CDDs) And Dibenzofurans Research Articles

Subchronic toxicity of Baltic herring oil and its fractions in the rat II: Clinical observations and toxicological parameters.

This study aimed to increase the knowledge about the toxicity of fish-derived organohalogen pollutants in mammals. The strategy chosen was to separate organohalogen pollutants derived from Baltic herring (Clupea harengus) fillet, in order to obtain fractions with differing proportions of identified and unidentified halogenated pollutants, and to perform a subchronic toxicity study in rats, essentially according to the OECD guidelines, at three dose levels. Nordic Sea lodda (Mallotus villosus) oil, with low levels of persistent organohalogen pollutants, was used as an additional control diet. The toxicological examination showed that exposure to Baltic herring oil and its fractions at dose levels corresponding to a human intake in the range of 1.6 to 34.4 kg Baltic herring per week resulted in minimal effects. The spectrum of effects was similar to that, which is observed after low-level exposure to pollutants such as chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/F) and chlorinated biphenyls, despite the fact that these contaminants contribute to a minor part of the extractable organically bound chlorine (EOCI). The study confirmed previous findings that induction of hepatic ethoxyresorufin deethylase (EROD) activity takes place at daily intake levels 0.15 ng fish-derived CDD/F-TEQs/kg body weight. The study also demonstrated that hepatic vitamin A reduction takes place at somewhat higher daily exposure levels, i.e. 0.16-0.30 ng fish-derived CDD/F-TEQs/kg body weight. Halogenated fatty acids, the major component of EOCI, could not be linked to any of the measured effects. From a risk management point of view, the study provides important new information of effect levels for Ah-receptor mediated responses following low level exposure to organohalogen compounds from a matrix relevant for human exposure.

Dioxin and furan formation on CuCl 2 from chlorinated phenols with one Ortho chlorine

The formation of chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) on CuCl2 particlesfrom four phenols with one ortho chlorine was studied in a flow reactor over the temperature range 300 to 450°C and contrasted with gas-phase results between 500 and 700°C. Heated nitrogen gas streams containing 7/8% oxygen, 1.7% benzene vapor, and equal amounts of 2-chlorophenol 2,3-dichlorophenol, 2,3,5-trichlorophenol, and 2,3,4,5-tetrachlorophenol vapor (450 ppmv, each) were passed through a particle bed containing 0.5% (mass) CuCl2: the nominal gas particle contact time was 0.3 s. CDD/F product yields of greater than 1% phenol conversion were observed between 350 and 425°C. Unlike gas-phase CDD/F formation, formation on CuCl2 favored CDDs over CDFs, and CDDs were formed predominantly with loss of one chlorine atom. While total CDD/F yields varied significantly with temperature, CDD/F isomer distributions did not. Thus, isomer patterns may provide a fingerprint for CDD/F formation from phenol precursors. Based on results of experiments with single phenol precursors, phenol precursors were assigned to all CDD/F products 2,3,4-Trichlorophenol was found to have the greatest propensity to form CDDs, whereas 2,3-dichlorophenol and 2,3,4,5-tetrachlorophenol were found to have the greatest propensity to form CDFs. Similar to gas-phase CDD/F formation, these results on CuCl2 suggest that chlorine substitution at phenol meta sites favors CDF formation, whereas chlorine substitution at ortho and para sites favors CDD formation.

Natural Formation of Chlorinated Phenols, Dibenzo-p-dioxins, and Dibenzofurans in Soil of a Douglas Fir Forest

The natural formation of 4-MCP, 24/25- and 26-DCP, and 245-TrCP was detected in four selected areas of a rural Douglas fir forest where the humic layer was spiked in situ with a solution of Na37Cl and covered by an enclosure, after 1 year of incubation. Chlorinated phenols (CP) can be formed naturally from organic matter and inorganic chloride by either de novo synthesis or chloroperoxidase (CPO)-catalyzed chlorination. The natural CP congeners were found to be present in high concentrations in soil compared to the other congeners, except for 245-TrCP which was present in a relatively low concentration. This study did not reveal which source, natural or anthropogenic, caused the observed concentrations. Some 20 chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/F) were found to be formed naturally in soil of the Douglas fir forest; the formation of three 2,3,7,8-substituted congeners, 2378-TeCDD, 12378-PeCDD, and 123789-HxCDD, deserves special attention. A formation mechanism has been proposed which starts from naturally formed CP congeners and which probably involves peroxidase mediation. Chlorination of CDD/F congeners by the CPO-mediated reaction cannot be ruled out, but seems to be less likely due to the absence of several predicted congeners.

Preliminary report: Dioxins and furans in prescribed burns

The Ontario Ministry of Environment (MOE) recently participated in a joint Canadian/U.S. program to monitor the behavior and environmental impact of prescribed fires. Air, soil and ash samples were collected at the burn sites and analyzed for chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF). Preliminary results indicated that larger air sample volumes were required.

Chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) in effluents and sludges from pulp and paper mills

Sludges and treated effluents from various Ontario pulp and paper plants were analyzed for chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs). Results show that 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-4CDD) is a product of bleached Kraft mills. The only CDD/CDF congeners found in more than one sludge sample were the tetrachlorinated CDDs (4CDD) and CDFs (4CDF) and octachlorinated CDD and CDF. Levels of 2,3,7,8-4CDD ranged from 170 to 370 ppt in the secondary treatment sludge from two bleached Kraft mills.

Determination of chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF) in environmental samples by tandem mass spectrometry

A round-robin study is reported which compares the technique of quadrupole MS/MS to that of HRMS and LRMS for the detection of CDD and CDF in typical environmental samples. Three different commercially available MS/MS instruments were included in the study. The data indicate that chromatographic pre-treatment of sample extracts can be reduced due to the additional selectivity of MS/MS. However, validation by comparative analysis is recommended.

Concentrations of chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF) in soil from the vicinity of a large refuse incinerator in Hamilton Ontario

Soil in the vicinity of a large municipal refuse incinerator was analyzed for CDDs/CDFs. Fourteen locations which included three control sites were examined. The results showed that CDDs/CDFs emitted from the incinerator since 1973 have not accumulated in surface soil in the vicinity of the plant.

Novel extraction device for the determination of chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) in matrices containing water

The efficient extraction of CDDs/CDFs from particulate matrices containing measurable amounts of water is complicated by the need to remove the water from the particles before beginning the extraction process. Traditionally, this has been done by pre-extracting the sample with a water miscible solvent such as isopropanol or by air drying for an extended period of time over various desiccants such as sulfuric acid or phosphorus pentoxide. These techniques can suffer from three possible problems: potential loss of analytes, accidental sample contamination, or an unacceptably long sample drying time. In response to these drawbacks, we have developed an extraction device that combines the simultaneous removal and measurement of water from a particulate sample with an exhaustive Soxhlet extraction of the dried particulates.

Concentrations of chlorinated dibenzo-p-dioxins and dibenzofurans in effluents and centrifuged particulates from Ontario pulp and paper mills

Chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs) were determined in effluents and centrifuged particulates from nine pulp and paper mills situated in Ontario, Canada. The centrifuged particulates from all mills contained some CDD/CDF congeners, although they were not always detected in the corresponding effluents. The greatest concentrations of CDDs/CDFs were found in the effluents and particulates from the bleached kraft mills, where the tetrachlorinated CDDs/CDFs were the predominant congeners.

Gas chromatographic/mass spectrometric determination of chlorinated dibenzo-p-dioxins and dibenzofurans in incinerator stack emissions and fly-ash: A 13-test study

A 13-test study was performed to determine whether the overfire air and nominal steam load of a waste-to-energy municipal incinerator could be adjusted to minimize formation of the chlorinated dibenzo-p-dioxins (CDDs) and dibenzofurans (CDFs). Stack emissions and precipitator fly-ash were analyzed for chlorobenzenes, chlorophenols, and polychlorinated biphenyls in addition to the CDDs/CDFs. The results showed that efficient collection of stack-emitted CDDs/CDFs was obtained, and that a single overnight soxhlet extraction with toluene was sufficient for complete recovery of all extractable CDDs/CDFs in fly-ash. No strong correlations were observed between the incinerator variables studied and the CDD/CDF emissions. Likewise, no strong correlations between the concentrations of CDDs/CDFs in stack emissions and concentrations of precursors were obtained, although some trends were observed. Results suggest that the CDD:CDF ratio and relative CDD/CDF congener distributions may be affected by incinerator conditions. Although a specific set of incinerator conditions to minimize CDD/CDF emissions were not developed, it was found that with efficient incinerator operation these emissions can be held below the Ontario provisional guideline.

Reporting chlorinated dibenzo-p-dioxin and dibenzofuran data in scientific publications

A literature review of recent work involving the determination of chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF) in fish and incinerator samples has shown many irregularities and omissions in the reported data. Although some of these result from non-standardized nomenclature and reporting practices and do not affect the overall conclusions reached, in some cases omissions in reporting experimental procedures raise important concerns regarding the validity of data and make comparison of data from different investigations difficult. It is not always necessary or even desirable to report every experimental detail of work performed, however, the ultra-trace determination of CDDs and CDFs in complex environmental samples is still at a stage where omission of key experimental details can affect the interpretation of results.

Characteristics of an extraction and purification procedure for chlorinated dibenzo- p-dioxins and dibenzofurans in soil and liver

Liver is extracted with chlorofor—methanol to give essentially quantitative transfer of endogenous chlorinated dibenzo- p-dioxins (CDDs) and dibenzofurans (CDFs) into the organic phase. A new procedure involving LH-20 Sephadex is used to remove most of the lipids from the extract. Soil es extracted by a simple, rapid and economical procedure giving very high recoveries of CDDs and CDFs from sandy soil, various types of clay, and humus-rich loam. Subsequent cleanup on basic and acidic alumina complete the preparation for gas chromatography-mass spectrometric analysis. The use of propylene glycol as a “keeper” and of 2,3,7-trichlorodibenzo- p-dioxin as a carrier minimizes losses during evaporation of solvents and on glass surfaces. Interactions of 2,3,7,8-CDD with organic material in loam slightly reduce recovery but thre is no indication of high affinity binding sites, the losses being apparently associated with simple distribution coefficients. Special precautins needed to avoid losses of CDFs on alumina chromatography are described, and the effect of “aging” spiked soil is discussed.