S. Environmental Protection Agency, whereas the second tier consolidates some of those age groups to reduce the burden of developing age-specific exposure factors for different regions. While there is no single "correct" means of choosing a common set of age groups to use internationally in assessing early life exposure and risk, use of a set of defined age groups is recommended to facilitate comparisons of potential exposures and risks around the globe, the collection of data and analyses of aggregate exposure and cumulative risk. Application of these age groups for robust assessment of exposure and risk for specific populations will require region-specific exposure factors as well as local environmental monitoring data.
Asunto(s)
Exposición a Riesgos Ambientales/efectos adversos , Contaminantes Ambientales/química , Contaminación Ambiental/efectos adversos , Animales , Monitoreo del Ambiente/métodos , Humanos , Medición de Riesgo/métodos , Estados Unidos , United States Environmental Protection Agency , Organización Mundial de la SaludRESUMEN
Young children have a greater ventilation rate per body weight or pulmonary surface area as compared to adults. The implications of this difference for inhalation dosimetry and children's risk assessment were evaluated in runs of the U.S. Environmental Protection Agency (U.S. EPA) 1994 reference concentration (RfC) methodology and the ICRP 1994 inhalation dosimetry model. Dosimetry estimates were made for 3-mo-old children and adults for particles and Category 1 and 2 reactive gases in the following respiratory-tract regions: extrathoracic (ET), tracheobronchial (BB), bronchioles (bb), and pulmonary (PU). Systemic dosimetry estimates were made for nonreactive (Category 3) gases. Results suggest similar ET dosimetry for children and adults for all types of inhaled materials. BB dosimetry was also similar across age groups except that the dosimetry of ultrafine particles in this region was twofold greater in 3-mo-old children than in adults. In contrast, the bb region generally showed higher dosimetry of particles and gases in adults than in children. Particle dose in the PU region was two- to fourfold higher in 3-mo-old children, with the greatest child/adult difference occurring for submicron size particles. Particulate dosimetry estimates with the default RfC methodology were below those found with the ICRP model for both adults and children for submicrometer sized particles. There were no cases in which reactive gas dosimetry was substantially greater in the respiratory regions of 3-mo-old children. Estimates of systemic dose of Category 3 gases were greater in 3-mo-old children than in adults, especially for liver dose of metabolite for rapidly metabolized gases. These analyses support the approach of assuming twofold greater inhalation dose in children than adults, although there are cases in which this differential can be greater and others where it can be less.
Asunto(s)
Envejecimiento , Contaminantes Ambientales , Gases/metabolismo , Sistema Respiratorio , Administración por Inhalación , Adulto , Animales , Contaminantes Ambientales/administración & dosificación , Contaminantes Ambientales/metabolismo , Femenino , Humanos , Lactante , Masculino , Tamaño de la Partícula , Sistema Respiratorio/crecimiento & desarrollo , Sistema Respiratorio/metabolismoRESUMEN
Parents in all countries want and deserve safe and healthy environments for their children. Children in all countries need, as part of normal growth and development, regular and frequent opportunities to interact with their environments as they learn to crawl, run, climb, swim, and explore. Environmental scientists and regulators recognize that environmental hazards are not contained by international borders. This is of special concern for children, because they are intrinsically at greater risk, compared to adults. They have different opportunities for exposure, greater response to certain toxicants, and less empowerment to alter their environments. There is a growing awareness that adverse health effects in children can adversely affect a country's future productivity and well-being. Multiple government agencies, NGOs, and advocates are mobilizing to address these concerns. A sustained concerted effort will be needed to afford equitable and effective environmental health protection to the world's children, present and future.