Effect of residential air cleaning interventions on risk of cancer associated with indoor semi-volatile organic compounds: a comprehensive simulation study

Summary: Background: Human exposure to multiphase semi-volatile organic compounds (SVOCs) via multiple routes has been associated with health risks. Residential air cleaning interventions remove SVOCs adsorbed on airborne particles, which subsequently affects indoor concentrations of SVOCs in other phases. We aimed to investigate the effect of residential air cleaning interventions on the overall cancer risk associated with multiphase SVOCs. Methods: We simulated concentrations of eight multiphase SVOCs (including seven polycyclic aromatic hydrocarbons [PAHs] and di(2-ethylhexyl) phthalate [DEHP]) using a kinetic partition mass balance model for three exposure scenarios: naturally ventilated residences without intervention (scenario 1), naturally ventilated residences with portable air purifiers (scenario 2), and mechanically ventilated residences with air filtration units (scenario 3). We converted indoor concentrations of the individual PAHs into indoor concentrations of equivalent benzo[a]pyrene (BaPeq) using the BaP cancer potency equivalent factor for each PAH. We estimated indoor exposure to SVOCs via inhalation, dermal absorption, and ingestion. For each scenario, we calculated the incremental lifetime cancer risk (ILCR) associated with indoor exposure to each SVOC via the three routes and the total ILCR (all three routes combined). Findings: Mean total ILCRs associated with exposure to BaPeq were 4·42 × 10−6 (SD 2·84) for scenario 1, 2·36 × 10−6 (1·53) for scenario 2, and 4·88 × 10−6 (4·86) for scenario 3. Mean total ILCRs associated with exposure to DEHP were 3·61 × 10−6 (3·60) for scenario 1, 7·51 × 10−7 (5·34) for scenario 2, and 1·48 × 10−5 (2·02) for scenario 3. Ingestion of settled dust was the most important contributor to the total ILCR for both BaPeq and DEHP in all the studied scenarios. Interpretation: The large-scale use of mechanical ventilation systems in urban residences in China needs to be evaluated owing to their potential exacerbation of the cancer risks associated with common indoor SVOCs. Funding: National Key Project of the Ministry of Science and Technology and Natural Science Foundation of China