H. Thoma

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.

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.

Pcdd/F-concentrations in chimney soot from house heating systems

Abstract 50 different chimney soot samples from house heating in the area of Bayreuth, Germany, were analyzed for PCDD/F. The furnaces operated with wood, coal, wood/coal or oil. PCDD/F were detected in all samples and their isomer patterns were similar to those from municipal waste incinerators. Expressed as toxicity equivalents (Federal health office FRG) the following average concentrations were detected: oil (central heating) 147 ppt, oil (oven) 907 ppt, wood/coal (oven) 909 ppt, wood (central heating) 14896 ppt, wood (oven) 7489 ppt and coal (oven) 5120 ppt.

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.

Pyrolysis and GC/MS-analysis of brominated flame retardants in on-line operation

Abstract Flame retardants such as brominated diphenyl ethers (Bromkal 70-5-DE, FR 300 BA), 2,4,6-tribromophenol, pentabromophenol and hexabromobiphenyl were pyrolyzed at 600°C, 700°C, 800°C and 900°C in absence of oxygen in a SGE pyrojector, and the residues were analyzed by means of GC/MS in on-line operation. The pyrolysis of Bromkal 70-5-DE hereby yielded bromobenzenes (PBBz), bromophenols (PBP) and brominated dibenzofurans (PBDF). PBBz, bromonaphthalenes (PBN) and PBDF could be detected in the FR 300 BA pyrolysate, whereas brominated benzenes and dibenzodioxins formed during the pyrolysis of 2,4,6-tribromophenol. Unlike the pyrolysis of 2,4,6-tribromophenol, pentabromophenol pyrolysis produced mainly bromobenzenes along with traces of bromonaphthalenes, bromodioxins and bromodiphenyl ethers. The pyrogram of hexabromobiphenyl showed bromobenzenes and brominated biphenyls as key pyrolysate components.

Uptake and accumulation of PCDD/F in terrestrial plants: basic considerations

Abstract Uptake mechanisms of lipophilic chlorinated hydrocarbons into plants are discussed. The discussion focusses on the direct adsorption of atmospheric lipophilic gases onto plant surfaces. Some correlations are presented to estimate the accumulation of organic vapors on plant leaves.

Accumulation of organic air constituents by plant surfaces: Part IV: Plant surfaces: A sampling system for atmospheric polychlorodibenzo-p-dioxin (PCDD) and polychlorodibenzo-p-furan (PCDF)

Abstract The accumulation of airborne polychlorodibenzo-p-dioxin (PCDD)/polychlorodibenzo-p-furan (PCDF) in needles of spruce trees ( Picea abies ) was investigated to demonstrate the suitability of plant surfaces as natural monitors of emission levels in the environment. A simplified extraction procedure for the analysis of PCDD/PCDF and other highly lipophilic substances from plants is proposed.

Comparison of the polychlorinated dibenzo-p-dioxin and dibenzofuran in human tissue and human liver

Abstract Adipose tissue and liver samples of 28 people from the Munich area were analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F). The subjects were of different age, weight, size and sex. The clean up was a combination of methods described by Hummel and Nestrick and Lamparski. The identification and quantification of the purified extracts was achieved by HRGC/HRMS (resolution 5000) and addition of internal standards before the clean up. Only 2,3,7,8-substituted compounds were detected in all samples. The average concentrations in adipose tissue were: T 4 CDD: 8.0 ppt, P 5 CDD: 16.4 ppt, H 6 CDD: 94.7 ppt, H 7 CDD: 106.6 ppt, OCDD: 373.2 ppt, T 4 CDF: 2.5 ppt, P 5 CDF: 35.2 ppt, H 6 CDF: 41.5 ppt, H 7 CDF: 14.2 ppt, OCDF: 4.0 ppt and in liver (fat basis): T 4 CDD: 16.4 ppt, P 5 CDD: 20.1 ppt, H 6 CDD: 166.8 ppt, H 7 CDD: 1002.4 ppt, OCDD: 4416.2 ppt, T 4 CDF: 5.5 ppt, P 5 CDF: 173.7 ppt, H 6 CDF: 389.5 ppt, H 7 CDF: 218.9 ppt and OCDF: 29.7 ppt. Furthermore, adipose tissue samples from infants between the ages of 2 and 16 months were analyzed for PCDD/F. The average concentrations were: T 4 CDD: 3.0 ppt, P 5 CDD: 5.4 ppt, H 6 CDD: 25.5 ppt, H 7 CDD: 27.1 ppt, OCDD: 104.9 ppt, T 4 CDF: 2.1 ppt, P 5 CDF: 16.1 ppt, H 6 CDF: 10.4 ppt, H 7 CDF: 4.2 ppt and OCDF: 4.8 ppt.