Formation of brominated dibenzofurans from pyrolysis of the polybrominated biphenyl fire retardant, firemaster FF-1.

The polybrominated biphenyl (PBB) fire retardant, FireMaster FF-1, was pyrolyzed for 20 min at 380-400 degrees C in open glass tubes and in tubes sealed after nitrogen flushing. The pyrolyzed residue was extracted with benzene, and extracts were cleaned up on columns of graphite (Carbopack A) and alumina. Analysis was carried out by low resolution direct probe mass spectrometry (MS). Spectra from extracts of the open tube pyrolyzed material had a series of ions characteristic of tetra- and pentabrominated dibenzofurans as evidenced by comparison with spectra from 2,3,7,8-tetrabromodibenzofuran (TBDF). Confirmatory evidence for the brominated dibenzofurans was obtained by high resolution MS dual ion analysis of certain fragment and molecular ions. Recovery values of TBDF through the cleanup procedure averaged 50% and, using this recovery value and TBDF as an external standard, dual ion analyses indicated that 40 ppm tetra- and 4 ppm pentabrominanted dibenzofuran were produced based on the PBB level used in the pyrolysis experiments. Additional analysis of the open tube pyrolyzed material by gas chromatography/mass spectrometry provided evidence that there was one tetrabromodibenzofuran compound with a retention time equal to that of TBDF. Trace levels (less than 1 ppm) of the molecular ion of tetrabrominated dibenzofuran were found after analysis by low resolution MS of the PBB pyrolyzed under nitrogen in sealed tubes. The experimental evidence is consistent with a mechanism for brominated dibenzofuran formation involving attack of oxygen on PBB compounds.

Chemical and biological investigations of a transformer accident at Binghamton, NY.

A transformer fire occurred in a state office building in Binghamton, NY on February 5, 1981. Particulates from inside surfaces of ceiling panels on 16 of the 17 floors had concentrations of polychlorinated dibenzofurans (PCDFs) ranging from less than 1 part per million (ppm) to 1200 ppm while polychlorinated biphenyl (PCB) concentrations varied from 28 ppm to 23,000 ppm. In spite of the wide variations in contaminant concentrations, complete analytical data from 11 floors showed that there was a consistent PCDF/PCB ratio (0.067 +/- 0.026) and also consistent PCDF isomer group distributions (tetra-CDFs, 33 +/- 5%; penta-CDFs, 40 +/- 3%; hexa-CDFs, 18 +/- 7%; hepta-CDFs, 6 +/- 3%). It was found that the particulate samples could be successfully ranked in order of their degree of chemical contamination by an in vitro bioassay. The bioassay was based on induction of keratinization or changes in morphology in mouse epithelial cells. Animal toxicology experiments were carried out with a soot sample containing a PCDF concentration which approximated the mean value found on the ceiling particulates. The single dose oral LD values of the soot and its benzene extract equivalent, each administered to female guinea pigs in 0.75% methyl cellulose, were 410 and 327 mg/kg, respectively. These results demonstrated that the soot matrix had virtually no effect on the toxicity of the chemical contaminants in the soot. Morphological alterations in liver tissues from animals receiving the soot were found after examination by electron and light microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiestrogenicity of environmental polycyclic aromatic hydrocarbons in human breast cancer cells.

The total concentration of 14 polycyclic aromatic hydrocarbons (PAHs) was determined to be 3400-fold greater in a sediment sample from an industrial site on the St. Lawrence River (SLR), NY, than in a sediment sample from a non-industrial site on the Kinderhook Creek (KC), NY. PAH fractions from extracts of the two environmental samples and two reconstituted mixtures as well as the 14 individual PAHs were examined for their toxic, estrogenic, and antiestrogenic activities using MCF-7 focus, recombinant human estrogen receptor (ER) binding, whole-cell ER binding, and 17beta-estradiol (E2) metabolism assays. PAH fractions from the KC and SLR were antiestrogenic; they significantly inhibited the formation of foci elicited in MCF-7 breast cancer cells by 1 nM E2. Eight of the 14 individual PAHs, and the reconstituted mixtures were also antiestrogenic. Results from the whole-cell ER binding assay and the radiometric analysis of E2 metabolism indicate that the PAHs detected in the KC and the SLR environmental samples induce antiestrogenic responses in metabolically intact human breast cancer cells through at least two mechanisms: one involving competition for the ER by a PAH metabolite and the other involving depletion of E2 through induction of metabolism.

Separation of extracts from biological tissues into polycyclic aromatic hydrocarbon, polychlorinated biphenyl and polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran fractions prior to analysis.

A low-pressure liquid chromatography method is presented for separating polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDDs/PCDFs) from biological tissue extracts. After removing lipid from extracts, the PAHs are separated from PCBs and PCDDs/PCDFs on a deactivated 13-24 microns silica gel column. The PCBs are subsequently separated from PCDDs/PCDFs by collecting the first fraction from an automated three column cleanup procedure for PCDDs/PCDFs. The complete method has been used to obtain high recoveries of the three compound classes for analysis by GC-electron capture detection (PCBs) or GC-MS (PAHs and PCDDs/PCDFs).

Photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in aqueous solutions and in organic solvents.

Aqueous solutions of selected polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were prepared using a generator column and exposed to UV (300 nm) light in the laboratory and to sunlight in an outdoor environment. In the laboratory, additional exposures were also carried out using 60% acetonitrile/water solutions. At 300 nm di- and tetra PCDDs had higher first-order photodegradation rate constants in 60% acetonitrile/water than in pure water. The solvent effect was reversed for PCDFs. These results may be a reflection of the higher polarity of PCDFs compared to PCDDs. In both the indoor and outdoor exposures photodegradation rates decreased with increasing concentrations of chlorination. However, OCDF exposed to 300 nm light in 60% acetonitrile/water and to sunlight in pure water photodegraded more rapidly than tetra CDF. Photolysis rates in sunlight were considerably slower (t(1/2) of 6.4-23 h) than photolysis rates at 300 nm in the laboratory (t(1/2) of 4.3-680 min), reflecting the lower intensity of sunlight in the 300 nm region of the UV/Vis spectrum. The extent of dechlorination of the PCDDs/PCDFs was less than 20% and reductive dechlorination does not appear to be a major process in the photodegradation of PCDDs/PCDFs in aqueous solutions.

Polychlorinated dibenzofurans and dibenzo-p-dioxins in subsurface soil, superficial dust, and air extracts from a contaminated landfill.

Extracts of soil, dust and air from a National Priorities List Landfill have been found to contain distinct profiles of polychlorinated biphenyls (PCBs). The different extracts show subtle differences in toxicities and the soil extract has been shown to cause both Ah receptor mediated effects and Ah receptor independent effects in immature female rats. Evidence of open burning at the site dictated quantitation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) for a more accurate tabulation of dioxin equivalencies. High volume air sampling on XAD-2 resin cartridges captured trace amounts of PCDFs and no detectable PCDDs. Acetone:Hexane (1:1) extracts of soil and dust contained 762 microg/ml and 250 microg/ml PCDFs, respectively, and less than 10% as much PCDD. Subsequent benzene:methylene chloride (1:1) extracts were enriched in coplanar compounds relative to total PCBs. PCDF:PCB ratios in all extracts were higher than in the rice oils contaminated with heated PCBs in the Yusho and Yu-Cheng incidents. No 2,3,7,8-TCDD was detected, and total PCB+PCDD+PCDF toxic equivalencies were dominated by the high proportions of PCDFs.

Differences in the chromatographic and mass spectral properties of 3,3',5,5'-tetrachlorodiphenoquinone and 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Tetrachlorodiphenoquinones have the same exact mass and elemental composition as the toxic environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin. However, analysis of 3,3'-5,5'-tetrachlorodiphenoquinone showed a pronounced tendency toward chemical reduction in the mass spectrometer to the quinol compound, producing a molecular ion two mass units higher than 2,3,7,8-tetrachlorodibenzo-p-dioxin. Distinct differences were also apparent between the mass spectral fragmentation patterns of 3,3',5,5'-tetrachlorodiphenoquinone and 2,3,7,8-tetrachloridibenzo-p-dioxin. The 3,3',5,5'-tetrachlorodiphenoquinone spectrum shows a successive loss of carbon monoxide, with the most prominent fragment corresponding to loss of two molecules of carbon monoxide plus chlorine. In the mass fragmentation of 2,3,7,8-tetrachlorodibenzo-p-dioxin carbon monoxide loss is suppressed, but loss of one molecule of carbon monoxide plus chlorine is a major fragment ion. During an alumina column clean-up procedure 3,3',5,5'-tetrachlorodiphenoquinone did not coelute with the fraction containing 2,3,7,8-tetrachlorodibenzo-p-dioxin. This evidence indicates that tetrachlorodiphenoquinones are unlikely to interfere with mass spectrometric determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in environmental samples.

Potentiation and antagonism of 2,3,7,8-tetrachlorodibenzo-p-dioxin effects in a complex environmental mixture.

There is increasing need to understand the toxicity of complex environmental mixtures. The organic phase of a leachate (OPL) from the Love Canal chemical dump site is a complex mixture that contains over 100 organic compounds, including 0.74 ppm 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Mice congenic at the Ah locus were used to evaluate several toxic effects of the OPL, including immune function and hepatic enzyme induction. OPL toxicity was compared with that of pure TCDD in both C57BL/6J Ahb/b and congenic C57BL/6 Ahd/d (B6.D2) mice. Mice were given single oral doses of up to 2 g OPL/kg or 100 micrograms TCDD/kg, immunized, and evaluated after 7 days. The TCDD equivalent of the OPL was determined to be 3.9 and 5.0 ppm in C57BL/6J and B6.D2 mice, respectively. This is six times the TCDD content. The Ah phenotype-dependent response ratio was calculated by dividing the dose required to cause an effect in the B6.D2 strain by the dose causing the same effect in the C57BL/6J strain. Ratios based on both ED50s and the lowest observed adverse effect levels were used to determine whether each adverse effect was Ah phenotype-dependent, the extent to which TCDD contributed to the effect, whether there were interactive effects between the AhR ligands and nonligands and if they were additive, antagonistic, or synergistic, and whether the response was predictable based on the known chemical composition of the mixture. It was concluded that the non-TCDD component potentiated TCDD immune suppression, and possibly thymic atrophy, through AhR mechanisms. In contrast, this analysis indicated that the non-TCDD component of the OPL antagonized the ability of the TCDD component to induce hepatic AHH activity whereas OPL hepatomegaly was caused primarily by the non-TCDD component of the OPL. This study demonstrates that the toxicity of mixtures containing TCDD may not be accurately predicted based on the TCDD content alone and that this approach could be useful in the toxicologic assessment and management of environmental contamination.

Neutral cleanup procedure for 2,3,7,8-tetrachlorodibenzo-p-dioxin residues in bovine fat and milk.

A neutral cleanup method for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in milk and animal tissue was developed involving solvent extraction and liquid adsorption chromatography on magnesia-Celite 545, alumina, and Florisil. Cleaned up extracts were subjected to dual-ion analysis in a direct probe high resolution mass spectrometer, interfaced to a multi-channel analyzer for signal averaging. Calibration experiments were carried out with bovine milk and beef fat samples containing added TCDD. The 37CI isotopic isomer of TCDD was added as an internal standard. The response was linear for concentrations in the ppt range, with recoveries about 80%. Milk from a cow fed TCDD was cleaned up by the neutral procedure or, alternatively, a base-acid extraction procedure. The TCDD recoveries for both procedures were essentially the same. Recoveries of TCDD from liver samples of a rat given 14C-TCDD intraperitoneally, subjected to neutral cleanup and radioactive counting, were about 70%.

Subchronic oral toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the guinea pig: comparisons with a PCB-containing transformer fluid pyrolysate.

In contrast to the well-characterized acute toxicity of the environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in the guinea pig, the effects of prolonged po exposure in this species are unknown. The present report describes the results of administration to guinea pigs of 2,3,7,8-TCDD in the feed at levels of 0, 2, 10, 76, or 430 ppt for up to 90 days. Additional aims were to examine recovery following prolonged 2,3,7,8-TCDD exposure in the guinea pig and to generate data to facilitate comparison of the previously reported toxicity of a transformer fluid pyrolysate with that of pure 2,3,7,8-TCDD. Animals receiving 430 ppt 2,3,7,8-TCDD exhibited body weight loss, thymic atrophy, liver enlargement, and 60% mortality by Day 46 (males) and by Day 60 (females), when surviving animals in this group were sacrificed. Total 2,3,7,8-TCDD consumption was approximately 1.3 and 1.9 micrograms/kg, respectively. Animals receiving 76 ppt 2,3,7,8-TCDD for 90 days (total 0.44 microgram/kg) exhibited a decreased rate of body weight gain and increased relative (to body) liver weights. Male animals also displayed a reduction in relative thymus weights and elevated serum triglycerides, while females exhibited hepatocellular cytoplasmic inclusion bodies and lowered serum alanine aminotransferase activities. Toxic effects were generally similar to those observed after acute 2,3,7,8-TCDD administration. No dose-related alterations were seen in animals receiving either 10 ppt (total 0.06 micrograms/kg) or 2 ppt (total 0.01 micrograms/kg) for 90 days, establishing a no-observed-effect level of approximately 0.65 ng 2,3,7,8-TCDD/kg/day. In the recovery study, groups of guinea pigs were administered 430 ppt 2,3,7,8-TCDD for 11, 21, or 35 days and then allowed to recover for an additional 79, 69, or 55 days, respectively. Treatment-related mortality in each group was 0, 10, and 70%, respectively, by Day 90. An effective LD50 of 0.8 microgram 2,3,7,8-TCDD/kg for prolonged exposure was calculated on the basis of these results, a value lower than those previously reported from this laboratory for acute exposure. The results also suggested a possible lowering of the body weight "set point" following 2,3,7,8-TCDD exposure. Comparison of the present findings with those previously reported for a transformer fluid pyrolysate containing a mixture of polychlorinated aromatic species indicated both a greater variety of toxic effects and flatter dose-response relationships for the pyrolysate in the guinea pig.