PCDDs), Dibenzofurans Research Articles

Placental docosahexaenoic and arachidonic acids correlate weakly with placental polychlorinated dibenzofurans (PCDF) and are uncorrelated with polychlorinated dibenzo-p-dioxins (PCDD) or polychlorinated biphenyls (PCB) at delivery: A pilot study

Long chain polyunsaturated fatty acids (LC-PUFA), ARA (arachidonic acid, 20:4n−6) and DHA (docosahexaenoic acid, 22:6n−3) have positive effects and environment pollutants, polychlorinated dibenzo-p-dioxins/dibenzofurans(PCDD/F) and polychlorinated biphenyls (PCB) have negative effects on neural development during early life. Placental dioxin/PCB serves as markers for cumulative exposure to fetus. Fatty acid composition of placenta depends on nutrient supply during pregnancy, serving as indicators for fetal ARA and DHA accretion. This study investigated correlation between placental PCDD/F and PCB toxic equivalent (TEQ) and LC-PUFA in 34 pregnant women from Taiwan. Placental PCDF TEQ were inversely correlated with placental ARA (p=0.020), C20:3n−6 (p=0.01), C22:4n−6 (p=0.04), C22:5n−6 (p<0.01) and with DHA (p=0.03), but ARA and DHA did not vary with PCDD, dioxin-like and indicator PCB. After adjustment for age and body mass index, a one-unit PCDF TEQ increase was associated with 1.021%w/w and 0.312%w/w decreases in ARA (β=−1.021, p=0.03) and DHA (β=−0.312, p=0.03). Since ARA and DHA were unrelated to three classes of toxins, and a weak negative association was found with PCDF, these data provide no basis for discouraging marine fish consumption during pregnancy for Taiwan women on the basis of these organics. Pregnant women should consume fish for its unique package of nutrients while avoiding few species with high organic pollutant or mercury contamination.

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in soils of Moscow

The contents of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) in the soils of Moscow were estimated. The concentrations of PCDDs and PCDFs mainly vary in the range of 0.27–16.1 ng WHO-TEQ/kg with single points of very high contamination up to 57.3 ng WHO-TEQ/kg; the concentrations of PCBs are in the range of 2.1–50.8 ng/g with sites of high contamination up to 4020 ng/g. The contribution of dioxin-like PCBs to the total dioxin toxic equivalent is very high: from 16 to 85%. The high levels of PCDDs and PCDFs in the soils indicate the strong contamination of the atmospheric air. The main source of these compounds is apparently motor transport.

Formation of polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) from a refinery process for zinc oxide used in feed additives: A source of dioxin contamination in Chilean pork

The Republic of Korea found dioxin at concentrations exceeding the Korean maximum residue limit (MRL) in pork (2 pg TEQ g −1 fat) imported from Chile in June 2008. Korea and Chile collaborated and investigated to find out the sources of contamination. An isotope dilution method and high resolution gas chromatography/mass spectrometry (HR–GC/MS) were used for the analysis of PCDD/Fs. PCDD/Fs were found from 2.17 to 36.7 pg TEQ g −1 fat from Chilean pork. 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, and 2,3,4,6,7,8-HxCDF were found as the major congeners in pork samples. 2,3,4,7,8-PeCDF showed the highest concentration and contributed about 30% among the congeners in most of the samples. 2,3,7,8-TCDD, 1,2,3,7,8,9-HxCDD, OCDD, 2,3,7,8-TCDF, 1,2,3,7,8-PeCDF, 1,2,3,7,8,9-HxCDF, and OCDF were not detected or exist at background levels in the less contaminated samples. Remarkably high concentrations of PCDD/Fs were found in samples of zinc oxide (17 147 pg TEQ g −1), zinc oxide based premix (6673 pg TEQ g −1), and the residue crust (800 pg TEQ g −1) in a mixing chamber in the feed mill. From the results of various investigations, this case concluded that zinc oxide in the feed was the major source of the dioxin contamination in pork. The dioxins were formed from a metal refinery process to collect zinc oxide.

Role of black carbon in the distribution of polychlorinated dibenzo- p-dioxins/dibenzofurans in aged field-contaminated soils

Floodplain soils containing elevated levels of polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) were collected from several locations along the Tittabawassee River (Michigan, USA). The PCDD/F profiles of these soils exhibited distinct congener patterns consistent with byproducts from either chloralkali manufacturing or chlorophenols productions. Black carbon (BC) particles were isolated for the first time from floodplain soil impacted by PCDD/Fs. Petrographic analysis showed that BC particles, including coal, oxidized coal, metallurgical coke, depositional carbon, coal tar/pitch, cenosphere, and charcoal, comprised approximately 30% by volume of the organic fraction with size range of 250 μm–2000 μm from a typical floodplain soil. The BC particles with anthropogenic origin such as pitch and coke associated with the chloralkali production process served as both the source and subsequent transporter for the highly hydrophobic PCDD/Fs. These anthropogenic BC particles were enriched with high levels of PCDFs, containing approximately 1000-fold the concentration found in the bulk soil. The strong association of PCDD/Fs with anthropogenic BC directly impacts the physicochemical and biological availability thus the risk associated with these hydrophobic organochlorines in soils and sediments.

Analysis of Dioxins by Gas Chromatography/Resonance-Enhanced Multiphoton Ionization/Mass Spectrometry Using Nanosecond and Picosecond Lasers

Dioxins in a soil sample were measured using gas chromatography/resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry coupled with different types of laser sources. The fourth-harmonic emission (266 nm) of a nanosecond Nd:YAG laser (1 ns) provided low ionization efficiency, especially for highly chlorinated dioxins/dibenzofurans (CDDs/CDFs). The ionization efficiency was improved using the fourth-harmonic emission (266 nm) of a picosecond Nd:YAG laser (4 ps), due to shorter singlet excited-state lifetimes. It was, however, difficult to efficiently ionize hepta-CDD and octa-CDD/CDF, because of their shorter lifetimes, which were induced by stronger spin-orbit coupling that led to efficient relaxation of the excited molecule to triplet levels. The ionization efficiency was substantially improved using the fifth-harmonic emission (213 nm) of the picosecond Nd:YAG laser (4 ps), in which the analyte molecule that was relaxed to triplet levels was efficiently ionized using a photon with sufficient energy for ionization, although the pulse energy obtained at 213 nm was only one-third of the pulse energy obtained at 266 nm. The limits of detection achieved for 17 toxic polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) were 0.41-45 pg. The analytical instrument developed in the present study performed sufficiently well for the practical trace analysis of dioxins in soil samples.

Polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in Finnish semi-domesticated reindeer ( Rangifer tarandus tarandus L .)

To explore the concentrations and dynamics of polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Finnish semi-domesticated reindeer ( Rangifer tarandus tarandus L.) the reindeer milk and tissue samples were collected from the sub-arctic northern Finland. Reindeer milk's PCB sum (1.20 ng g − 1 wet weight) and PCDD/F sum (0.70 pg g −1 ww) in autumn were higher than in summer (PCBs 0.50 ng g − 1 ww and PCDD/Fs 0.20 pg g − 1 ww). The mean fat content in autumn milk (26%) was significantly higher than in summer (10%). Concentrations in reindeer milk were generally far below 50% of that in adult reindeer body burden. However, the bioaccumulation factors were multiple in milk/reindeer calf ratio and that aroused the question of other important exposure routes than lactation. The muscle and liver of reindeer calves had higher PCDD/F and PCB concentrations than adult animals that possibly indicate the significance of transfer of these compounds from dam to calf through lactation and placenta. However, PBDE concentrations were higher in adult reindeer, especially in liver. In addition, reindeer liver seems to have a special feature to collect highly toxic PCDD/Fs, although the PCB sum concentrations (range from 0.33 to 1.69 ng g − 1 wet weight) were clearly higher than the sums of PCDD/Fs (range from 3.78 to 39.2 pg g − 1 ww). Stillborn reindeer calves represented individuals who had got their PCDD/F, PCB and PBDE load only via the placenta. Concentrations in muscle and brown adipose tissue samples did not indicate dependency on fat content. Obviously effective placental transfer of PCBs and PBDEs from reindeer dam to foetus was seen in this study.

A new alternative paraffinic–palmbiodiesel fuel for reducing polychlorinated dibenzo-p-dioxin/dibenzofuran emissions from heavy-duty diesel engines

Polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) emissions from heavy-duty diesel engines (HDDEs) fuelled with paraffinic–palmbiodiesel blends have been rarely addressed in the literature. A high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) was used to analyze 17 PCDD/F species. Experimental results indicate that the main species of PCDD/Fs were OCDD (octachlorinated debenzo-p-dioxin) and OCDF (octachlorodibenzofuran), and they accounted for 40–50% of the total PCDD/Fs for all test fuels. Paraffinic–palmbiodiesel blends decreased PCDD/Fs by 86.1–88.9%, toxic PCDD/Fs by 91.9–93.0%, THC (total hydrocarbons) by 13.6–23.3%, CO (carbon monoxide) by 27.2–28.3%, and PM (particulate matter) by 21.3–34.2%. Using biodiesel blends, particularly BP9505 or BP8020, instead of premium diesel fuel (PDF) significantly reduced emissions of both PCDD/Fs and traditional pollutants. Using BP9505 (95 vol% paraffinic fuel + 5 vol% palmbiodiesel) and BP8020 instead of PDF can decrease PCDD/F emissions by 5.93 and 5.99 g I-TEQ year −1 in Taiwan, respectively.

Persistent organic pollutants in two Finnish watercourses: Levels, congener profiles and source estimation by mussel incubation

Mussel incubation was used to compare two Finnish watercourses, which have been contaminated by effluents from pulp mills and are known to be polluted with polychlorinated biphenyls (PCBs). Lake mussels ( Anodonta Piscinalis) incubated in 1998 and 2004 in the rivers Kymijoki and Vuoksi were analysed for PCBs and polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), diphenyl ethers (PCDEs), hydroxy diphenyl ethers (HO-PCDEs), methoxy diphenyl ethers (MeO-PCDEs), and polybrominated diphenyl ethers (PBDEs). The contamination of the River Kymijoki, which descends to the Baltic Sea, proved significantly greater than that of the River Vuoksi, with no decreasing apparent trend, except for the PBDEs. The River Vuoksi represented more a background area compared to the River Kymijoki, excluding the PCBs. The concentration of the PCDD/PCDFs in the Kymijoki mussels exceeded the EU’s maximum permissible level for PCDD/PCDFs in foodstuffs (4 pg g −1 fresh weight). Analyses of perfluorooctanesulphonate and perfluorooctanoate in the mussels incubated in 2005 and 2006 in the River Kymijoki revealed no significant contamination of the river with these compounds. Comparison of the data of the mussels with that of sediments and commercial formulations showed that the past manufacture of a chlorophenol-based wood preservative has remained a significant source of the PCDD/PCDFs, HO-PCDEs and PCDEs in the River Kymijoki. PCB formulations are believed to represent the major sources of the PCBs and PCNs in both watercourses, though situation in the River Kymijoki had been influenced by a chlor-alkali plant. Municipal wastewaters are believed to represent the major source of the PBDEs.

Spatial and temporal variation of polychlorinated biphenyls in the Houston Ship Channel

An on-going study in the Houston Ship Channel (HSC) characterized polychlorinated biphenyl (PCB) levels in sediment, water, and tissue in 2002–2003 and 2008. The observed PCB concentration ranges in all media were higher than those measured in other PCB-impacted water bodies in the world, with the highest concentrations occurring within the industrialized segments. Contrary to polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) observations, the PCB concentrations in the dissolved phase were greater than the suspended phase. Possible explanations include passage of colloids, competition for adsorption sites from other hydrophobic contaminants, and continuing current sources. The PCB homologue distributions were similar for suspended water, sediment and tissue with the profile normalized around penta-chlorobiphenyls, while the dissolved phase profile normalized around tri-chlorobiphenyls. PCB-209 was detected in the suspended water phase and in sediment (10%) prompting interest into its sources to the HSC since PCB-209 was present only in rare commercial mixtures and is a byproduct in very few manufacturing processes. Inter-media analyses showed a significant correlation and transfer of PCBs. Dioxin-like PCBs contributed significant toxicity to total equivalent in tissue (33%), while they were insignificant in water (<10%) and sediment (<5%). The PCB concentrations over time showed a significant decrease in suspended water, sediment and tissue, while dissolved water concentrations showed insignificant change. The homolog distribution, however, showed a significant change in dissolved water and fish, a minor change in sediment and insignificant change in suspended water. Furthermore, an analysis for six representative congeners showed that they were accurate in predicting the total PCB concentrations and could be thus used as indicator PCBs.

Impacts of dust storms on PCDD/Fs and regulated harmful matter in a basin area

Few studies have been conducted on the relationship between the high levels of dust particles and the concentrations of atmospheric PCDD/F during dust storm episodes. However, they did not investigate the impact of dust storm on basin areas. This present study shows the dust storm effect on regulated harmful matter and polychlorinated dibenzo- p-dioxin/dibenzofuran (PCDD/F) concentrations in basin areas. The results indicate that the average PM 10 (aerodynamic diameter less than 10 μm), SO 2 (sulfur dioxide), NO 2 (nitrogen oxides), CO (carbon monoxide) and O 3 (ozone) levels during the dust storm were 5.14, 2.30, 1.44, 1.40 and 1.41 times higher than those before the dust storm, respectively. Mean PCDD/F concentrations during the dust storm (0.958 pg Nm − 3; 0.0484 pg I-TEQ Nm − 3) were significantly higher than those before the dust storm (0.240 pg Nm − 3; 0.00705 pg I-TEQ Nm − 3). The PCDDs concentration during the dust storm was 1.84 times larger than that before the dust storm, and the PCDFs concentration was 10.2 times larger. Therefore, the dominant contribution of PCDD/Fs concentration during dust storm in the basin areas of northern Taiwan is PCDFs. OCDD concentration measured before dust storm was the highest among the seventeen investigated PCDD/F congeners, accounting for about 64.6% of the total concentration. However, OCDD concentration measured during the dust storm was comparable with the OCDF among the seventeen investigated PCDD/F congeners, accounting for about 24.5% (OCDD) and 22.9% (OCDF) of the total concentration. The above results indicate that the impact of a dust storm on regulated harmful matter and PCDD/F concentrations in the basin area is significant. An investigation of the health risk from dust storms in basin areas is needed.

Dioxin transfer from sediment to the infaunal surface deposit-feeding polychaete Perinereis nuntia in a laboratory-rearing experiment

In the presented study a laboratory experiment was conducted to investigate the transfer of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) from environmentally contaminated marine sediment to an infaunal surface deposit-feeding polychaete, Perinereis nuntia. Polychaetes were exposed to contaminated sediment for 42 d, and elimination of these compounds was studied for an additional 28 d. The sediment uptake rate coefficients (ks), elimination rate constants (k2), and the biota-sediment accumulation factors (BSAFs) were determined for PCDDs, PCDFs (PCDD/Fs), and dioxin-like PCBs. Each of these compounds was transferred from sediment to polychaete except for hepta- and octachlorinated PCDD/Fs. The BSAFs for dioxin-like PCBs (0.13-2.2) were significantly higher than those for PCDD/Fs (0.00022-0.36). The BSAF, ks, and k2 values obtained in the present study indicate that the bioaccumulation characteristics of PCDD/Fs in polychaete are similar to those in fish, and depend on their physical and chemical properties such as hydrophobicity and size of molecules. The ks values for PCDD/Fs and dioxin-like PCBs declined with an increase in their log KOW values, indicating a decrease in bioavailability. The negative exponential relationships of k2 versus KOW were observed for these compounds. The slope for the log-normalized regression of k2 versus KOW for the PCDD/Fs was smaller than that for the dioxin-like PCBs and that of ks versus KOW for the PCDD/Fs. Therefore, the negative exponential relationship of BSAF versus KOW was observed for PCDD/Fs, but not for dioxin-like PCBs.

Bioaccumulation of polychlorinated dibenzo- p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in fishes from the Tittabawassee and Saginaw Rivers, Michigan, USA

Characterizing biological factors associated with species-specific accumulation of contaminants is one of the major focuses in ecotoxicology and environmental chemistry studies. In this study, polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), and non- and mono- ortho-substituted polychlorinated biphenyl (PCB) congeners were analyzed in various fish species from the Tittabawassee and Saginaw Rivers (12 fish species; n = 314 individuals), Michigan, USA. Due to their migratory habits, greater δ 13C stable isotope values were found in walleye and white sucker among 12 fish species. Meanwhile, the δ 15N values indicated that the trophic status was least in carp and greatest in largemouth bass. The greatest total concentrations of dioxins were found in fishes with the lowest trophic status (carp ( n = 50) followed by channel catfish ( n = 49)), and concentrations of ΣPCDD/Fs (20–440 pg/g ww (wet weight)), ΣPCBs (16–690 ng/g ww), and TEQs (6.8–350 pg/g ww) in carp were also greater than the least mean concentrations in other fishes. Contributions of various biological factors to the species accumulation were assessed. Body weight and lipid content were found to be the most significant factors influencing accumulation of ΣPCDD/Fs. Lipid content and trophic level seemed to be dominant factors determining accumulation of ΣPCB and TEQs, but negative correlations between trophic status and concentrations of ΣPCBs and TEQs were observed possibly due to the great concentrations in benthivorous fishes such as carp occupying lower trophic levels. These factors can be used to predict the contaminant levels of dioxins and health risks of the fishes in the river ecosystem.

Contamination levels and congener distribution of PCDDs, PCDFs and dioxin-like PCBs in buffalo’s milk from Caserta province (Italy)

An extraordinary plan of official control was carried out in 2008 in Campania (Italy) with the aim to monitor polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) levels in buffalo milk and to detect the contaminated farms, most of which are located in Caserta province. For these companies has been ordered seizure and execution of additional analyses has been requested in farms falling in the nearness, within a distance of 3 km, for a total of 304 farms examined. Moreover, all non-compliant farms were subjected to a periodic sampling in order to monitor trends in the levels of contamination. In this paper the distribution and the concentrations of 17 PCDD/Fs and 12 dioxin-like PCBs in 460 samples of buffalo milk collected in the province of Caserta (Italy) are presented. The range of WHO-TEQ values for the PCDD/Fs in milk was 0.17 pg TEQ g −1 fat and 87.0 pg TEQ g −1 fat with a mean value 3.63 pg TEQ g −1 fat and medium value 2.25 pg TEQ g −1 fat. The concentrations of dioxin-like PCBs in the analysed samples ranged from 0.21 pg TEQ g −1 fat to 15.9 pg TEQ g −1 fat and the WHO-TEQ values of sum of PCDDs, PCDFs and dl-PCBs ranged from 0.45 pg TEQ g −1 fat to 103.0 pg TEQ g −1 fat. The geo-referencing analysis allowed to individuate a restricted area of the region object of the present study where is located the majority of the non-compliant farms. The study of the congeners distribution has finally suggested that the likely cause of contamination is to be attributed to the illegal burning of waste.

Inhibition of de novo synthesis of PCDD/Fs by SO 2 in a model system

The effect of sulfur dioxide (SO 2) on de novo synthesis of polychlorinated dibenzo- p-dioxins, dibenzofurans (PCDD/F) and biphenyls (PCB) was investigated in model systems containing carbon, activated by cupric chloride (CuCl 2). Five types of carbons (activated carbon, three types of carbon blacks, and graphite) were used to test the universal character of our results. The influence of SO 2 on speciation and behavior of copper compounds, catalytic oxidation of carbons, and formation of organic chlorine (extractable organic chlorine and non-extractable organic chlorine) was also studied to investigate the inhibition mechanism of SO 2 on de novo synthesis. It was found that SO 2 can sulfate CuCl 2, but does not react with CuO and CuCl 2·CuO in a 10% O 2/N 2 atmosphere at 300 °C. The suppression by SO 2 of organic chlorine (C–Cl) formation also confirmed these findings. It was also found that catalytic oxidation of carbons was strongly suppressed by SO 2. A dramatic decrease in PCDD/Fs formation was observed for all five carbons, while adding SO 2; at the same time the average chlorination level also decreased. However, the inhibiting effect on PCB was less apparent compared with that on PCDD/F. On the basis of the experimental results, the conversion of both cupric and cuprous chloride into the non-reactive sulfate was proposed as inhibition mechanism.

Atmospheric Emission of PCDD/Fs, PCBs, Hexachlorobenzene, and Pentachlorobenzene from the Coking Industry

The coking process is considered to be a potential source of unintentionally produced persistent organic pollutants (UP-POPs). However, intensive studies on the emission of UP-POPs from the coking industry are still very scarce. Emission of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), hexachlorobenzene (HxCBz), and pentachlorobenzene (PeCBz) covered under the Stockholm Convention were investigated for the coking process in this study. Stack gases from some typical coke plants in China were collected and analyzed to estimate the emission of UP-POPs from the coking industry. Emission factors of 28.9 ng WHO-TEQ tonne(-1) for PCDD/Fs, 1.7 ng WHO-TEQ tonne(-1) for dl-PCBs, 596 ng tonne(-1) for HxCBz, and 680 ng tonne(-1) for PeCBz were derived based on the investigated data. The annual emissions from the global coking industry were estimated to be 15.8 g WHO-TEQ for PCDD/Fs, 0.93 g WHO-TEQ for dl-PCBs, 333 g for HxCBz, and 379 g for PeCBz, respectively (reference year 2007). According to the distribution of PCDD/Fs, we argued for the de novo synthesis to be the major pathway of PCDD/F formation. With regard to the characteristics of dl-PCBs, the most abundant congener was CB-118, and the most dominant contributor to the total WHO-TEQ of dl-PCBs was CB-126.

Rapid transformation of 1,2,3,4-TCDD by Pd/Fe catalysts

This study investigated reductive dechlorination of 1,2,3,4-tetrachlorodibenzo- p-dioxin (1,2,3,4-TCDD) in the presence of Pd/Fe, Cu/Fe and Ni/Fe bimetallic catalysts or zero-valent iron (ZVI) under aqueous and ambient temperature conditions. It was found that the Pd/Fe catalyst can rapidly transform 1,2,3,4-TCDD to chlorine-free dibenzo- p-dioxin (DD) with >95% of conversion and half lives on the order of 5 h, whereas Cu/Fe, Ni/Fe and ZVI were not reactive over 10 d. The dechlorination of 1,2,3,4-TCDD in the Pd/Fe systems was found to be stepwise, with 1,2,3-tri (TrCDD), 1,2-di (DCDD), and mono-(MCDD) chlorodibenzo- p-dioxins as the three intermediate products at low concentrations and DD as the final and dominant product. The reaction rate of 1,2,3,4-TCDD dechlorination appeared to decrease as the coverage of palladium on iron particle surface increases from 0.0060 mol% to 0.0228 mol%. Compared to our prior study of reductive dechlorination of 1,2,3,4-TCDD with zero valent zinc (ZVZ) as the reductant, the reactions with Pd/Fe bimetallic materials were relatively slower for TCDD, but much faster for TrCDDs and DCDDs, yielding DD as the major product. The study suggested that Pd/Fe bimetallic catalyst-based reactions may be suitable for rapid decontamination of polychlorinated dibenzo- p-dioxin/dibenzofuran (PCDD/F) polluted soils and sediments.

Characterization of PCDD/Fs, PAHs, and heavy metals in a secondary aluminum smelter

This study characterizes polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polycyclic aromatic hydrocarbons (PAHs), and heavy metal concentrations in stack flue gas, workplace air, fly ash, bottom ash, and ambient air of a secondary aluminum smelter. The total PAH concentration in workplace air was dominated by 2- and 3-ring PAHs, accounting for 86.2% of the gas phase in the total PAHs. The PCDD/F concentrations in workplace air are 1–7 fold higher than that in ambient air. The mass distribution ratio for total PCDD/Fs was soil > ash > workplace air > ambient air > flue gas. Aluminum and Zn had the highest concentrations. A positive correlation existed between PCDD/Fs and PAHs concentrations (r2 = 0.920). The operation of secondary aluminum smelter affects the pollutant concentrations and surrounding air quality. Experimental results suggest that besides the terminal control technologies for stack flue gases, engineering control technologies in the workplace need further improvement.

Evaluation of daily intake of PCDD/Fs and indicator PCBs in formula-fed Spanish children

Human exposure to polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) occurs predominantly via food intake. In this study, the exposure assessment of these contaminants has been estimated for infant formula-fed children up to 1 year of age. PCDD/F concentrations in the infant formulae was low, ranging between 0.09 and 0.17 pg WHO-TEQ g−1 fat and between 0.30 and 0.46 pg WHO-TEQ g−1 fat when results were calculated with the lower and medium bound values, respectively. Indicator PCB contamination levels were below 1 ng g−1 fat in all cases. Thus, the estimated daily intake of PCDD/Fs and indicator PCBs for infants has been assessed taking into account the above-mentioned contamination levels as well as different scenarios of body weight and food consumption data for babies aged 0–12 months. The results vary in the different scenarios considered but, on the whole, the daily estimated dioxin and indicator PCBs intake of the average infant population due to the consumption of infant formulae does not exceed the tolerable daily intake (TDI) of 2 pg WHO-TEQ kg−1 bw day−1 recommended by the Scientific Committee on Food (available at http://ec.europa.eu/food/fs/sc/scf/out90_en.pdf) nor the threshold value of 10 ng kg−1 bw day−1 proposed by the Dutch National Institute of Health and Environment (RIVM) (Baars et al. 2001. Report no. 711701025, National Institute of Public Health and the Environment (RIVM), Bilthoven, The Netherlands).

Removal of polychlorinated dioxins by semi-aerobic fed-batch composting with biostimulation of “Dehalococcoides”

A semi-aerobic, mesophilic, fed-batch composting (FBC) reactor loaded with household garbage was used to remove polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). The reactor was packed with woodchips as the solid matrix and PCDD/F-contaminated soil or flyash and then operated at a waste-loading rate of 0.5 kg (wet wt) day(-1). All congeners of PCDD/Fs (initial concentration, 200-830 pmol g(-1) [dry wt]) were totally reduced during the over period of operation, with a half reduction time of 4 months. Direct cell counting and respiratory quinone profiling showed that the reactors at the fully acclimated stage harbored a high population density of bacteria (10(11) g(-1) [dry wt]) with members of the Actinobacteria predominating. Real-time quantitative PCR showed that the population of "Dehalococcoides" and its phylogenetic relatives of Chloroflexi as the possible dechlorinators varied between at the order of 10(7) to 10(8) g(-1) (dry wt). A "Dehalococcoides"-containing dechlorinating culture from the soil-treating reactor was successfully enriched with a model PCDD/F compound, fthalide. 16S rRNA gene-targeted PCR-denaturated gradient gel electrophoresis and clone library analyses showed that this culture comprised at least three major phylogenetic groups of bacteria, Acidaminobacter, "Dehalococcoides," and Rhizobium. These results suggest that the semi-aerobic FBC process is applicable for the bioremediation of PCDD/Fs and possibly other haloorganic compounds with the biostimulation of "Dehalococcoides" and its relatives as the potent dechlorinators.

Characteritization of, and health risks from, polychlorinated dibenzo- p-dioxins/dibenzofurans from incense burned in a temple

Polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) may cause adverse health effects. However, PCDD/F emissions from burning incense in temples have rarely been addressed. This study investigates PCDD/F emissions from burning incense in a temple. The mean total PCDD/F concentrations were 72.4–82.2 pg Nm − 3 at two indoor sites; their corresponding mean total PCDD/Fs I-TEQ concentrations (0.24–0.27 pg I-TEQ Nm − 3 ) were ~ 11 times that at a background location. In air samples collected from burning incense, OCDFs accounted for approximately 90% of total PCDD/Fs at the two indoor sites and an outdoor site near the temple, while the major PCDD/Fs in incense ash were PCDDs. The total PCDD/F content and toxic equivalent value of incense ash were 617 pg g − 1 and 1.55 pg I-TEQ g − 1 , respectively. At the three sites inside/outside the temple, the air and ash samples contained the same four primary PCDD/Fs–OCDD, 1,2,3,4,6,7,8-HpCDD, OCDF and 1,2,3,4,6,7,8-HpCDF. The Cl − emission factor, which is related to the PCDD/F formation, from burning incense was 0.454 mg g − 1 . The resultant lifetime average daily dose and cancer risk for temple workers were 0.00964 pg I-TEQ day − 1 kg − 1 and 9.64 × 10 − 6 , respectively, approximately 2 times that for residents near the temple (0.00489 pg I-TEQ day − 1 kg − 1 and 4.89 × 10 − 6 , respectively). We suggest that the chlorine content in incense must be regulated, and the high risk of PCDD/F exposure from burning incense for temple workers and visitors should be of concern.