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Determination of hand soil loading, soil transfer, and particle size variations after hand-pressing and hand-mouthing activities
Citation:
Hsi, H., C. Hu, M. Tsou, H. Hu, H. Ozkaynak, K. Bradham, Z. Hseu, W. Dang, AND L. Chien. Determination of hand soil loading, soil transfer, and particle size variations after hand-pressing and hand-mouthing activities. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 627:844-851, (2018).
Impact/Purpose:
Human health risk assessment is the process for estimating the nature and likelihood of adverse health effects in humans resulting from present or anticipated exposures to chemicals in contaminated environmental media (U.S.EPA, 2004a). The assessment of exposures to chemicals from contaminated soil via ingestion and dermal contact pathways, requires gathering information on soil adherence to skin and its hand-to-mouth transfer. These parameters are then used to determine the magnitude of exposure risk, along with the data on the content and speciation of contaminants found in soil through chemical analysis.
Description:
Hand-pressing trials and hand-to-mouth soil transfer experiments were conducted to better understand soil loadings, soil transfer ratios for three mouthing activities, and variations in particle size distributions under various conditions. Results indicated that sand caused higher soil loadings on the hand than clay. When the moisture level of clay soil exceeded its liquid limit, soil loadings also increased. Greater pressing pressures also led to larger clay loadings. Clay with a moisture content close to its plastic limit caused the smallest soil loadings due to strong soil cohesion. Particle sizes of the transferred clay were larger than that of the original clay, indicating that hand-pressing and the pressure exerted may have enhanced clay particles of larger sizes adhering onto the hand. Nevertheless, the sizes of most particles that adhered to the hand were still smaller than 150 μm. Higher pressing pressures and greater moisture contents resulted in larger soil loadings on the hand, and transfer ratios became smaller. Transfer ratios from palm-licking with clay particles were smaller than those from finger-mouthing, which may have been due to finer particles that more readily adhered to the skin of the palm and that were transferred from the hand to the mouth with greater difficulty.
