benzofurans and octachlorodibenzo-4-dioxin

Winam Gulf of Lake Victoria is considered to be contaminated with toxic chemicals emanating from anthropogenic activities, especially near large industrial towns such as Kisumu. This has recently caused concerns about its water quality and impact on aquatic organisms and human beings. This study was justified by the need to generate baseline concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in surface sediment from selected sites in the lake and determine the influence of activities on their concentrations and potential risks to fish-eating birds living near the lake. Surface sediments (<30cm) from three different fish landing beaches, located 200m from the shore of Winam Gulf of Lake Victoria near Kisumu city, Homa Bay and Mbita (control) towns, were analysed. The total mean concentrations (in pgg(-1)drywt) were found to range from 17.4-812 (Σdl-PCBs), 36.6-813 (ΣPCDDs) and 1.45-46.4 (ΣPCDFs). The calculated Toxic Equivalents (TEQWHO(2005)) ranged from 0.001-0.43 (Σdl-PCBs) and 0.09-31 (ΣPCDD/Fs). The fish landing beaches at Kisumu city were found to be contaminated with respect to dl-PCBs and dioxins, followed by Homa Bay and Mbita. The relatively high levels of octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) influenced the TEQ and the ΣPCDFs/ΣPCDDs ratios indicated chemical processes as partial sources of the dioxins. The levels of contaminants obtained in this study showed potential exposure to aquatic organisms and fish eating birds through food chain transfer.

Topics: Benzofurans; Dibenzofurans, Polychlorinated; Kenya; Lakes; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins; Water Pollutants, Chemical

Topics: Benzofurans; Environmental Pollutants; Halogenation; Photolysis; Polychlorinated Dibenzodioxins; Solvents

Comprehensive congener fingerprints of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), including non-2,3,7,8-substituted congeners, in 142 surface sediment samples from the Baltic Sea were characterized by Principal Component Analysis (PCA). The pattern analysis revealed source specific indicators of chlorophenol use, high temperature processes, chlorine bleach/chloralkali production and a source signature suggested to originate from pulp/paper or related production. Congener patterns in sediments from offshore and pristine coastal areas showed strong resemblance to patterns of atmospheric deposition and flue gases, indicating that these sources have high impact in areas that are not affected by point sources. Prominent contributors to the patterns of hotspot areas along the Swedish coast included chlorophenol indicators and a source characterized by hexa-CDDs while the contribution of the traditional chlorine bleach pattern was weaker. This study demonstrates the importance of comprehensive PCDD/F congener analysis for identifying links to candidate sources.

Topics: Benzofurans; Dibenzofurans, Polychlorinated; Environmental Monitoring; Geography; Geologic Sediments; Oceans and Seas; Polychlorinated Dibenzodioxins; Principal Component Analysis; Seawater; Water Pollutants, Chemical

Model dioxin compounds 4-chlorobiphenyl (4CB), octa-chlorodibenzo-p-dioxin (OCDD), and octachlorodibenzofuran (OCDF) were degraded by a mechanochemical (MC) process that involved milling with calcium oxide by use of a planetary ball mill. The degradation of 4CB produced mainly chloride ions and biphenyl, with the chlorine removal efficiency reaching about 100%. Biphenyl was transformed into terphenyls, quaterphenyls, cyclohexylbenzene, and bicyclohexyl through polymerization and hydrogenation reactions. Measurements of chloride ions after MC treatment of OCDD and OCDF showed about 100% dechlorination of both compounds; tetra- to heptachlorinated dibenzo-p-dioxins/furans (T4-H7CDD/Fs) were detected only at trace levels, and no other chlorinated organic compounds were observed. The residue after MC treatment was gray in color, indicating the possibility of carbonization, but the presence of amorphous graphite could not be confirmed.

Topics: Benzofurans; Biphenyl Compounds; Calcium Compounds; Chlorine; Environmental Pollutants; Gas Chromatography-Mass Spectrometry; Oxides; Polychlorinated Dibenzodioxins; Steel; Waste Management; X-Ray Diffraction

Previous studies with octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) in juvenile or adult fish exposed via water revealed no toxicity, despite significant bioaccumulation. With 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), the fish early-life stage study has been shown to be the most sensitive test system. Therefore, the effects of OCDD and OCDF on the early-life stages of zebra fish (Brachydanio rerio) were determined during a flow-through test based on a column generator method. No statistically significant effect of OCDD and OCDF on the survival and hatching time of the eggs was found. Furthermore, no effects on survival, weight, general appearance or behaviour of the larvae were observed at the end of the exposure period of 32 days. GC-MS analysis of test solution samples revealed geometric mean measured concentrations of 32 (OCDD) and 34 ng/l (OCDF), respectively. Concentrations in surviving larvae at the end of the study were 61 (OCDD) and 94 (OCDF) micrograms/kg, respectively. These concentrations in zebra fish larvae were several orders of magnitude higher than concentrations in fish collected from the wild. In a review of the available laboratory fish experiments, we found a lack of biomagnification of OCDD and OCDF. We do not expect to find adverse effects of these compounds on the aquatic environment.

Topics: Animals; Benzofurans; Female; Growth; Male; No-Observed-Adverse-Effect Level; Polychlorinated Dibenzodioxins; Tissue Distribution; Zebrafish

Organochlorines are persistent and highly lipophilic environmental contaminants which bioaccumulate in the food chain. Some of these chemicals, 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) and polychlorinated biphenyls (PCBs), have been suggested to be of significance in the aetiology of breast cancer. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an anti-oestrogen in animal studies and should be thus lower the risk of breast cancer. The other isomers of polychlorinated dibenzo-p-dioxins (PCDDs) or the chemically related polychlorinated dibenzofurans (PCDFs) have not been tested regarding carcinogenesis of the breast. The purpose of this study was to investigate whether PCDDs or PCDFs influence the risk for breast cancer. Consecutive patients who underwent surgery for a breast disease between 1993 and 1995 were recruited for the study. Cases were 22 patients with infiltrative breast cancer and controls were 19 patients operated for a benign breast disease during the same time period. Approximately 10 g of breast tissue free from tumour was taken from the specimen and frozen until analysis. Fat was extracted, cleaned and analysed with a high-resolution gas chromatograph coupled to a high-resolution mass spectrometer. Median concentrations of octachlorinated dibenzo-p-dioxin (OCDD) were 598 (170-14,880) and 396 (103-1,847) pg/g lipid in the cases and in the controls, respectively. In a multivariate logistic regression analysis controlling for other risk factors for breast cancer increased odds ratio (OR) was obtained for OCDD: 401-1000 pg/g lipid yielded OR 3.8, 95% confidence interval (CI) 0.4-39, > 1000 pg/g lipid gave OR 5.2, CI 0.4-72. When the lipid OCDD variable was examined as a continuous risk factor there was a 1.09 (9%), CI 0.95-1.25, increase in the adjusted OR for breast cancer per 100 unit (pg/g lipid) increase in OCDD. No differences were found between cases and controls for the other six tested PCDDs. Mean concentration of TCDD was in the cases 3.6 (1.0-7.9) and in the controls 3.3 (1.1-6.3) pg/g lipid. For PCDFs no significant differences were found between cases and controls. The results were not changed if oestrogen or progesterone receptor status, S-phase fraction and DNA ploidy were considered. Breast tissue concentration of OCDD was increased in cancer patients, whereas the concentrations of other PCDDs and PCDFs were equal in cases and controls.

Topics: Adult; Aged; Benzofurans; Breast Neoplasms; Case-Control Studies; Female; Humans; Logistic Models; Middle Aged; Odds Ratio; Polychlorinated Dibenzodioxins; Polymers; Risk Factors; Soil Pollutants