By-side chlorodibenzo-P-dioxins and chlorodibenzofurans in technical chlorobiphenyl formulations of aroclor 1268, chlorofen, and clophen T 64

Characterization of PCDD/Fs and dl-PCBs emission from combustion of PCB-containing oil in a fluidized-bed incinerator

Emissions of PCDD/Fs and dl-PCBs from the combustion of PCB-containing oil in a hazardous waste incinerator are characterized. Flue gas samples are simultaneously taken at three points, including the outlet of ultrasonic wet scrubber, the outlet of heat exchanger and stack. In addition, solid matter samples including incinerator bottom ash, wet scrubber sludge, heat exchanger ash and baghouse ash are also collected. The results indicate that TEQ concentration (PCDD/Fs + dl-PCBs) measured in stack from the combustion of PCB-containing oil is 0.51 ng WHO-TEQ/Nm³. For the solid matter, PCDD/F and dl-PCB concentrations of baghouse ash and wet scrubber sludge are significantly higher than those measured in bottom and heat exchanger ashes. The total removal efficiencies of PCDD/Fs + dl-PCBs achieved with bag filtration (BF) + activated carbon injection (ACI) reaches 65.0%. The emission factors of PCDD/Fs and dl-PCBs from incinerating PCB-containing oil are 1.05 and 0.08 ng WHO-TEQ/L, respectively. The overall PCDD/Fs and dl-PCBs destruction efficiencies achieved with fluidized-bed incinerator reach 99.87% and 99.9998%, respectively, which demonstrates that incineration is an effective engineering practice for treating PCB-containing oil. Moreover, this is the first study suggesting the ratios of PCB-114/(PCB-126+ PCB-114) and PCB-157/(PCB-169+ PCB-157) as indicators to distinguish the emission source of dl-PCB from combustion process and technical mixture evaporation in diagnostic ratio analysis.

Enzyme induction and histopathology elucidate aryl hydrocarbon receptor-mediated versus non-aryl hydrocarbon receptor-mediated effects of Aroclor 1268 in American mink (Neovison vison)

Polychlorinated biphenyl (PCB) concentrations reported in preferred prey and blubber of bottlenose dolphins from the Turtle-Brunswick River estuary (Georgia, USA) suggest the potential for adverse effects. However, PCBs in Turtle-Brunswick River estuary dolphins are primarily derived from Aroclor 1268, and predicting toxic effects of Aroclor 1268 is uncertain because of the mixture's unique composition and associated physiochemical characteristics. These differences suggest that toxicity benchmarks for other PCB mixtures may not be relevant to dolphins exposed to Aroclor 1268. American mink (Neovison vison) were used as a surrogate model for cetaceans to characterize mechanisms of action associated with Aroclor 1268 exposure. Mink share similarities in phylogeny and life history with cetaceans and are characteristically sensitive to PCBs, making them an attractive surrogate species for marine mammals in ecotoxicity studies. Adult female mink and a subsequent F1 generation were exposed to Aroclor 1268 through diet, and effects on enzyme induction, histopathology, thyroid hormone regulation, hematology, organ weights, and body condition index were compared to a negative control and a 3,3',4,4',5-pentachlorobiphenyl (PCB 126)-positive control. Aroclor 1268 dietary exposure concentrations ranged from 1.8 µg/g wet weight to 29 µg/g wet weight. Anemia, hypothyroidism, and hepatomegaly were observed in mink exposed to Aroclor 1268 beyond various dietary thresholds. Cytochrome P450 induction and squamous epithelial proliferation jaw lesions were low in Aroclor 1268 treatments relative to the positive control. Differences in enzyme induction and the development of squamous epithelial proliferation jaw lesions between Aroclor 1268 treatments and the positive control, coupled with effects observed in Aroclor 1268 treatments not observed in the positive control, indicate that mechanisms additional to the aryl hydrocarbon receptor-mediated pathway are associated with Aroclor 1268 exposure.

Relative potencies of aroclor mixtures derived from avian in vitro bioassays: comparisons with calculated toxic equivalents

The World Health Organization toxic equivalency factors (WHO-TEFs) for birds were developed to simplify risk assessments of environmental mixtures of dioxin-like compounds (DLCs). Under this framework, toxic equivalents (TEQs) are used to represent the toxic potency of DLC mixtures as an equivalent concentration of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Recently, a luciferase reporter gene (LRG) assay, measuring aryl hydrocarbon receptor 1 (AHR1)-mediated gene expression, accurately predicted the relative potency of individual polychlorinated biphenyl (PCB) congeners in different avian species. The study presented here used the LRG assay to predict the relative potency of Aroclors 1016, 1221, 1242, 1248, 1254, and 1260 on induction of LRG activity in cells transfected with chicken, ring-necked pheasant, or Japanese quail AHR1 constructs. LRG assay results were compared to (1) results of ethoxyresorufin-O-deethylase (EROD) assays conducted in chicken hepatocytes and (2) calculated TEQs from the literature. The relative potencies of Aroclors were similar between the LRG and EROD assays, and bioassay-derived TEQs for the chicken closely resembled calculated TEQs. However, LRG assay-derived TEQs for the Japanese quail construct were 1-2 orders of magnitude higher than calculated TEQs for Aroclors 1254 and 1016. These results suggest that the WHO-TEFs are not representative of relative PCB potency for all avian species.

Dioxin-like compound compositional profiles of furnace bottom ashes from household combustion in Poland and their possible associations with contamination status of agricultural soil and pine needles

A compositional profile of PCDDs, PCDFs, non- and mono-ortho PCBs, and PCNs of several type furnace bottom ashes obtained after the heating muffle stove for domestic use combustion of hard coal, coke, wood, and solid domestic waste mixture have been examined as possible contributors to environmental diffusion with these compounds in Poland. The uppermost concentration of dioxin-like compounds with 2.0 ng TEQ kg(-1) dry weight found for wood ash was dominated by PCDDs and PCDFs, while for other types of ashes were in the range from 0.052 ng TEQ kg(-1) to 0.67 ng TEQ kg(-1) dry weight. The multivariate statistical analysis displayed some compositional similarity of PCDDs, PCDFs and PCNs between the ashes and environmental pine needle or agricultural soil matrices collected in Poland.

Polychlorinated dibenzo-p-dioxins (PCDDs) and -furans (PCDFs) in pine needles of Poland

There is scarcity of data on sources, environmental diffusion and concentrations of PCDD/Fs and dioxin-like compounds in the Eastern and Central Europe. A study has been conducted using pine needles as passive matrix on diffusion of airborne 17 highly toxic PCDD/Fs in Poland. The target compounds were quantified using isotope dilution and HRGC/HRMS. One-year-old pine needles collected from 25 spatially distant sites in October 2002 revealed a relatively very low aerial emission and degree of pollution with PCDD/Fs. The most toxic 2,3,7,8-TCDD was absent (< 0.44 pg/g) in fresh pine needles sampled and absent at all sites were also 1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9-HxCDD and 1,2,3,7,8,9-HxCDF (< 0.27 pg/g). OCDD at concentration range from 1.4 to 34 pg/g and OCDF at range from 1.5 to 41 pg/g were the only among 17 compounds found at each site, and next in prevalence was 1,2,3,4,7,8,9-HpCDF (total range from < 0.41 to 8.1 pg/g), which was found at 24 off 25 sites. The I-TEQ transformed concentrations of PCDD/Fs of pine needles of Poland ranged from < 0.01 to 1.28 pg/g ww or from 0.01 to 3.18 pg/g dw. The CDD/F homologue groups and congeners profiles of pine needles with highly dominant HpCDD/F and OCDD/F found in this survey suggest on lack of significant other than coal/lignite/wood combustiont sources of PCDD/Fs diffusion to ambient air in Poland.