F. Reber Brown

Polybrominated diphenyl ethers in residential dust: sources of variability.

We characterized the sources of variability for polybrominated diphenyl ethers (PBDEs) in residential dust and provided guidance for investigators who plan to use residential dust to assess exposure to PBDEs. We collected repeat dust samples from 292 households in the Northern California Childhood Leukemia Study during two sampling rounds (from 2001 to 2007 and during 2010) using household vacuum cleaners and measured 22 PBDEs using high resolution gas chromatography-high resolution mass spectrometry. Median concentrations for individual PBDEs ranged from <0.1-2500ng per g of dust. For each of eight representative PBDEs, we used a random-effects model to apportion total variance into regional variability (0-11%), intra-regional between-household variability (17-50%), within-household variability over time (38-74%), and within-sample variability (0-23%) and we used a mixed-effects model to identify determinants of PBDE levels. Regional differences in PBDE dust levels were associated with residential characteristics that differed by region, including the presence of furniture with exposed or crumbling foam and the recent installation of carpets in the residence. Intra-regional differences between households were associated with neighborhood urban density, racial and ethnic characteristics, and to a lesser extent, income. For some PBDEs, a decreasing time trend explained a modest fraction of the within-household variability; however, most of the within-household variability was unaccounted for by our mixed-effects models. Our findings indicate that it may be feasible to use residential dust for retrospective assessment of PBDE exposures in studies of childrens health (e.g., the Northern California Childhood Leukemia Study).

High concentrations of polybrominated diphenylethers (PBDEs) in breast adipose tissue of California women.

We measured major PBDEs and PCBs in breast adipose tissues of California women participating in a breast cancer study in the late 1990s. Samples were analyzed using gas chromatography with electron impact ionization and tandem mass spectrometry detection. The congener profile observed was: BDE47>BDE99>BDE153>BDE100>BDE154 and PCB153>PCB180>PCB138>PCB118. Whereas high correlations were observed within each chemical class, very weak correlations appeared between classes, pointing to different exposure pathways. Weak negative associations were observed for PBDE congeners and age. Our PBDE data are among the highest reported, exceeding data from the National Health and Nutrition Examination Survey and consistent with the high use of PBDEs in California. These data may be helpful in establishing a baseline for PBDE body burdens to gauge changes over time as a result of restrictions in the use of PBDE formulations.

Levels of Non-Polybrominated Diphenyl Ether Brominated Flame Retardants in Residential House Dust Samples and Fire Station Dust Samples in California

Eleven novel brominated flame retardants (NBFRs) were analyzed in dust samples from California homes as a part of the Northern California Childhood Leukemia Study (NCCLS) and from the living quarters of California fire stations as a part of the Firefighter Occupational Exposure (FOX) study using high resolution gas chromatography/mass spectrometry. The eleven NBFRs were α- and β-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (α- and β-DBE-DBCH), 2-bromoallyl 2,3,6-tribromophenylether (BATE), pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), 2,3-dibromopropyl 2,4,6-tribromophenyl ether (TBP-DBPE), hexabromobenzene (HBB), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP), and decabromodiphenylethane (DBDPE). Six of the seven NBFRs that are produced in relatively small quantities (i.e., α-, β-DBE-DBCH, BATE, PBEB, PBT, TBP-DBPE) were measured close to or below the limit of quantitation (0.64 ng/g) in both the NCCLS and FOX samples, and the seventh, HBB, was measured at median concentrations of 1.85 ng/g and 9.40 ng/g in the NCCLS and FOX samples, respectively. The remaining four NBFRs, EH-TBB, BEH-TEBP, BTBPE, and DBDPE, are produced in higher quantities, and were detected at median concentrations of 337 ng/g, 186 ng/g, 22.3 ng/g, and 82.8 ng/g, respectively in the NCCLS samples, and at median concentrations of 2687 ng/g, 2076 ng/g, 28.4 ng/g, and 161 ng/g, respectively, in the FOX samples. Concentrations of NBFRs in the NCCLS and FOX dust samples were several times lower than concentrations of PBDEs previously measured in the same samples. Concentrations of NBFRs in the NCCLS and FOX dust samples were generally comparable to concentrations of NBFRs in other studies of house dust from the US and Canada.

Polychlorinated biphenyls in residential dust: sources of variability.

We characterized the variability in concentrations of polychlorinated biphenyls (PCBs) measured in residential dust. Vacuum cleaner samples were collected from 289 homes in the California Childhood Leukemia Study during two sampling rounds from 2001 to 2010 and 15 PCBs were measured by high resolution gas chromatography-mass spectrometry. Median concentrations of the most abundant PCBs (i.e., PCBs 28, 52, 101, 105, 118, 138, 153, and 180) ranged from 1.0-5.8 ng per g of dust in the first sampling round and from 0.8-3.4 ng/g in the second sampling round. For each of these eight PCBs, we used a random-effects model to apportion total variation into regional variability (6-11%), intraregional between-home variability (27-56%), within-home variability over time (18-52%), and within-sample variability (9-16%). In mixed-effects models, differences in PCB concentrations between homes were explained by home age, with older homes having higher PCB levels. Differences in PCB concentrations within homes were explained by decreasing time trends. Estimated half-lives ranged from 5-18 years, indicating that PCBs are removed very slowly from the indoor environment. Our findings suggest that it may be feasible to use residential dust for retrospective assessment of PCB exposures in studies of childrens health.

High Levels of Polybrominated Diphenyl Ethers in Vacuum Cleaner Dust from California Fire Stations

Firefighters are exposed to chemicals during fire events and may also experience chemical exposure in their fire stations. Dust samples from used vacuum cleaner bags were collected from 20 fire stations in California and analyzed for polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) using gas chromatography-mass spectrometry. Median dust concentrations were higher for PBDEs (e.g., 47 000 ng/g for BDE-209) than for PAHs (e.g., 220 ng/g for benzo[a]pyrene) or PCBs (e.g., 9.3 ng/g for PCB-180). BDE-209 concentrations in dust from California fire stations were among the highest of any previously documented homes or occupational settings in the world. We examined factors such as the frequency of emergency responses, the number of fire vehicles on site, and building age, but we could not account for the high levels of BDE-209 observed in fire station dust. Based on the findings of our pilot study, we hypothesize that possible sources of BDE-209 in fire stations include contaminated ash tracked back from fire events via boots, clothing, and other equipment as well as specialized equipment treated with BDE-209, including turnout gear and fire vehicles. We suggest possible follow-up studies to confirm these hypotheses.

Separation of phenols and their glucuronide and sulfate conjugates by anion-exchange liquid chromatography

Improved methods are needed for both separation and detection of polar, foreign compound metabolites in biological tissues and fluids. The most important mammalian conjugation reactions involve attachment of glucuronide and sulfate moieties, with glucuronidation predominating’*‘. Accordingly, our method development efforts have been focused on these two conjugate classes. Gas chromatography (GC) and GC-mass spectrometry (MS) have been used to measure glucuronides, but isolation and derivatization are necessary3. Sulfate conjugates are generally hydrolized by acid or enzymatically, followed by analysis of the non-polar hydrolysis product3. The use of high-performance liquid chromatography (HPLC) offers the potential for the direct determination of sulfate and glucuronide conjugates with little or no sample preparation. Various HPLC methods for these compounds have been published, most of these based on ion-pair reversed-phase chromatographic systems6lo. In each of these reports, the authors separated either a single phenol and its glucuronide and sulfate, or the sulfate or glucuronide conjugates of several different phenols. In contrast, the present paper describes the simultaneous separation of three phenols and their respective glucuronide and sulfate conjugates using a strong anion-exchange chromatographic column and an ammonium formate buffer, an application that has not previously been reported.

Chlorine-Selective Detection in Supercritical Fluid Chromatography using a Coulson Electrolytic Conductivity Detector

Abstract A Coulson electrolytic conductivity detector has been coupled successfully to a supercritical fluid chromatograph, providing chlorine-selective detection. This involves minimal modification of the detector and no modification of the SFC or its operation. The general operating parameters of the SFC/CECD system were established by direct injection of three probe compounds: chlordane, γ-lindane, and hexachlorobenzene. Next, the SFC separation of a test mixture containing phenol, γ-lindane, and several chlorinated phenols and related compounds was optimized using UV-Vis and FID detection. The mixture was then separated using the same chromatographic method but with the CECD in line with the UV-Vis detector. The response of the CECD was linear and selective for chlorinated compounds. Limits of detection for the test mixture by CECD ranged from 80 – 250 ng/μL, corresponding to approximately 14 – 44 ng of chlorine on column, and were dependent on chromatographic conditions, but independent of analyte st...

Organophosphate flame retardants in dust collected from United States fire stations

Firefighters are exposed to chemicals during fire events and we previously demonstrated that fire station dust has high levels of polybrominated diphenyl ethers (PBDEs). In conducting the Fire Station Dust Study, we sought to further characterize the chemicals to which firefighters could be exposed - measuring the emerging class of phosphorous-containing flame retardants (PFRs) in fire stations, for the first time, as well as PBDEs. Dust samples from 26 fire stations in five states were collected from vacuum-cleaner bags and analyzed for PFRs and PBDEs. PFR concentrations were found to be on the same order of magnitude as PBDE concentrations (maximum PFR: 218,000ng/g; maximum PBDE: 351,000ng/g). Median concentrations of tri-n-butyl phosphate (TNBP), tris (2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl)phosphate (TDCIPP) in dust from fire stations were higher than those previously reported in homes and other occupational settings around the world. Total PFR levels did not vary significantly among states. Levels of TDCIPP were higher in stations where vacuum cleaners were used to clean surfaces other than the floor. PBDE levels were comparable to those found in our previous study of 20 California fire stations and much higher than levels in California residences. PFR and PBDE levels in fire station dust are higher than in other occupational and residential settings, underscoring the need to identify and control sources of this contamination.

Evaluation and Application of Supercritical Fluid Chromatography with Electrolytic Conductivity Detection

Abstract An electrolytic conductivity detector (ElCD) designed for use with capillary GC columns has been coupled with a capillary supercritical fluid chromatograph (SFC). Detector gas and solvent flows were optimized for use with the capillary SFC system. When used with a large-volume (1 μL) injection technique, the limit of detection for the system is 0.25–5.0 ng/μL for most of the compounds studied, corresponding to 0.2–2 ng of chlorine injected, depending on the degree of chlorination of the compound. Calibration curves are linear to an upper range of 50–80 ng/μL of target compound. Soil samples spiked with mixtures of seven chlorinated phenols were analyzed by this SFCElCD system and the results were compared with those obtained by GC-ECD.