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Sökning: AMNE:(NATURAL SCIENCES Chemistry Environmental chemistry) > (1990-1999) > Dioxins :

LIBRIS Formathandbok  (Information om MARC21)
FältnamnIndikatorerMetadata
00006188naa a2200373 4500
001oai:DiVA.org:oru-47662
003SwePub
008160119s1990 | |||||||||||000 ||eng|
024a https://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-476622 URI
024a https://doi.org/10.1080/027722490093576282 DOI
040 a (SwePub)oru
041 a engb eng
042 9 SwePub
072 7a ref2 swepub-contenttype
072 7a art2 swepub-publicationtype
100a Fiedler, Heidelore,d 1953-u Chair of Ecological Chemistry and Geochemistry, University of Bayreuth, Bayreuth, Germany4 aut0 (Swepub:oru)hefr
2451 0a Dioxins :b Sources of environmental load and human exposure
264 1b Taylor & Francis,c 1990
338 a print2 rdacarrier
520 a Polychlorinated dibenzo‐p‐dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) represent a class of tricylic, almost planar, aromatic ethers with 1 to 8 chlorine atoms. Congeners with substituents in the positions 2, 3, 7, and 8 are of special concern due to their toxicity, stability, and persistence. These compounds have been identified in almost all environmental compartments and humans.Dioxins are a potent carcinogen for animals and—at the moment—considered a probable carcinogen for humans. Actual toxicological risk assessment for humans are based on 2,3,7,8‐Cl4DD carcinogenicity studies on rodents. Tumorigenic effects were found for 2 strains of rats and 2 strains of mice. All dioxins and furans elicit common toxic and biological responses, starting with a specific binding to a protein receptor, but existing epidemiologic data do not provide definitive data on human health effects.Toxicity equivalency factors (TEFs) have been developed by several agencies as a provisional method of risk assessment for complex mixtures of PCDD/PCDF.Dioxins have never been produced intentionally and have never served any useful purpose. They are formed in trace amounts as by‐products in industrial processes; for instance within the chemical industry, of the pulp and paper industry, metallurgical processes, processes for reactivation of granular carbon, dry cleaning, and the manufacture of flame‐retarded plastics.The main pathway for dioxins to enter the environment is via combustion processes. Incineration is of special importance since PCDD/PCDF are directly released to the atmosphere from either stationary sources, such as municipal, hazardous and hospital waste incinerators, the combustion of sewage sludge, and scrap metal recycling, or diffuse sources, e.g. automobile exhausts, private home heating with fossil fuels, forest fires, and cigarette smoking. Furthermore, fires with PCB and PVC have additionally contributed to the total dioxin load. The emission gases can undergo long‐range transport, so that dioxins have been found even in remote areas.Besides the two primary sources (industrial processes and combustion processes) the release of dioxins from contaminated areas and waste dumps via the leachate and the application of sewage sludge for fertilization represents a third source of PCDD/PCDF.After more than 10 years of dioxin research the most important sources of PCDD/PCDF have been identified and analytical methods have been developed for their quantification in trace levels and in complex matrices.Various efforts have been undertaken to reduce the emission of dioxins: for example, optimization of combustion processes for municipal waste incineration, use of unleaded gasoline, ban of chemicals, such as polychlorinated biphenyls (PCBs) and pentachlorophenol (PCP). More detail is provided in the pulp and paper section where changes have been initiated to significantly reduce the sources of PCDD/PCDF.However, relatively little is known about transport and transformation processes, so only rough estimates can be made. Photodegradation has been found to be the primary process for 2,3,7,8‐Cl4DD breakdown. A half‐life of 3–4 days has been estimated for photochemical degradation under oxidative conditions. Field studies on the fate of 2,3,7,8‐Cl4DD in soil gave a half‐life of 9.1 (Seveso) and 12 years (under special conditions: sand, erosion), respectively. Biodegradation seems to be negligible. Transfer factors soil‐plants for PCDD/PCDF have been determined—with a high degree of uncertainty—to be less than 0.1.Human exposure primarily occurs via ingestion whereas inhalation is a minor pathway. Dermal absorption can be neglected although skin contact to polluted surfaces may occur. Due to the lipophilicity of PCDD/PCDF and their potential for accumulation, foods such as meat and especially dairy products contribute most to the dioxin body burden of humans.Both national agencies and international organizations have recognized the significance of this problem and as a result have initiated regulations, recommendations and research programmes (1) to understand where and how PCDD/PCDF are formed, (2) to reduce their impact on the environment and to humans, and (3) to start remedial action on contaminated areas.
650 7a NATURVETENSKAPx Kemi0 (SwePub)1042 hsv//swe
650 7a NATURAL SCIENCESx Chemical Sciences0 (SwePub)1042 hsv//eng
650 7a NATURVETENSKAPx Geovetenskap och miljövetenskapx Miljövetenskap0 (SwePub)105022 hsv//swe
650 7a NATURAL SCIENCESx Earth and Related Environmental Sciencesx Environmental Sciences0 (SwePub)105022 hsv//eng
653 a Kemi
653 a Chemistry
653 a Enviromental Science
653 a Miljövetenskap
700a Hutzinger, O.u Chair of Ecological Chemistry and Geochemistry, University of Bayreuth, Bayreuth, Germany4 aut
700a Timms, C. W.u Procter & Gamble GmbH, Schwalbach am Taunus, Germany4 aut
710a Chair of Ecological Chemistry and Geochemistry, University of Bayreuth, Bayreuth, Germanyb Procter & Gamble GmbH, Schwalbach am Taunus, Germany4 org
773t Toxicological & Environmental Chemistryd : Taylor & Francisg 29:3, s. 157-234q 29:3<157-234x 0277-2248x 1029-0486
8564 8u https://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-47662
8564 8u https://doi.org/10.1080/02772249009357628

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