Spatiotemporal distribution characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans in PM_2.5 in Pudong of Shanghai and population health assessment

Background In the Global Burden of Disease research, it has been found that atmospheric fine particulate matter (PM_2.5) pollution significantly harms human health. Currently, there is limited research on polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) that exhibit high toxicity effects in PM_2.5 .

Objective By studying the spatiotemporal distribution and variation characteristics of PCDD/Fs in PM_2.5 in Pudong area of Shanghai, to assess the associated population health risk.

Methods This study set up 28 sampling points in Pudong area. One sample of PM_2.5 was collected during winter (February 2022) and summer (July 2022) at each site, with a sampling period lasting 24 h. The concentration of PM_2.5 was measured by membrane filter method, and the content of 17 kinds of 2,3,7,8-substituted chlorinated PCDD/Fs in the samples was analyzed using isotope dilution. Seasonal variations (winter and summer) in the concentrations of PM_2.5 and PCDD/Fs were evaluated, sources of PCDD/Fs pollution were tracing by principal component analysis, and health risks to the population from respiratory exposure to PCDD/Fs were estimated by VLIER-HUMAAN model.

Results The PM_2.5 concentrations in the 28 samples ranged from 10 to 126 μg·m⁻³, while the concentrations of PCDD/Fs in PM_2.5 ranged from 58 to 2625 fg·m⁻³. The concentration of PM_2.5 during winter (11-126 μg·m⁻³) was higher than that during summer (10-60 μg·m⁻³). The concentration range of PCDD/Fs in winter was from 58 to 2625 fg·m⁻³, which corresponded to a range of toxic equivalent quantity (WHO-TEQ) concentration from 2.99 to 40.97 fg·m⁻³ when taking World Health Organization's toxic equivalency factor (WHO-TEQ); the concentration range of PCDD/Fs in summer was from 72 to 446 fg·m⁻³, which corresponded to a range of WHO-TEQ concentration from 2.66 to 16.61 fg·m⁻³. This range in summer was significantly lower than that observed in winter. The results of principal component analysis revealed that waste incineration was the primary source of PCDD/Fs in winter PM_2.5 in the area, whereas traffic emissions emerged as the main source in summer. The assessment of Pudong residents' respiratory exposure to PCDD/Fs in PM_2.5 showed significantly higher exposure of children in summer and winter than that of adults, indicating higher susceptibility of children to air pollutants. Both the hazard ratios (HR) for children and adults were below 1, while the cancer risks (CR) ranged from 8.41×10⁻⁸ to 2.35×10⁻⁶. Notably, during winter, the CR at 4 locations slightly exceeds 1×10⁻⁶, indicating a potential carcinogenic risk.

Conclusion The overall pollution level of PCDD/Fs in PM_2.5 in Pudong area is relatively low, but it shows clear seasonal patterns. Waste incineration and traffic are the main sources of PCDD/Fs in PM_2.5 in the area. Although the cancer risk of exposure to PCDD/Fs in PM_2.5 for children or adults is relatively low, there is a certain risk at some locations in winter, necessitating additional monitoring and control.