Composition profiles, monthly changes and health risk of PCDD/F in fly ash discharged from a municipal solid waste incinerator (MSWI) in Northeast China

Abstract

One of the hazardous wastes present in municipal solid waste incinerators (MSWI) is fly ash; it threatens the health of onsite workers due to its inevitable dispersion on the ground and in the atmosphere during the process of collecting, cleaning and transporting it from the incinerator. In the present study, composition profiles and monthly changes of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash from a MSWI in Northeast China were studied. In addition, the health risk posed by these chemicals to onsite workers was quantitatively assessed based on a Monte Carlo simulation. The total and toxic equivalent concentrations of PCDD/Fs (TPCDD/Fs and TEQ) in fly ash in the sampling months were 36.5–5653.0 ng g⁻¹ (with a median value of 823.5 ng g⁻¹) and 3.2–800.1 ng TEQ g⁻¹ (with a median value of 111.1 ng TEQ g⁻¹), respectively. Although the composition of the municipal solid waste did not vary over the sampling period, a wide variation of mass concentration of PCDD/Fs in the fly ash was observed. The 95th percentile carcinogenic risk (CR) and non-carcinogenic risk (non-CR) for onsite workers were much lower than the threshold values of 10⁻⁶ and 1.0, respectively, suggesting that the potential health risk was not significant. Accidental ingestion was the largest contributor to health risk for onsite workers, at 67.7% and 68.6% of the CR and non-CR, respectively. Filter-type gas masks could be effective personal protection equipment to ameliorate this risk; not only could they reduce potential exposure to contaminants via ingestion and inhalation, but also reduce exposure to contaminated soil and ambient air. These results could be useful for health risk management of onsite workers in MSWI plant.