Development of a novel method for estimating dermal contact with hand-applied cleaning solutions

Quantitatively characterizing dermal exposure for workers and consumers performing tasks with hand-applied cleaning solution is complex as many of the assessment variables are scenario specific. One of the key variables necessary for quantitatively estimating dermal exposure is the surface area of the hand contacted by the cleaning solution. However, no relevant data or methods are available in the literature. This study evaluated the feasibility of a novel simulation approach to measure skin contact area specific to hand cleaning with various types of liquid cleaning products to refine exposure and risk estimates for users of these products. This approach incorporates cotton rags wetted with pigmented cleaning solutions, volunteers wearing white cotton gloves during hand cleaning with those cotton rags, and digital imaging of the pigmented solution-contacted gloves post-simulation to quantify area of the hand contacted by the cleaning solution. When applied across three separate cleaning solutions, a denatured alcohol, an aqueous solution, and a lacquer thinner, this novel method performed well in estimating both palmer and dorsal surface areas of the hand contacted during simulated cleaning. The volume of cleaning solution applied to the rag and thickness of the rag were consistent predictors of contacted surface area. For the denatured alcohol, the time spent cleaning was additionally correlated with contacted surface area. This study suggests that this novel simulation approach could be an important tool for reducing an important source of uncertainty in dermal exposure assessments involving hand-applied cleaning solutions.