Marta Venier

2-Ethylhexyl Tetrabromobenzoate and Bis(2-ethylhexyl) Tetrabromophthalate Flame Retardants in the Great Lakes Atmosphere

Two relatively new flame retardants, 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) and bis(2-ethylhexyl)-tetrabromophthalate (TBPH), were identified and quantitated in gas and particle-phase air samples collected from six sites near the shores of the Great Lakes. TBB and TBPH were detected in more than half of the samples collected from 2008 to 2010. Urban areas, such as Chicago and Cleveland, showed the highest concentrations (0.36-290 pg/m(3)), while remote areas, such as Eagle Harbor and Sleeping Bear Dunes, exhibited the lowest levels (0.050-32 pg/m(3)). The atmospheric concentrations of TBB and TBPH increased rapidly and significantly over this time period, perhaps indicating that these compounds are replacing the polybrominated diphenyl ethers (PBDEs), which have been removed or soon will be removed from the marketplace.

Time Trend Analysis of Atmospheric POPs Concentrations in the Great Lakes Region Since 1990

Using a multiple linear regression model of the concentrations of several persistent organic pollutants in the atmospheric vapor and particle phases and in precipitation, we have analyzed a data set of about 700,000 values to determine the rate at which these concentrations are decreasing. These concentrations were measured as part of the Integrated Atmospheric Deposition Network (IADN), which has operated several sites near the North American Great Lakes since 1991. The pollutants measured include 83 polychlorinated biphenyl congeners, 17 polycyclic aromatic hydrocarbons, and 24 organochlorine pesticides. In the approach used here, for each of the three phases, the concentrations of a specific chemical at all the sites were combined and fitted with a regression incorporating the sine and cosine of the Julian Day (relative to 1 January 1990 and with a periodicity of one year) and the population living and working within a 25-km radius of the sampling site. Partial residuals were then calculated for each datum, all of the residuals for the three phases were combined, and an overall halving time was calculated from them. This relatively simple approach indicated that the concentrations of PCBs in air around the Great Lakes are decreasing with an overall halving time of 17 ± 2 years, which is slow for a substance that was banned about 35 years ago. Phenanthrene, chrysene, and endosulfan showed halving times on the order of 10 years. The concentrations of several organochlorine pesticides were decreasing more rapidly; for example α- and γ-HCH (lindane) have halving times of about 3.5 years.

Chicago's Sanitary and Ship Canal sediment: Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, brominated flame retardants, and organophosphate esters.

The Chicago Sanitary and Ship Canal (CSSC) links the Great Lakes to the Mississippi River starting in downtown Chicago. In addition to storm water, the CSSC receives water from Chicagos wastewater treatment plants (WWTP). Such effluents are known to be sources of organic pollutants to water and sediment. Therefore in 2013, we collected 10 sediment samples from the CSSC and measured the concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), brominated flame retardants, and organophosphate esters (OPEs). Geometric mean concentrations of the summed concentrations of 16 PAHs ranged from 11,000 to 420,000 ng/g dw, with the highest concentrations located at each end of the canal. Total PCB concentrations had a geometric mean of 1,400 ± 500 ng/g dw. Brominated flame retardants were separated into two groups: polybrominated diphenyl ethers (PBDEs) and non-PBDEs. Concentrations of PBDEs and those of the non-PBDE flame retardants had a geometric average of 83 ± 19 and 7.0 ± 5.8 ng/g dw, respectively. The summed concentrations of 8 OPEs ranged from 470 to 2,800 ng/g dw, with the highest concentration detected at a site located downstream of the Stickney water reclamation plant. Using ANOVA results, some hypotheses on sources to the CSSC could be formulated: downtown Chicago is probably a source of PAHs, the Cal-Sag Channel may be a source of PCBs, and neither the WWTP nor the Cal-Sag Channel seem to be significant sources of brominated flame retardants or OPEs.

Tribromophenoxy flame retardants in the Great Lakes atmosphere.

The 2,4,6-tribromophenoxy moiety is a common structural feature of several brominated flame retardants, and we have previously reported on the environmental concentrations of one such compound, 1,2-bis(2,4,6-tribromophenoxy) ethane (TBE). Here we report the atmospheric concentrations of TBE and three other tribromophenoxy compounds: allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), and 2,3-dibromopropyl 2,4,6-tribromophenyl ether (DPTE). The samples were collected at five sites near the shores of the Great Lakes during the period 2008-2009, inclusive. Of these four compounds, TBE and ATE are currently used as flame retardants, and DPTE was formerly used as a flame retardant until its production ceased in the mid-1980s. The total concentrations of ATE, BATE, and DPTE were ∼2 pg/m³ in the cities of Chicago and Cleveland and 0.1-0.4 pg/m³ at the rural and remote sites. The concentrations of TBE were ∼1 pg/m³ in these cities and 0.2-0.8 pg/m³ at the rural and remote sites. In both cases, this was a very significant urban effect. The concentrations of ATE, BATE, and DPTE did not change significantly over the two-year study, but the concentrations of TBE decreased by about a factor of 2 during this time. This temporal change was statistically significant but not strong compared to the urban effect.

Trends in the levels of halogenated flame retardants in the Great Lakes atmosphere over the period 2005-2013.

Air (vapor and particle phase) samples were collected every 12days at five sites near the North American Great Lakes from 1 January 2005 to 31 December 2013 as a part of the Integrated Atmospheric Deposition Network (IADN). The concentrations of 35 polybrominated diphenyl ethers (PBDEs) and eight other halogenated flame retardants were measured in each of the ~1,300 samples. The levels of almost all of these flame retardants, except for pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), and Dechlorane Plus (DP), were significantly higher in Chicago, Cleveland, and Sturgeon Point. The concentrations of PBEB and HBB were relatively high at Eagle Harbor and Sturgeon Point, respectively, and the concentrations of DP were relatively high at Cleveland and Sturgeon Point, the two sites closest to this compounds production site. The data were analyzed using a multiple linear regression model to determine significant temporal trends in these atmospheric concentrations. The concentrations of PBDEs were decreasing at the urban sites, Chicago and Cleveland, but were generally unchanging at the remote sites, Sleeping Bear Dunes and Eagle Harbor. The concentrations of PBEB were decreasing at almost all sites except for Eagle Harbor, where the highest PBEB levels were observed. HBB concentrations were decreasing at all sites except for Sturgeon Point, where HBB levels were the highest. DP concentrations were increasing with doubling times of 3-9years at all sites except those closest to its source (Cleveland and Sturgeon Point). The levels of 1,2-bis(2,4,6-tribromophenoxy)ethane (TBE) were unchanging at the urban sites, Chicago and Cleveland, but decreasing at the suburban and remote sites, Sturgeon Point and Eagle Harbor. The atmospheric concentrations of 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB) and bis(2-ethylhexyl)-tetrabromophthalate (BEHTBP) were increasing at almost every site with doubling times of 3-6years.

Flame Retardants in the Serum of Pet Dogs and in Their Food

A previous study from our laboratory showed that pet cats had much higher serum levels of flame retardants compared to humans, despite sharing the same household environment. Dogs, on the other hand, are expected to have lower serum levels of flame retardants because they are metabolically better equipped to degrade these compounds. Thus, we hypothesized that dogs might be more similar to humans in their response to these environmental stressors and be better indicators of human exposures to these contaminants. Serum samples and their food were collected from 18 dogs and analyzed for PBDEs and other emerging flame retardants. The concentrations of PBDEs in dog serum and dog food averaged 1.8 ± 0.4 ng/g wet weight (ww) and 1.1 ± 0.2 ng/g ww, respectively. While the dog serum samples were dominated by the tetra to hepta BDE congeners, BDE-209 was the most abundant congener in the dog food. This difference in congener pattern was analyzed in terms of half-lives. Assuming food as the main exposure source, the average half-life in dog serum was 450 ± 170 days for the less brominated congeners and 2.3 ± 0.5 days for BDE-209. Dust was also considered as an additional exposure source, giving unreasonable residence times. In addition to PBDEs, other flame retardants, including Dechlorane Plus, decabromodiphenylethane, and hexabromocyclododecane, were identified in these samples.

Temporal Trends of Persistent Organic Pollutants: A Comparison of Different Time Series Models

We analyzed the vapor phase atmospheric concentrations of representative persistent chemicals (i.e., α- and γ-hexachlorocyclohexane, phenanthrene, PCB-18 and PCB-52) in samples collected at a remote site near Eagle Harbor, Michigan, and at an urban site in Chicago, Illinois, using four time series models: a modified Clausius-Clapeyron equation, a multiple linear regression that includes both a linear and an harmonic dependence on time, digital filtration (DF), and dynamic harmonic regression (DHR). The results of these different models were evaluated in terms of goodness-of-fit, long-term trends, and halving times. The four approaches all provided highly significant descriptions of the data, with coefficients of determination (R(2)) ranging from 0.33 to 0.96. In general, the DF and DHR methods fit the data better, capturing not only the seasonal variations of the atmospheric concentrations but also smaller scale interannual variations in the long term trends. The halving times calculated using the four methods were generally similar to one another, and they ranged from about 4 years for γ-HCH at Chicago to about 60 years for PCB-52 at Chicago. This analysis showed that each of these four statistical methods for evaluating long-term time series has advantages and disadvantages. The choice of the appropriate method should depend on the output needed, the type of audience, and the availability and usability of the necessary software.

Regression model of partial pressures of PCBs, PAHs, and organochlorine pesticides in the Great Lakes' atmosphere.

The gas-phase concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides have been measured at six sites around the Great Lakes every 12 days since the early 1990s as part of the Integrated Atmospheric Deposition Network. After converting the concentrations into partial pressures, data from all of the sites were combined and fitted using a multiple linear regression equation that included time (indicating the effect of a chemicals regulation), atmospheric temperature (indicating seasonality of use or release), the human population within a 25 km radius of the site (indicating the effect of urbanization) and wind speed and wind direction (indicating the source of the chemical). The atmospheric levels of lindane (gamma-HCH), DDTs, endosulfans, and chlordanes were largely related to seasonality, with much higher levels in the warm summer months. The levels of SigmaPCBs, SigmaPAHs, SigmaDDTs, and chlordanes were related to urbanization (this was a secondary factor for the latter two), a result that was unexpected for the two pesticides. The levels of only two compounds, alpha- and gamma-HCH, decreased rapidly as a function of time; conversely, most other compounds are declining at much slower rates. Wind speed and wind direction were statistically significant but unimportant variables for most of the compounds.

Differences in spatiotemporal variations of atmospheric PAH levels between North America and Europe: data from two air monitoring projects.

Atmospheric concentrations of high molecular weight polycyclic aromatic hydrocarbons (PAHs) were measured at five sites for almost two decades near the North American Great Lakes, as part of the Integrated Atmospheric Deposition Network (IADN), and at three remote sites around Europe, as part of the European Monitoring and Evaluation Programme (EMEP). The primary objectives were to reveal the spatial distributions, long-term temporal trends, and seasonal variations of atmospheric PAH concentrations and to investigate potential differences between these two regions. Atmospheric PAH concentrations at the urban sites in Chicago and Cleveland near Great Lakes were about 20 times (depending on PAH congener and sampling site) greater than those at the rural sites except for Košetice in the Czech Republic. Atmospheric PAH concentrations at Košetice, also a rural site, were about one-third of those at Chicago and Cleveland, but 10 times higher than those at other rural sites (Sturgeon Point, Sleeping Bear Dunes, Eagle Harbor, Aspvreten, and Spitsbergen). Significant long-term decreasing trends of all these PAH atmospheric concentrations were observed at Chicago and Cleveland. For the other sites, either less significant or no long-term decreasing trends were observed. Clear seasonality was observed at Sturgeon Point, Sleeping Bear Dunes, Košetice, and Spitsbergen, with the highest PAH concentrations observed in mid-January.

Bioaccumulation of Dechloranes, organophosphate esters, and other flame retardants in Great Lakes fish

We measured the concentrations of 60 flame retardants (and related compounds) in fish samples collected in the Great Lakes basin. These analytes include dechlorane-related compounds (Decs), organophosphate esters (OPEs), and brominated flame retardants (BFRs). Composite lake trout (Salvelinus namaycush) or walleye (Sander vitreus, from Lake Erie) samples were collected (N=3 for each lake) in 2010 from each of the five Great Lakes (a total of 15 samples). Among the dechlorane-related compounds, Dechlorane, Dechlorane Plus, Dechlorane-602, Dechlorane-603, and Dechlorane-604 (with zero to three bromines and with four chlorines) were detected in >73% of the fish samples. The concentrations of some of these dechlorane-related compounds were 3-10 times higher in Lake Ontario trout than in fish from the other four lakes. Tris(1-chloroisopropyl) phosphate, tri-n-butylphosphate, tris(2-chloroethyl)phosphate, and triphenyl phosphate were found in >50% of the fish samples. Polybrominated diphenyl ethers (PBDEs) were the most abundant of the flame retardants in fish, with a mean concentration of 250ng/g lipid. Our findings suggest that the Decs and BFRs with 3-6 bromines are more bioaccumulative in the fish than the OPEs and high molecular weight BFRs.