Hands as Agents of Chemical Transport in the Indoor Environment

Indoor environments are important sources of exposure to chemicals intentionally added to consumer products, building materials, etc. Previous work has shown that semivolatile organic compounds (SVOCs) migrate from product/material sources to partition to indoor surfaces, including skin and hands, and that SVOCs on hands reasonably indicate nondietary exposure to indoor SVOCs. We hypothesize that the hands of indoor occupants, which contact numerous products and surfaces, transport SVOCs in the indoor environment to an extent comparable to that of fugacity-driven and advective transport. This process of "hand-based" chemical transport is analogous to that of fomite transmission of pathogens. We explore this hypothesis using a data set of halogenated flame retardants, organophosphate esters, and phthalate esters in indoor air, floor dust, and wipes of hands and surfaces of electronic devices of 51 participants. Cluster analysis shows the similarity of the SVOC profiles on all participants' hands relative to those of all device surfaces, demonstrating the ubiquity of these SVOCs. Network analysis consistently shows the centrality of hands, followed by air, dust, and laptops, indicating that hands are most correlated with all sample types. The significance of this hypothesis lies in the ability of hands to rapidly transfer SVOCs among surfaces indoors, with implications for exposure.