As primary anthropogenic emission source of toxic pollutants such as heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), municipal solid waste (MSW) incineration has caused worldwide concern. However, a comprehensive analysis of the pollution characteristics and health risks of PCDD/Fs and heavy metals in soils around MSW incineration plants is lacking. In this study, 17 PCDD/Fs and 11 heavy metals in soil samples collected near MSW incineration plants in Sichuan province were investigated to evaluate their pollution characteristics and potential health risk. Sichuan was selected as the study area because the MSW incineration amount in this province ranks first among all inland provinces in China. The PCDD/Fs concentrations ranged from 0.30 to 7.50 ng I-TEQ/kg, which were significantly below risk screening and intervention thresholds. Regarding heavy metals, principal component analysis suggested that Hg, Pb and Zn were the primary metals emitted from the MSW incineration plants. Cluster analysis of PCDD/Fs and heavy metals showed that of PCDD/Fs homologs and heavy metals (e.g., Hg, Pb, Zn and Cd) were clustered into one group, indicating the coexistence and coaccumulation of heavy metals (especially Hg, Pb, Zn, and Cd) and PCDD/Fs in soil. These heavy metals are thus candidate tracers for PCDD/Fs in soil near MSW incineration plants. A health risk analysis found that the carcinogenic and non-carcinogenic risks of PCDD/Fs and heavy metals (except for Ni) in the soil samples were all within acceptable levels. This study provides new insights into correlations and health risks of PCDD/Fs and heavy metals in surface soil near MSW incineration plants. The findings have implications for future studies of environmental and human health risk analysis related to waste incineration.

Experimental data on the contribution of a dump site in Tanzania as a point source of the 17 possible congeners of PCDD/Fs to the environment is presented. Dry and wet season samples were collected around Pugu municipal dump site followed by GCxGC-TOFMS analysis. The dominant congeners were OctaCDD, 1,2,3,4,6,7,8-HepCDF; 1,2,3,4,6,7,8-HeptaCDD and 1,2,4,7-PeCDD. The concentrations of the congeners expressed as TEQ WHO₂₀₀₅ ranged from 11.69 to 48.97 pg/g with a mean of 29.44 pg/g for the dry season and TEQ WHO₂₀₀₅ 4.13–85.82 pg/g with a mean of 41.51 pg/g for the wet season. These levels were speculated high enough to accumulate in free-range chickens and cause harmful effects to humans that consumed them especially residents around Pugu dump site. Exposure of people to PCDD/Fs through dermal absorption and soil ingestion were estimated using the VLIER-HUMAAN Mathematical model. Exposure through dermal absorption was estimated to be 1.2 × 10⁻⁴ and 9.8 × 10⁻⁶ ng TEQ/kg day for children and adults respectively while through soil ingestion via consumption of contaminated foods and other sources was 0.0045 and 0.27 ng TEQ/kg day for children and adults respectively. These values however were well below the WHO tolerable daily intake. Generally, there was no significant variation for total PCDD/Fs in the dry and wet season (α = 0.08). Strong positive correlation (r = 0.94) between total PCDD/Fs and organic matter content was observed during the wet season.

A typical two-day start-up of municipal solid waste incinerators (MSWIs) can yield polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) and polychlorinated biphenyl (PCB) emission quantities around 10 times higher than those from an entire year of normal operations, as measured in this study. Thus, we tested specific control strategies for inhibiting the formation of chlorinated persistent organic pollutants (Cl-POPs), namely, extensively cleaning the ash accumulated beneath the furnace bed of the combustion chamber and deposited on the walls of the superheater and economizer and shortening the residence time of the flue gas in the optimal temperature window for Cl-POP formation. Also, we advanced the injection times of the activated carbon and lime slurry to lower Cl-POP emissions during start-up. Our findings show that these strategies were highly effective and reduced the Cl-POP emissions by > 98%, most of which (96.4–98.2%) was attributable to inhibiting formation. In summary, the proposed control strategies require no modifications to existing air pollution control devices, have little influence on operational cost, and are effective and feasible for the majority of MSWIs.

Polychorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs) such as the non-ortho PCBs (nPCBs) persist in the environment despite international measures to ban their emissions. We determined congener patterns and temporal trends for PCDDs, PCDFs, nPCBs as well as their toxic equivalents (TEQs) in eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) sampled from Prince Leopold Island in the Canadian Arctic between 1975 and 2014. The dominant PCDD congeners were 1,2,3,7,8-PnCDD, 2,3,7,8-TCDD and 1,2,3,6,7,8-HxCDD, and the dominant PCDF congener was 2,3,4,7,8-PnCDF. The nPCB profile was dominated by PCB-126. The TEQ profile in the murre eggs was dominated by nPCB-TEQ whereas in the fulmar eggs, the PCDF-TEQ contribution to ΣTEQ was slightly greater than that of nPCB-TEQ. Concentrations of ΣPCDD, ΣPCDF, ΣnPCB and ΣTEQ declined between 1975 and 2014 in both murre and fulmar eggs. Based on TEQ thresholds in the literature for other species, and taking into account the trend towards declining TEQ levels, it is unlikely that current levels of PCDDs, PCDFs or nPCBs are affecting the reproductive success of thick-billed murres or northern fulmars in the Canadian Arctic.

Persistent organic pollutants (POPs), including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs), have been identified in penguins, lichens, soils, and ornithogenic soils in the Antarctic coastal environment in this study. To the best of our knowledge, no previous study has reported PBDD/F and PBB data from Antarctica. The POP mass contents in penguins were in the following order: PCBs >> PBDEs >> PCDD/Fs; PCBs were the dominant pollutants (6310–144,000 pg/g-lipid), with World Health Organization toxic equivalency values being 2–14 times higher than those of PCDD/Fs. Long-range atmospheric transport is the most primary route by which POPs travel to Antarctica; however, local sources, such as research activities and penguin colonies, also influence POP distribution in the local Antarctic environment. In penguins, the biomagnification factor (BMF) of PCBs was 61.3–3760, considerably higher than that for other POPs. According to BMF data in Adélie penguins, hydrophobic PBDE congeners were more biomagnified at log Kow > 6, and levels decreased at log Kow > 7.5 because larger molecular sizes inhibited transfer across cell membranes.

Anaerobic enrichment cultures derived from contaminated Kymijoki River sediments dechlorinated 1,2,3,4-tetrachlorodibenzofuran (1,2,3,4-tetra-CDF), octachlorodibenzofuran (octa-CDF) and 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-tetra-CDD). 1,2,3,4-tetra-CDF was dechlorinated via 1,2,3-, 2,3,4-, and 1,3,4/1,2,4-tri-CDFs to 1,3-, 2,3-, and 2,4-di-CDFs and finally to 4-mono-CDF. The dechlorination rate of 1,2,3,4-tetra-CDF was generally slower than that of 1,2,3,4-tetra-CDD. The rate and extent of 1,2,3,4-tetra-CDD dechlorination was enhanced by addition of pentachloronitrobenzene (PCNB) as a co-substrate. Dechlorination of spiked octa-CDF was observed with the production of hepta-, hexa-, penta- and tetra-CDFs over 6 months. Two major phylotypes of the Chloroflexi community showed an increase, one of which was identical to the Dehalococcoides mccartyi Pinellas subgroup. A set of twelve putative reductive dehalogenase (rdh) genes increased in abundance with addition of 1,2,3,4-tetra-CDF, 1,2,3,4-tetra-CDD and/or PCNB. This information will aid in understanding how indigenous microbial communities impact the fate of PCDFs and in developing strategies for bioremediation of PCDD/F contaminated sediments.

Air, soils and sediments surrounding an abandoned pentachlorophenol (PCP) factory were sampled to determine the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), unintentionally formed during PCP production. The mean concentration of PCDD/Fs in ambient air was one order of magnitude higher than that of the reference site. A trend of decreasing concentrations with increasing distance from the factory was observed, suggesting this site has a significant influence on the regional ambient air. As for soil samples collected within 3 km from the factory and sediment samples from the adjacent rivers, high levels of contamination were found with WHO-TEQ concentrations of 193 ± 211 pg/g and 667 ± 978 pg/g, respectively. The PCDD/F homologue profiles of all samples were consistent with those found in the technical product of PCP, with OCDD as the dominant congener. These results indicate PCDD/Fs in the historical contaminated site pose a long-term impact on surrounding environment.

This paper describes the first report of dioxins and furans (PCDDs/Fs) in sediment cores from Mexico. Sedimentation rates and vertical fluxes were estimated using ²¹⁰Pb dating. Two cores correspond to marine sediments and one to an endorheic lake. Concentrations of PCDDs/Fs found in the three sites are typical of non-impacted areas with low concentrations when compared to reference values. However the PCDDs/Fs sediment profiles show an increasing concentration trend in the upper core sections. This behavior is different from that found at many sites around the globe where diminishing concentrations have been reported. A strong predominance of OCDD was observed, and a comparison to typical composition profiles of industrial and other sources did not result in clear origin assignments for these measured compounds. We suggest that local sources may be responsible for the increase in concentration and, because these undetermined sources have not been curtailed, their importance is still growing.

The control of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from the flue gas in hazardous waste incinerators (HWIs) is an intractable problem. To figure out the formation mechanism of PCDD/Fs and reduce the emission, a field study was carried out in a full-scale HWI. Ca(OH)₂ & (NH₄)H₂PO₄ or CH₄N₂S & (NH₄)H₂PO₄ were injected into the quench tower, and the detailed inhibition effect on PCDD/Fs formation by the inhibitors coupled with quench tower was studied. Gas and ash samples were collected to analyze PCDD/Fs. XPS, EDS characterization and Principal component analysis were adopted to further analyze the de novo and precursors synthesis. The PCDD/Fs emissions reduced from 0.135 ng I-TEQ/Nm³ to 0.062 or 0.025 ng I-TEQ/Nm³ after the injection of Ca(OH)₂ & (NH₄)H₂PO₄ or CH₄N₂S & (NH₄)H₂PO₄, respectively. The quench tower was found mainly hindering de novo synthesis by reducing reaction time. CP-route was the dominant formation pathway of PCDD/Fs in quench tower ash. Ca(OH)₂ & (NH₄)H₂PO₄ effectively inhibit precursors synthesis and reduce proportions of organic chlorine from 4.11% to 2.86%. CH₄N₂S & (NH₄)H₂PO₄ show good control effects on both de novo and precursors synthesis by reducing chlorine content and inhibiting metal-catalysts. Sulfur-containing inhibitors can cooperate well with the quench tower to inhibit PCDD/Fs formation and will be effective to reduce dioxins formation in high chlorine flue gas. The results pave the way for further industrial application of inhibition to reduce PCDD/Fs emissions in the HWIs flue gas.

Studies on the human body burden of dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in populations around municipal solid waste incinerators (MSWIs) in China are limited. The objective of this study was to assess the potential adverse health effects of an 8-year MSWI on the surrounding population and identify possible exposure pathways. We hypothesized that the MSWI would result in different environmental impacts and population health outcomes between upwind and downwind of its 3 km vicinity. We conducted a 10-year retrospective mortality survey on the population surrounding the MSWI. Then, we selected 50 residents aged 50 years or older on each of the upwind and downwind sides of MSWI to test serum PCDD/Fs. Meanwhile, environmental and food exposures to PCDD/Fs were tested for selected residents. The age-adjusted mortality rates were significantly higher for residents downwind than upwind, but no significant difference was found in the standardized mortality ratio before and after the MSWI operation. The toxic equivalents (TEQ) and major congeners of PCDD/Fs were significantly higher in the sera of the downwind residents than in the upwind. The PCDD/Fs in air, soil, dust, and vegetables on the downwind side were not significantly different from those on the upwind side, but the mean concentrations of PCDD/Fs in downwind hen eggs was significantly higher than those from upwind. In conclusion, downwind residents living within 3 km of the MSWI had higher age-adjusted mortality and serum level of PCDD/Fs than upwind residents. This higher mortality rate among downwind residents was not associated with MSWI. However, the higher levels of PCDD/Fs in downwind hen eggs suggest that the downwind population dioxin exposure was related to their location.