Otto Hutzinger

Relationship between bioconcentration in fish and steric factors of hydrophobic chemicals

Abstract Most polychlorinated naphthalones (PCN) accumulate rapidly according to their hydrophobicity. The uptake and ellmination rate constants are comparable to those of chlorinated benzenes and biphenyls. For most PCN-congeners the resulting bioaccumulation factors show an increase with increasing hydrophobicity. For higher K d,oct -values (>10 5 ) however, no further increase of K c is observed (K c. max. = 3.5.10 4 ). For the two hepta- and the octachloronaphthalenes no detectable concentrations are found in the fishes, although no restricted blo-availability could be expected. Based on these observations and on data obtained from the literature. a loss of membrane permeation is suggested for hydrophobic molecules with widths over 9.5 A. In addition a membrane permeation model, as part of the accumulation process of hydrophobic chemicals. Is proposed, which is based on diffusion and partition processes.

Dioxins : Sources of environmental load and human exposure

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 assessmen...

Polybrominated dibenzofurans (PBDF) and dibenzodioxins (PBDD) from the pyrolysis of neat brominated diphenylethers, biphenyls and plastic mixtures of these compounds

Abstract Representing typical flame retardants, bromkal 70 DE and 70-5-DE (brominated diphenylethers), Bromkal G1 (pentabromodiphenylether), FR 300 BA (decabromodiphenylether) and Fire Master BP-6 (hexabromobiphenyl) were heated in a quartz tube at 700°C, 800°C and 900°C, and their residues were tested for PBDD and PBDF. Mono- to penta-BDF as well as mono- to tetra-BDD were found in yields of up to 90% in Bromkal 70 DE, 70-5-DE and Bromkal G1. The optimal temperatures of formation hereby were between 700°C and 800°C. The residues of decabromodiphenyloxide contained tetra- to octa-BDF along with hepta- and octa-BDD, whereby the optimal formation temperatures were 800°C and 900°C. Furthermore, the pyrolysis of hexabromobiphenyl yielded di- to hepta-BDF. In a second series of tests, flame retardants were mixed with polystyrene and polyethylene, melted at 200°C and then pyrolyzed at 700°C, 800°C and 900°C. The residues of the mixtures polystyrene/Bromkal 70-5-DE and polyethylene/Bromkal 70-5-DE contained mono- to penta-BDF congeners. Mono-, di-, tri- and tetra-BDF could be detected in the pyrolysates of polystyrene- and polyethylene-decabromodiphenylether. The analysis of the polystyrene- and polyethylene-hexabromobiphenyl pyrolysates yielded mono- to tetra-BDF.

Polybrominated dibenzodioxins and -furans from the pyrolysis of some flame retardants

Abstract Purified 2,4,6-Tribromophenol, Pentabromophenol, Tetrabromobisphenol A and Tetrabromophthalic anhydride were pyrolyzed at 700°C, 800°C and 900°C. DBrDD, T3BrDD, T4BrDD (up to 89.6%), PBrDD, DBrDF, T3BrDF, and PBrDF were formed from 2,4,6-tribromophenol. From pentabromophenol PBrDD, H6BrDD, H7BrDD, OBrDD, PBrDF, H6BrDF, H7BrDF and OBrDF were formed. The burning of tetrabromobisphenol A gave MBrDD, DBrDD, T3BrDD, T4BrDD, MBrDF, DBrDF, T3BrDF and T4BrDF. In the residues of thermal reactions from tetrabromophthalic anhydride no PBrDD/PBrDF could be found. In all these studies the maximum of PBrDD/PBrDF-formation was at 800°C. The absence of PBrDD(PBrDF from the pyrolysate of tetrabromophthalic anhydride may guide the development of new brominated flame retardants, since certain structural features may suppress the formation of PBrDD/PBrDF.

PCDD/F in an agricultural food chain. Part 1: PCDD/F mass balance of a lactating cow.

Abstract A mass balance was conducted of the PCDD/F fluxes into and out of a lactating cow in an unmodified environment. Feed was found to be responsible for virtually all of the cows PCDD/F exposure. Approximately 20% of the 2,3,7,8-Cl4DD toxic equivalents taken up by the cow was excreted in the milk. The measured transfer rates for a cow in a natural state generally agreed well with the results from feeding experiments in the literature. The digestive tract resorption of PCDD/F decreased with increasing degree of chlorination. Both the feces and the milk were important routes for the excretion of persistent PCDD/F isomers.

Occurrence and distribution of atmospheric organic micropollutants in conifer needles

Abstract The distribution of some chlorinated hydrocarbons(p,p′-DDT, p,p′-DDE,α-HCH,γ-HCH,HCB) in spruce (Picea abies) needles was investigated. A comparision of concentrations in the wax with that of the remaining needle and time-resolved washing of the needle-surface shows the distribution behaviour of these substances.

Thermal formation of polybrominated dibenzodioxins (PBDD) and dibenzofurans (PBDF) from bromine containing flame retardants

Abstract The incineration of bromine containing flame retardants has been studied at different types of ovens (DIN-, BIS- and VCI-apparatus). Polybrominated dibenzofurans have been detected in the combustion products. Brominated diphenyl ethers yield concentrations up to 16% by incineration in a polymer matrix. The temperature profile depends largely on the type of polymer.

Surface-catalyzed formation of chlorinated dibenzodioxins and dibenzofurans during incineration

Abstract Surface-catalyzed reactions occuring on fly ash are the major contributors to the formation of chlorinated dioxins and furans produced during the incineration process. We investigated the relative importance of dioxin and furan formation via de novo synthesis from particulate carbon and via reactions of other precursors on fly ash. The levels of dioxins produced from pentachlorophenol were very much higher than those produced from carbon. Yields from both processes were strongly influenced by flow rate and heating time, however the two processes were affected differently. Carbon also acted to catalyze the formation of dioxins from pentachlorophenol.

PBDF and PBDD from the combustion of bromine containing flame retarded polymers: A survey

Abstract The formation of polybrominated dibenzofurans (PBDF) and dibenzodioxins (PBDD) during the pyrolysis of different polymers containing brominated organic flame retardants was investigated. The pyrolyses were conducted at two different temperatures (600°C and 800°C) using three different oven configurations. Both the pyrolysis gases and the solid residues were analysed for PBDF and PBDD. PBDF were found in almost all samples, but both the concentration and the degree of bromination varied greatly. The largest yields of PBDF in the percent range were measured in the pyrolysis products of polymers containing brominated diphenyl ethers. The other flame retardants generally yielded only a few ppm of PBDF. PBDD are formed only in a few samples and related to the PBDF in very low concentrations.

From source to exposure: Some open questions

PCDD/PCDF are trace contaminants in industrial and thermal processes, whose formation often cannot be avoided. Although the most important sources seem to be recognized within the last years new sources have been discovered. Very often only limited data are available. For the understanding of human exposure it is necessary to understand the pathways from the source to target organs or organisms. Environmental concentrations of dioxins have to be analyzed under ectoxicological aspects. Transfer and transformation mechanisms to be considered are: evaporation, deposition, erosion, photochemical degradation