Student Research: Carolyn Bergstrom
MS, , 2010
Particle Size Distributions, Size Concentration Relationships, and Adherence to Hands of Selected Geologic Media Derived from Mining, Smelting, and Quarrying Activities
Hand-to-mouth activity by young children is recognized as a potential pathway of exposure to soil contaminants. Observed soil and contaminant loads on hands are relevant to evaluation of this pathway. Soil adherence values based on common soils may or may not be appropriate estimators of hand loads of soil-like materials that contain large fractions of mining or smelting wastes or quarry product. The latter may also contain relatively high concentrations of elements of concern such as lead and arsenic. To aid evaluation of some specific regional areas of concern, geologic media were collected from bank deposits from three rivers impacted by mining and smelting, a roadbed built of smelter slag, and a quarry in which the rock contains naturally occurring arsenic. All media were sieved to provide particle size distributions. Whole media samples were evaluated for hand adherence using a dynamic handling procedure. Adherence tests employed six volunteers for each type of media under both wet and dry conditions. Median adherences of 7.8 and 0.66 mg/cm2 were observed across all media tested under wet and dry conditions, respectively. Sieve-separated fractions and handwash samples were analyzed by ICP-MS for Pb, As, Cd, Co, Cr, and Zn. Maximum Pb concentrations of 32,100 and 9,550 mg/kg were observed in a sieve-separated fraction and handwash residue sample, respectively. Distributions of particle fractions adhering to skin were estimated by maximum likelihood estimation.