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Year 102 Special report on Child-specific exposure factors of non-dietary ingestion, soil adherence

Harmful substances in soil and dust may enter into human body through direct pathways such as inhalation, digestion, and dermal contact causing adverse health effects. Owing to the difference in physical and physiological behaviors, infants and toddlers are less tolerant to toxic substances than adults, and the toxic substances can pose higher risk to children. Soil and dust ingestion thus becomes a critical exposure factor to determine the potential risk to children. The objective of this multiple year project is to establish a soil exposure database for infants and toddlers living around contaminated sites. In years 2011 and 2012, we have successfully obtained the soil/dust ingestion data for 0-5 years old infants and toddlers. One of the major objectives in this year is to complete the database by further examining the soil exposure data for 6 years old children, considering the different definition between Taiwan (children = a person ≤ 6 years old) and other countries (children = a person ≤ 5 years old). Moreover, two key parameters, the adherence to the skin of different parts of a body and the hand-to-mouth transfer ratio will be obtained by gravimetric method for the subsequent dermal contact absorption assessment. The gravimetric method determines the mass of soil washed from different parts of children’s body to examine the laboratory-based hand-to-mouth transfer of soil. The Stochastic Human Exposure and Dose Simulation (SHEDS), a well-recognized soil and dust ingestion rate model developed by the USEPA, will be applied using the Taiwan’s local inputs as model parameters to estimate the risk of soil and dust ingestion and dermal contact absorption for children. The model predictions will then be compared to the measurements upon individuals and to the overall distribution of soil and dust ingestion rates for the study population (i.e., comparison of measurements to the predicted soil and dust cumulative distribution functions). An international conference will also be held in Taiwan with an attempt on information/experience exchange and data comprehension/integration about the children exposure factor establishment and risk assessment between attendee, the external advisors in our team, and invited foreign experts .
Exposure factors;soil/dust ingestion;dermal contact absorption;Stochastic Human Exposure and Dose Simulation model (SHEDS)