Optimization of cancer risk assessment model for PM2.5-bound PAHs Application in Shanxi of China SM

To optimize the models for cancer risk assessment of PM2.5-bound
polycyclic aromatic hydrocarbons (PAHs), six models of three types
utilized with high frequency in recent years, including the USEPA
recommendation (Model I), inhalation carcinogen unit risk (Models
IIA–IID), and three exposure pathways (inhalation, dermal, and oral)
(Model III), were selected to calculate potential cancer risk using the
benzo[a]pyrene toxicity equivalent method. The results indicated no
significant differences in the risk values between Models IIA and III, and
no significant differences were found among Models IIB, IIC, and IID.
However, there were significant differences between Models I and II, and
between Models I and III. Furthermore, the optimization of Model I
indicated that the population exposure parameters for each country should
be used and age differences should not be disregarded. However, no
significant differences were observed with respect to gender. In
conclusion, Model I was superior to the other models; when age differences
were not considered, Model IID (the USEPA's integrated risk
information system) was preferred to replace Models IIB and IIC. Models
IIA and III may overestimate the risk of carcinogens, and their parameters
need to be reoptimized to accurately assess cancer risks.