Ginsberg Gary L, Asgharian Bahman, Kimbell Julia S, Ultman James S, Jarabek Annie M
Connecticut Department of Public Health, Hartford, CT 06134, UAS.
J Toxicol Environ Health A. 2008;71(3):166-95. doi: 10.1080/15287390701597889.
Risk assessment of inhaled toxicants has typically focused upon adults, with modeling used to extrapolate dosimetry and risks from lab animals to humans. However, behavioral factors such as time spent playing outdoors may lead to more exposure to inhaled toxicants in children. Depending on the inhaled agent and the age and size of the child, children may receive a greater internal dose than adults because of greater ventilation rate per body weight or lung surface area, or metabolic differences may result in different tissue burdens. Thus, modeling techniques need to be adapted to children in order to estimate inhaled dose and risk in this potentially susceptible life stage. This paper summarizes a series of inhalation dosimetry presentations from the U.S. EPA's Workshop on Inhalation Risk Assessment in Children held on June 8-9, 2006 in Washington, DC. These presentations demonstrate how existing default models for particles and gases may be adapted for children, and how more advanced modeling of toxicant deposition and interaction in respiratory airways takes into account children's anatomy and physiology. These modeling efforts identify child-adult dosimetry differences in respiratory tract regions that may have implications for children's vulnerability to inhaled toxicants. A decision framework is discussed that considers these different approaches and modeling structures including assessment of parameter values, supporting data, reliability, and selection of dose metrics.
吸入性毒物的风险评估通常侧重于成年人，通过建模将实验动物的剂量测定和风险外推至人类。然而，诸如在户外玩耍时间等行为因素可能导致儿童接触更多的吸入性毒物。根据吸入的物质以及儿童的年龄和体型，由于每体重或肺表面积的通气率更高，儿童可能比成年人接受更高的体内剂量，或者代谢差异可能导致不同的组织负荷。因此，需要调整建模技术以适用于儿童，以便在这个潜在易感的生命阶段估计吸入剂量和风险。本文总结了2006年6月8日至9日在美国华盛顿特区举行的美国环境保护局儿童吸入风险评估研讨会上的一系列吸入剂量测定报告。这些报告展示了现有的颗粒和气体默认模型如何适用于儿童，以及呼吸道中毒物沉积和相互作用的更先进建模如何考虑儿童的解剖学和生理学。这些建模工作确定了呼吸道区域中儿童与成人剂量测定的差异，这可能对儿童吸入毒物的易感性产生影响。文中讨论了一个决策框架，该框架考虑了这些不同的方法和建模结构，包括参数值评估、支持数据、可靠性和剂量指标选择。
