Abstract
Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash may pose health threats to onsite workers due to their inevitable dispersion in the working environments during recycling and disposal of fly ash from Municipal Solid Waste Incinerators (MSWIs). Here, PCDD/Fs in fly ash from an MSWI in Southern Taiwan was analyzed from several perspectives. The results can be summarized as follows: (1) Through multiple comparison analyses, it was revealed that four types of congeners (OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF) have significantly higher concentrations than other species (p < 0.01). (2) 2,3,4,7,8-PeCDF represented the main contributor to the total toxic equivalent concentration (TEQ). The top three candidate indicators of total TEQ are OCDF, 1,2,3,4,6,7,8-HpCDF and 2,3,4,7,8-PeCDF, in which OCDF might be most powerful indicator of fly ash from similar sources. (3) It was indicated that all congeners correlated positively with each other (with R2 values in the range between 0.707–0.939); Meanwhile, the results of the cluster analysis unveiled the specific features of several congeners (such as 1,2,3,7,8,9-HxCDF, OCDD and OCDF). (4) Through assessing health risk with a Monte Carlo simulation, both the 95th percentile carcinogenic risk (CR) and non-carcinogenic risk (non-CR) for onsite workers exceeded the threshold limit and should be considered as significant risks for onsite workers. (5) The results of the sensitivity analysis suggested that concentration (CC) and exposure duration (ED) were the two most sensitive parameters in both the CR and non-CR assessment. The above findings could be useful for improving existing health risk mitigation/management strategies for onsite workers in waste incineration plants.
Highlights
Within the generic terms of dioxins, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are a group of dangerous chemicals known as persistent organic pollutants (POPs)
The results can be summarized as follows: (1) Through multiple comparison analyses, it was revealed that four types of congeners (OCDD, OCDF, 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF) have significantly higher concentrations than other species (p < 0.01). (2) 2,3,4,7,8-PeCDF represented the main contributor to the total toxic equivalent concentration (TEQ)
(3) It was indicated that all congeners correlated positively with each other; the results of the cluster analysis unveiled the specific features of several congeners. (4) Through assessing health risk with a Monte Carlo simulation, both the 95th percentile carcinogenic risk (CR) and non-carcinogenic risk for onsite workers exceeded the threshold limit and should be considered as significant risks for onsite workers
Summary
Within the generic terms of dioxins, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are a group of dangerous chemicals known as persistent organic pollutants (POPs). Among the PCDD/F homologues, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is considered the most toxic form. Fly ashes from MSWIs have been classified as hazardous waste due to the enrichment of dioxins and other chemicals, onsite workers in MSWIs are inevitably exposed to fly ash, due to its dispersion in the working environment during recycling and disposal. More attention should be paid to health risk evaluations, strengthening of occupational protection, and reduction of exposure to PCDD/Fs in the case of onsite workers in MSWIs. fly ash has been classified as a hazardous waste based upon the pH, chemical components, and the particle size distribution of the ash (Tian et al, 2012). It is vital to determine the key exposure pathway, which will help in providing specific personal protection equipment for onsite workers
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