A Comparison of Surface Sampling Techniques for Semi-Volatile Organic Substances in an Electronics Recycling Facility

Consumer products and building materials contain large numbers of semi-volatile organic compounds (SVOCs), which are consequently routinely detectable in indoor air and dust and in surface wipe samples. Biomarkers of SVOC exposure are commonly found in human blood and urine, and exposures implied by observed biomarker levels often cannot be explained by dietary ingestion and/or inhalation. The apparent missing dose is most likely explained by non-dietary ingestion and/or dermal absorption. However, translation of surface loads to dose remains challenging. Recent studies have determined the presence of an organic layer on indoor surfaces that can serve as a reservoir for SVOCs. Whether SVOCs on surfaces are primarily bound to particulate matter or are dissolved in an oily film might reasonably be expected to influence the mechanism(s) by which humans are exposed to them. The objective of this study is to compare surface sampling by vacuum and solvent-moistened wipes to assess the potential magnitude of the non-particle bound reservoir. Toward that end, an electronic waste recycling facility was selected as a target-rich environment for SVOC surface sampling. Collocated vacuum and wipe samples were collected and analyzed for selected SVOCs including flame retardants and phthalates. The results failed to consistently find higher surface loads by wipe than by vacuum, which may have been attributable to high SVOC loads and limitations of chemical analyses. Therefore, additional testing was performed to further evaluate both sample collection methods and sample extraction efficiencies. Some of the key findings from the post-hoc sampling round provided insight regarding the recommended number of sequential wipes and extractions and preferred extraction method for highly contaminated surfaces.