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At least 19 recordsLinked to original sources

PubMed2000

Polymer additive analysis by pyrolysis-gas chromatography. II. Flame retardants.

Flame retardants are widely used in thermoplastic polymers for household and transportation applications. Flame retardants as well as most of the other additives in the polymer can be qualitatively analyzed by pyrolysis-gas chromatography (Py-GC) simultaneously with the polymer composition. The key to successful analysis of flame retardants not only requires a thorough knowledge of the various types of flame retardants but also necessitates an understanding of the parent polymer and its targeted applications. In this study, several flame retardants in different polymer matrices have been studied to demonstrate the utility of Py-GC for the analysis of flame retardants. The advantages of Py-GC for flame retardants analysis have also been discussed.

Chromatography, Gas↗

PubMed2001

In vitro dermal absorption of flame retardant chemicals.

Flame retardant chemicals may be used in furniture fabric in the future to reduce the flammability of the fabric. As a part of the process to evaluate the potential for exposure to these chemicals, this study examined the in vitro dermal absorption of two flame retardant chemicals. The chemicals were [14C]decabromodiphenyl oxide (DBDPO) and [14C]tris-(1,3-dichloro-2-propyl)phosphate (TDCP). Skin from the adult hairless female mouse (SKH1) was removed and mounted in flow-through diffusion cells. The chemicals, at three dose levels (DBDPO: 6, 30 and 60 nmol; TDCP: 20, 100 and 200 pmol), were applied in a volatile vehicle (tetrahydrofuran for DBDPO; acetone for TDCP) to the skin. Fractions of receptor fluid, pumped below the skin, were collected over a 24-h period. The skin was washed with solvent (tetrahydrofuran for DBDPO; ethanol for TDCP) to remove unabsorbed chemical 24 h after application. The receptor fluid, skin wash and skin were analyzed for chemical-derived radioactivity. The skin from the high-dose group of both chemicals, and the receptor fluid from TDCP high-dose samples, were analyzed for parent compound and metabolites by HPLC. The 24-h cumulative percent of the dose of DBDPO in the receptor fluid was very low (0.07-0.34%). The applied dose of DBDPO detected in the skin ranged from 2 to 20%. The lowest dose of DBDPO had the highest percentage of the dose (20%) in the skin. The major portion of the applied dose was removed by washing the skin 24 h after application of DBDPO, and ranged from 77 to 92%. HPLC analysis of homogenate extract prepared from the high-dose of DBDPO-treated skin showed the presence of DBDPO and a minor unknown peak. TDCP was readily detected in the receptor fluid; 39-57% of the applied dose of TDCP was in the receptor fluid by 24 h. The solvent wash removed 11-25% of the dose from the skin and 28-35% remained in it. HPLC analysis of the skin homogenate extract and receptor fluid extract from the TDCP high-dose treated samples showed the presence of parent compound and a minor unknown peak. TDCP more readily penetrated hairless mouse skin and diffused into the receptor fluid than DBDPO. TDCP has a lower molecular weight and log octanol:water partition coefficient than DBDPO. The differences in the physico-chemical properties of these two chemicals most likely explains their dissimilar absorption through hairless mouse skin.

Administration, Cutaneous↗

PubMed2002

PBCDD and PBCDF from incineration of waste-containing brominated flame retardants.

Brominated organic flame retardants comprise a large, heterogeneous group of compounds that are useful but also potentially damaging to the environment. In this investigation, three common brominated flame retardants were co-combusted with an artificial municipal solid waste in a pilot-scale fluidized bed incinerator. Combustion conditions ensured degradation of the flame retardants, but stable brominated organic compounds such as polybrominated dibenzo-p-dioxins and polybrominated dibenzofurans were formed in the cooling flue gases. The incineration of fuels that contain both chlorine and bromine leads to the formation of a complex mixture of polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans. More bromination than chlorination was observed in these experiments, and the chlorination levels increased when bromine was added to the fuel. The most favored reactions led to the formation of dibromodichlorodibenzo-p-dioxin and dibromodichlorodibenzofuran. Theoretical calculations show that there is more Br2 than Cl2 in the flue gas when the two halogens are present at equimolar levels, because chlorine is mainly found in the form of HCl. This may explain the higher bromination level. BrCl is also present, which drives the chlorination observed when bromine is added.

Benzofurans↗

PubMed2004

Analysis of Ah receptor pathway activation by brominated flame retardants.

Brominated flame-retardants (BFRs) are used as additives in plastics to decrease the rate of combustion of these materials, leading to greater consumer safety. As the use of plastics has increased, the production and use of flame-retardants has also grown. Many BFRs are persistent and have been detected in environmental samples, raising concerns about the biological/toxicological risk associated with their use. Most BFRs appear to be non-toxic, however there is still some concern that these compounds, or possible contaminants in BFRs mixtures could interact with cellular receptors. In this study we have examined the interaction of decabromodiphenyl ether, Firemaster BP4A (tetrabromobisphenol A), Firemaster PHT4 (tetrabromophthalic anhydride), hexabromobenzene, pentabromotoluene, decabromobiphenyl, Firemaster BP-6 (2,2',4,4',5,5'-hexabromobiphenyl) and possible contaminants of BFR mixtures with the Ah receptor. Receptor binding and activation was examined using the Gel Retardation Assay and increased expression of dioxin responsive genes was detected using the reporter gene based CALUX assay. The results demonstrate the ability of BFRs to activate the AhR signal transduction pathway at moderate to high concentrations as assessed using both assays. AhR-dependent activation by BFRs may be due in part to contaminants present in commercial/technical mixtures. This was suggested by our comparative analysis of Firemaster BP-6 versus its primary component 2,2',4,4',5,5'-hexabromobiphenyl. Some technical mixtures of brominated flame-retardants contain brominated biphenyls, dioxins or dibenzofurans as contaminants. When tested in the CALUX assay these compounds were found to be equivalent to, or more active than their chlorinated analogues. Relative effective potency values were determined from dose response curves for these brominated HAHs.

Animals↗

PubMed1988

Applications of the in vitro aryl hydrocarbon hydroxylase induction assay for determining "2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents": pyrolyzed brominated flame retardants.

The pyrolysis of brominated flame retardants FR 300 BA (decabromobiphenyl) ether, FireMaster BP-6 (polybrominated biphenyls), Bromkal 70-5-DE (primarily pentabromodiphenylether), Bromkal 70-DE (primarily penta and tetrabromodiphenylether) and Bromkal G1 (pentabromodiphenylether) resulted in the formation of relatively high levels of polybrominated dibenzofurans (PBDFs) and dibenzo-p-dioxins (PBDDs as determined by gas chromatography-mass spectrometric analysis. The dose response EC50 values for the induction of aryl hydrocarbon hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD) by the flame retardant pyrolysates was determined in rat hepatoma H-4-II E cells and compared to the relative induction activities of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and the concentrations of "2,3,7,8-TCDD equivalents" were calculated. The range of "2,3,7,8-TCDD equivalents" levels (micrograms/g or ppm) derived from values obtained from the AHH and EROD bioassays for each of the pyrolyzed flame retardant samples was: 174-194, 480-1400, 2140-4680, 6740-8780 and 3920-5260 ppm for FR 300 BA, FireMaster BP-6, Bromkal 70 DE, Bromkal 70-5 DE and Bromkal G1, respectively. The in vivo dose-response effects of 2 pyrolyzed flame retardants were determined in immature male Wistar rats and compared to the dose-response activities of 2,3,7,8-TCDD. The in vivo responses which were measured included hepatic microsomal AHH and EROD induction, body weight loss and thymic atrophy. For the pyrolyzed FireMaster BP-6 and Bromkal 70-5 DE samples, the range of calculated in vivo "2,3,7,8-TCDD equivalents" (ppm in sample) for the 4 in vivo bioassays was 520-1780 ppm and 3860-8960 ppm, respectively. The excellent overlap between the in vivo and in vitro 2,3,7,8-TCDD equivalents for the 2 flame retardant pyrolysate extracts supports the utility of the in vitro induction bioassay for quantitatively determining "2,3,7,8-TCDD equivalents" for mixtures containing toxic halogenated aryl hydrocarbons.

Animals↗

PubMed1976

Chemistry and toxicity of flame retardants for plastics.

An overview of commercially used flame retardants is give. The most used flame retardants are illustrated and the seven major markets, which use 96% of all flame-retarded polymers, are described. Annual flame retardant growth rate for each major market is also projected. Toxicity data are reviewed on only those compositions that are considered commercially significant today. This includes 18 compounds or families of compounds and four inherently flame-retarded polymers. Toxicological studies of flame retardants for most synthetic materials are of recent origin and only a few of the compounds have been evaluated in any great detail. Considerable toxicological problems may exist in the manufacturing of some flame retardants, their by-products, and possible decomposition products.

Animals↗

PubMed2003

Are brominated flame retardants endocrine disruptors?

Brominated flame retardants (BFRs) are a group of compounds that have received much attention recently due to their similarity with "old" classes of organohalogenated compounds such as polychlorinated biphenyls (PCBs), in terms of their fate, stability in the environment and accumulation in humans and wildlife. Toxic effects, including teratogenicity, carcinogenicity and neurotoxicity, have been observed for some BFR congeners, in particular the brominated diphenyl ethers (BDEs). This concise review focuses on the potency of BFRs and to disrupt endocrine systems, and attempts to answer the question whether or not BFRs are endocrine disruptors. Evidence is provided on the disruption of the thyroid hormone system by BFRs, with particular emphasis on the BDEs, as most recent data is available on this class of flame retardants. Similar to the hydroxylated PCBs, in vitro mechanistic studies as well as animal experiments have demonstrated the effects of BDEs on thyroid hormone transport and metabolism. An overview of possible effects of BFRs on the estrogen system is also provided. Research gaps are outlined, as well as ongoing and future studies in the European community aimed at contributing to comprehensive risk assessments based on the endocrine-disrupting effects of BFRs.

Animals↗

PubMed1975

Public health implications of components of plastics manufacture. Flame retardants.

The four processes involved in the flammability of materials are described and related to the various flame retardance mechanisms that may operate. Following this the four practical approaches used in improving flame retardance of materials are described. Each approach is illustrated with a number of typical examples of flame retardants or synthetic procedures used. This overview of flammability, flame retardance, and flame retardants used is followed by a more detailed examination of most of the plastics manufactured in the United States during 1973, their consumption patterns, and the primary types of flame retardants used in the flame retardance of the most used plastics. The main types of flame retardants are illustrated with a number of typical commercial examples. Statistical data on flame retardant market size, flame retardant growth in plastics, and price ranges of common flame retardants are presented.

Antimony↗

PubMed2004

Brominated flame retardants: cause for concern?

Brominated flame retardants (BFRs) have routinely been added to consumer products for several decades in a successful effort to reduce fire-related injury and property damage. Recently, concern for this emerging class of chemicals has risen because of the occurrence of several classes of BFRs in the environment and in human biota. The widespread production and use of BFRs; strong evidence of increasing contamination of the environment, wildlife, and people; and limited knowledge of potential effects heighten the importance of identifying emerging issues associated with the use of BFRs. In this article, we briefly review scientific issues associated with the use of tetrabromobisphenol A, hexabromocyclododecane, and three commercial mixtures of polybrominated diphenyl ethers and discuss data gaps. Overall, the toxicology database is very limited; the current literature is incomplete and often conflicting. Available data, however, raise concern over the use of certain classes of brominated flame retardants.

Databases, Factual↗

PubMed2004

A comparison of the fish bioconcentration factors for brominated flame retardants with their nonbrominated analogues.

Flame retardants (FR) play a significant role in reducing the flammability of many consumer products. On a volume basis, approximately 25% of the FRs in use today utilize bromine as the active flame-retarding moiety. Their applications are those requiring high FR performance or in resins needing an FR that is active during the gas phase. Laboratory fish bioconcentration factors (BCFs) for 11 brominated FRs (BFRs) or their components were compared with those for their nonbrominated analogues. Bioconcentration, defined here as a BCF of greater than 1,000, was not observed in those brominated molecules examined with molecular weights of 700 or greater. These included the decabromodiphenyl oxide and octabromodiphenyl oxide commercial products, ethane 1,2-bis(pentabromophenyl), ethylene bis-tetrabromophthalimide, and decabromobiphenyl. Tetrabromobisphenol A, with a molecular weight of less than 700, also did not bioconcentrate. This likely relates to the ease with which it is metabolized and eliminated. Within the BFR class of polybrominated diphenyl oxides/ethers, the BCFs for those congeners with molecular weights of between approximately 450 and 700 varied with the number and position of the bromine atoms. The BCF of hexabromocyclododecane appeared to be related to its cyclododecane substructure, not to its bromine content. Bioconcentration was not a characteristic feature of the BFRs examined here.

Animals↗

PubMed2001

Polybrominated diphenyl ether (PBDE) flame retardants.

Polybrominated diphenyl ether, PBDE, flame retardants are now a world-wide pollution problem reaching even remote areas. They have been found to bioaccumulate and there are concerns over the health effects of exposure to PBDEs, they also have potential endocrine disrupting properties. They are lipophilic compounds so are easily removed from the aqueous environment and are predicted to sorb onto sediments and particulate matter or to fatty tissue, aiding their distribution throughout the environment. PBDEs are structurally similar to PCBs and DDT and, therefore, their chemical properties, persistence and distribution in the environment follow similar patterns. Concentrations of PBDEs found in environmental samples are now higher than those of PCBs. Evidence to date demonstrates that PBDEs are a growing problem in the environment and concern over their fate and effects is warranted. The manufacture of reactive and additive flame retardants is briefly discussed and their fate and behaviour in the environment is assessed. PBDE toxicology is reviewed and methods of analysis are evaluated.

Animals↗

PubMed2005

In vitro estrogenicity of polybrominated flame retardants.

Estrogenicity of five brominated flame retardants (BFRs), namely BDE-47, BDE-99, BDE-205, PBB-153 and technical Firemaster BP-6, were assessed by in vitro assays developed to detect chemicals with estrogenic properties. Recombinant yeast cells containing a human estrogen receptor gene failed to give any response to the chemicals tested. However, the positive control compound, estradiol-17beta, showed that the yeast cell assays had worked properly. The freshly separated fish hepatocyte assay based on the synthesis and secretion of vitellogenin from the isolated liver cells produced a clear dose-response curve in the presence of all tested flame retardants except Firemaster BP-6. The toxicity of the BFRs was detected by determining the cell ethoxyresorufin-O-deethylase activity (EROD). The BFRs tested induced hepatic EROD activity at low test concentrations, but started to inhibit activity at higher concentrations. The decreased detoxification capacity of the hepatocytes resulted in a decrease in the vitellogenin production of the cells. The capability of in vitro assays to detect estrogenic properties of chemicals seems to vary. Thus, further work is needed to understand the mechanisms responsible for these reactions.

Analysis of Variance↗

PubMed2003

Environmental release and behavior of brominated flame retardants.

Recently, environmental problems relating to brominated flame retardants (BFRs) have become a matter of greater concern than ever before, because of the recent marked increase in levels of polybrominated diphenyl ethers (PBDEs) found in human milk in Sweden and North America. The question that arises is whether environmental levels of PBDEs and other BFRs will continue to increase, causing toxic effects to humans. In an attempt to elucidate the current state of the science of BFRs, we review the consumer demand for BFRs (mainly in Japan), the characteristics of waste flame-retarded products, sources of emission, environmental behavior, routes of exposure of humans, temporal trends, and thermal-breakdown products of BFRs. At present, flame-retarded consumer products manufactured 10-20 years ago, when PBDEs were frequently used, are being dumped. The possible major sources of emission of BFRs into the environment are effluent and flue gases from BFR factories and other facilities processing BFRs. With respect to the environmental behavior of BFRs, the lower brominated compounds are, on the whole, predicted to be more volatile, more water soluble, and more bioaccumulative than the higher brominated compounds. The most probable route for exposure of the general human population to PBDEs, especially the lower brominated congeners, is through the diet. The release of BFRs from consumer products treated with these compounds could also lead to human exposure. Temporal trends in PBDE levels in the environment and in humans worldwide seem to vary considerably, depending on the regions or country, with possible reflections of the historic and current use of PBDEs. The environment and the general human population are also exposed to the thermal-breakdown products of PBDEs, such as polybrominated and mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PBDDs/DFs and mixed PXDDs/DFs).

Environmental Exposure↗

PubMedDate not supplied

Analysis of flame retarded polymers and recycling materials.

Recycling activities on polymeric materials are increasing and becoming more and more important in recent years. For polymers containing no flame retardants, suitable recycling strategies already exist. In order to investigate the recyclability of flame retarded polymers that contain brominated flame retardants, a number of samples were analysed as received from a recycling company. Following the identification and sorting of the samples according to type of polymers and flame retardants, material recycling was tested for the flame retarded polymers identified to occur most frequently. The reactivity of the flame retardants during the recycling procedure was studied by analysing for brominated dioxins and furans. The results demonstrate that flame retarded polymers can be recycled under certain experimental conditions.

Bromine↗

PubMed1979

Analytical characteristics of late-eluting halogenated flame retardants.

The analytical characteristics of halogenated flame retardants were studied. Suitable electron capture gas-liquid chromatographic conditions were developed, and retention times and sensitivity responses were obtained. The behavior of these industrial chemicals through the AOAC multiresidue method for nonfatty foods was studied using fish as the test substrate. Of the 24 flame retardants investigated, 23 were recovered (85-110%) using the AOAC method.

Animals↗

PubMed2002

[Flame retardants--use and hazards for human].

Flame retardants (FRs) are chemicals which added to materials during or after manufacture, inhibit or even suppress the combustion process due to their thermal stability. Large quantities of FRs are added to the plastic material (resins) in variety of electrical and electronic appliances including television and computer casing. The other uses of these compounds include production of building materials, upholstered furniture, textiles, wall covering, carpets, hydraulic fluids as well as vehicles and aircraft. Taking into account the chemical structure, there are five main groups of FRs: brominated, chlorinated, phosphorous-containing, nitrogen-containing (i.e. melamines) and inorganic compounds. Halogenated compounds, especially polybrominated diphenyl ethers (PBDEs), a class of brominated flame retardants, due to their lipophilic characteristics and persistence have become ubiquitous environmental contaminants. There are indications that PBDEs may affect hormone function acting as endocrine disruption and may be toxic for developing brain. These compounds have been associated with non-Hodgkin's lymphoma in humans, a variety of cancers in rodents and disruption of thyroid hormones balance. Similarly to other persistent halogenated compounds they are also able to affect the xenobiotic metabolizing enzymes activity. PBDEs are now found as residues in sediments, wildlife and human (milk, serum adipose tissue) samples. The predominant congeners in environmental samples, including human specimens are two congeners: 47 and 99. Currently, the estimated daily intake of PBDEs by adult humans is equal 51 ng x day-1 while by breast-fed infants equals 110 ng x day-1.

Carcinogens↗

PubMed1978

Another flame retardant, tris-(1,3-dichloro-2-propyl)-phosphate, and its expected metabolites are mutagens.

A flame retardant used in children's sleepwear, tris-(1,3-dichloro-2-propyl)phosphate (Fyrol FR2) is a mutagen in the Salmonella-mammalian tissue homogenate test after it has been activated by mouse or rat liver homogenate. The expected enzymatic hydrolysis product, 1,3-dichloro-2-propanol, is similarly a mutagen after activation by liver homogenate. A proposed metabolite of the flame retardant, 1,3-dichloro-2-propanone, is a potent mutagen in the absence of such activation. A flame retardant with similar structure, tris-(2,3-dibromopropyl)phosphate (tris-BP), was shown previously to be a mutagen, to cause sterility in animals, to be a carcinogen, and to be absorbed through human skin. These and other flame retardants have characteristic nuclear magnetic resonance spectra that can be used to determine which flame retardant is present in commercially purchased sleepwear. Sleepwear treated with tris-BP, Fyrol FR2, and other chemical additives was being sold in late 1977.

Animals↗

PubMed2001

Brominated flame retardants in laboratory air.

During the development of a method for determination of brominated flame retardants in human plasma and serum using solid-phase extraction, several brominated flame retardants were found in the procedural blanks. The contaminants originated most probably from the laboratory air. The brominated flame retardants were found to be adsorbed on glass surfaces and to be acquired using solid-phase sampling. 2,4,6-Tribromophenol, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) and 2,2',4,4',5-pentabromodiphenyl ether (BDE-99) were the most abundant brominated flame retardants in our laboratory air, however, large differences in contamination with respect to sampling time and place were observed.

Air Pollution, Indoor↗