Cancer and non-cancer risk associated with PM10-bound metals in subways

Non-cancer and cancer health risks to humans associated with respirable particulate matter ≤10 µm (PM₁₀) in an indoor microenvironment such as a subway cabin are currently a public concern. In this study, detailed investigations of human health risks due to PM₁₀-bound metals in a subway cabin were conducted for the first time. Cancer risks (CRs) were estimated for inhalation exposure (CR_inh) using a Monte Carlo probability density function and were compared with incremental lifetime CRs (ILCRs). Moreover, the percentage contributions of each metal to the risk levels were calculated to identify the elements potentially responsible for human health risks. The significant (>1) for non-CRs levels as HI (hazard index) was estimated for children and adults for all types of exposure (inhalation, ingestion, and dermal). Pb, Cr, and Ni were recognized as the foremost contributors to the HQ (hazard quotient) levels for all types of exposure. For subway commuters, the CR_inh and ILCR levels for adults were marginally higher than the satisfactory maximum point of confinement of the lifetime carcinogenic risk level (1 × 10⁻⁵) where as CR_inh for children was within the acceptable limit (1 × 10⁻⁶–1 × 10⁻⁵). Cr was identified as the predominant carcinogenic element, with 91% contribution to the total CR level in the subway cabin on the Seoul Metropolitan Subway.