Abstracts: ISEE 22nd Annual Conference, Seoul, Korea, 28 August-1 September 2010: Exposure Assessment by Various Media and Pathways
Individuals encounter a wide range of pollutants indoors, and semivolatile organic compounds (SVOCs), which are found both in the gas and condensed phase, are of particular interest because they can be redistributed over time from their original source to indoor air, dust, and surfaces.
As part of the Northern California Household Exposure Study, house dust and indoor air samples were collected in 50 homes: 40 homes in Richmond, CA, and 10 homes in Bolinas, CA. Dust samples were analyzed for 79 SVOCs, and air samples were analyzed for 106 SVOCs and particulate matter (PM2.5). Seventy-six SVOCs were analyzed in both air and dust, including 24 polycyclic aromatic hydrocarbons, 3 polychlorinated biphenyls, 2 polybrominated diphenyl ethers (PBDEs), 36 pesticides, and 11 phthalates.
Overall, we detected 58 target analytes in house dust above method reporting limits. Phthalates and flame retardants were generally detected at the highest concentrations; DEHP, BBP, PBDE 99, PBDE 47, DBP were the 5 chemicals with the highest concentrations at the 95th percentile. Empirical data were used to explore theoretical partitioning relationships between air and dust in a manner similar to recent work by Weschler and Nazaroff. Specifically, gas-phase only concentrations were estimated from total air (particulate and gas phase) concentrations, assuming equilibrium and using residence-specific particulate concentrations. Correlation analyses for gas-phase air and dust concentrations revealed significant associations for several phthalates, pesticides, and PBDE 47. Gas-phase air concentrations, fraction of organic matter, octanol-air partition coefficient, and dust density were used to predict dust concentrations, which were compared with measured values using regression models (R2∼0.7). Sensitivity analyses were conducted to evaluate the influence of assumed parameter values.
Understanding partitioning relationships between air and dust will advance our understanding of exposure pathways in the indoor environment, and can be used to prioritize exposure measures in large-scale epidemiological studies.