Paul A. Helm

Sampling in the Great Lakes for pharmaceuticals, personal care products, and endocrine-disrupting substances using the passive polar organic chemical integrative sampler

The passive polar organic chemical integrative sampler in the pharmaceutical configuration (i.e., pharmaceutical-POCIS) was calibrated for sampling at water temperatures of 5, 15 and 25 degrees C to determine the influence of temperature on chemical-specific sampling rates (R(S)), thus providing more robust estimates of the time-weighted average concentrations of pharmaceuticals and personal care products (PPCPs) and endocrine-disrupting substances (EDS) in surface water. The effect of water temperature and flow on the R(S) of these analytes was evaluated in the laboratory with a static system. The loss of the test compounds from water by uptake into POCIS was linear over an 8-d period, and these experimental data yielded R(S) values in the range of 0.07 to 2.46 L/d across the temperature range for the 30 compounds tested. Water temperature and flow influenced POCIS uptake rates, but these effects were relatively small, which is consistent with the theory for uptake into POCIS samplers. Therefore, under a narrow range of water temperatures and flows, it may not be necessary to adjust the R(S) for POCIS. Except for acidic drugs and sulfonamide antibiotics, R(S) values were positively correlated with octanol-water partition coefficients (log K(OW)) of the test compounds. A linear relationship was also observed between R(S) and chromatographic retention times on a C18 reversed-phase column. These observations may provide a rapid method for estimating the R(S) of additional chemicals in the POCIS. The application of the R(S) to POCIS deployed for one month in Lake Ontario, Canada, during the summers of 2006 and 2008 yielded estimates of PPCP and EDS concentrations that are consistent with conventional concentration measurements of these compounds in Lake Ontario surface water.

Brominated and chlorinated flame retardants in Lake Ontario, Canada, lake trout (Salvelinus namaycush) between 1979 and 2004 and possible influences of food-web changes.

Concentrations of non-polybrominated diphenyl ether (PBDE) brominated (hexabromocyclododecane [HBCD], 1,2-bis[2,4,6-tribromophenoxy]ethane [BTBPE], and pentabromoethylbenzene [PEB]) and chlorinated (Dechlorane Plus [DP] as well as short- and medium-chain chlorinated paraffins [SCCP and MCCP, respectively]) flame retardants were evaluated in archived Lake Ontario, Canada, lake trout (Salvelinus namaycush) samples collected between 1979 and 2004. Polybrominated diphenyl ethers also were analyzed to provide a point of reference for comparison to previous studies. Concentrations of the dominant PBDE congeners (BDEs 28, 47, 99, 100, 153, and 154) increased significantly from 1979 until the mid-1990s, then either leveled off or decreased significantly between 1998 and 2004, a result that corresponds to those of previous studies. In contrast, BDE 209 increased approximately fourfold between 1998 and 2004. The temporal trends of the non-PBDE flame retardants varied, with sum (sigma) HBCD and DP showing significant overall decreases; BTBPE, sigmaSCCP, and sigmaMCCP showing parabolic trends; and PEB showing no overall change during the study period. Because many of the non-PBDE chemicals may be used as replacements for penta- and octa-BDE mixtures, these results will provide a baseline to evaluate future usage patterns. Possible changes in food-web structure, evaluated through stable nitrogen isotopes (delta15N), may be influencing our interpretations of contaminant trends in lake trout and are hypothesized to be partially responsible for the observed decrease in concentrations of BDEs 28, 47, 99, 100, 153, and 154 between 1998 and 2004. Retrospective analyses evaluating temporal trends in stable isotope values at the base of the food web, however, are recommended to test this hypothesis further.

Identification and screening analysis of halogenated norbornene flame retardants in the Laurentian Great Lakes: Dechloranes 602, 603, and 604.

Dechlorane (Dec) 602, Dechlorane (Dec) 603, Dechlorane (Dec) 604, and Dechlorane Plus (DP) are flame retardant substitutes for mirex. Dec 602, 603, and 604 were detected in sediment and fish from the Laurentian Great Lakes. Lake Ontario surface sediments had the highest concentrations of Dec 602 and 604 at 6.0 and 4.0 ng/g dry weight, respectively. Temporal analysis of a Lake Ontario sediment core indicates that Dec 602 and 604 trends are similar to DP peaking in the early 1980s. Lake trout and whitefish from Lake Ontario also had the highest concentrations of Dec 602 and 604 at 34 and 1.2 ng/g lipid. Concentrations of Dec 602 were higher than those of DP in all fish samples, indicating that Dec 602 is likely more bioavailable and/or more readily bioaccumulates than DP. Spatial trends for Dec 602 and 604 in sediment and fish indicate that manufacturing plants along the Niagara River upstream of Lake Ontario were important sources of Dec 602 and 604 to the Great Lakes, while Dec 603 in the Great Lakes is likely from atmospheric deposition. The findings of this first report of Dec 602, 603, and 604 in the Laurentian Great Lakes basin suggests further investigation of halogenated norbornene flame retardants in the environment is merited.

The effects of dissolved organic matter and pH on sampling rates for polar organic chemical integrative samplers (POCIS)

The effect of solution pH and levels of dissolved organic matter (DOM) on the sampling rates for model pharmaceuticals and personal care products (PPCPs) and endocrine disrupting substance (EDS) by polar organic chemical integrative samplers (POCIS) was investigated in laboratory experiments. A commercially available POCIS configuration containing neutral Oasis HLB (hydrophilic-lipophilic balance) resin (i.e. pharmaceutical POCIS) and two POCIS configurations prepared in-house containing MAX and MCX anion and cation exchange resins, respectively were tested for uptake of 21 model PPCPs and EDS, including acidic, phenolic, basic and neutral compounds. Laboratory experiments were conducted with dechlorinated tap water over a pH range of 3, 7 and 9. The effects of DOM were studied using natural water from an oligotrophic lake in Ontario, Canada (i.e. Plastic Lake) spiked with different amounts of DOM (the concentration of dissolved organic carbon ranged from 3 to 5mgL(-1) in uptake experiments). In experiments with the commercial (HLB) POCIS, the MCX-POCIS and the MAX-POCIS, the sampling rates generally increased with pH for basic compounds and declined with pH for acidic compounds. However, the sampling rates were relatively constant across the pH range for phenols with high pKa values (i.e. bisphenol A, estrone, estradiol, triclosan) and for the neutral pharmaceutical, carbamazepine. Thus, uptake was greatest when the amount of the neutral species in solution was maximized relative to the ionized species. Although the solution pH affected the uptake of some model ionic compounds, the effect was by less than a factor of 3. There was no significant effect of DOM on sampling rates from Plastic Lake. However, uptake rates in different aqueous matrixes declined in the order of deionized water>Plastic Lake water>dechlorinated tap water, so other parameters must affect uptake into POCIS, although this influence will be minor. MAX-POCIS and MCX-POCIS showed little advantage over the commercial POCIS configuration for monitoring in natural waters.

Passive sampling methods for contaminated sediments: Scientific rationale supporting use of freely dissolved concentrations

Passive sampling methods (PSMs) allow the quantification of the freely dissolved concentration (Cfree) of an organic contaminant even in complex matrices such as sediments. Cfree is directly related to a contaminants chemical activity, which drives spontaneous processes including diffusive uptake into benthic organisms and exchange with the overlying water column. Consequently, Cfree provides a more relevant dose metric than total sediment concentration. Recent developments in PSMs have significantly improved our ability to reliably measure even very low levels of Cfree. Application of PSMs in sediments is preferably conducted in the equilibrium regime, where freely dissolved concentrations in the sediment are well-linked to the measured concentration in the sampler via analyte-specific partition ratios. The equilibrium condition can then be assured by measuring a time series or a single time point using passive samplers with different surface to volume ratios. Sampling in the kinetic regime is also possible and generally involves the application of performance reference compounds for the calibration. Based on previous research on hydrophobic organic contaminants, it is concluded that Cfree allows a direct assessment of 1) contaminant exchange and equilibrium status between sediment and overlying water, 2) benthic bioaccumulation, and 3) potential toxicity to benthic organisms. Thus, the use of PSMs to measure Cfree provides an improved basis for the mechanistic understanding of fate and transport processes in sediments and has the potential to significantly improve risk assessment and management of contaminated sediments. Integr Environ Assess Manag 2014;10:197–209.

PCBs, PBDEs, and PAHs in Toronto air: Spatial and seasonal trends and implications for contaminant transport

The distributions of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Toronto, Canada and the surrounding suburban/rural area were examined. A series of temporally- and spatially-distributed air samples was collected over a 1-year period with a high-volume active air sampler at one downtown site and polyurethane foam passive air samplers at 19 sites. Passive sampler air concentrations of ΣPAHs ranged from 0.27 to 51 ng/m³. Concentrations of ΣPCBs ranged from 6.0 to 1300 pg/m³, and concentrations of ΣPBDEs ranged from 0.47 to 110 pg/m³. All compounds exhibited the highest concentrations in the urban core, and lowest concentrations in the surrounding rural areas, however the exact ratio depended on location since concentrations varied considerably within the city. Results from the application of a radial dilution model highlighted the influence of the central business district (CBD) of the city as a source of contaminants to the surrounding environment, however the radial dilution comparison also demonstrated that sources outside the CBD have a significant influence on regional contaminant concentrations. A strong relationship between temperature and partial pressure of the gas-phase PCBs, low molecular weight PBDEs and less-reactive PAHs suggested that their dominant emissions originated from temperature-controlled processes such as volatilization from local sources of PCBs, PAHs and PBDEs at warm temperatures, condensation and deposition of emissions at cold temperatures, and ventilation of indoor air with elevated concentrations. The relationship between temperature and atmospheric PAH concentrations varied along the urban-rural gradient, which suggested that in highly urbanized areas, such as downtown Toronto, temperature-related processes have a significant impact on air concentrations, whereas winter emissions from domestic heating have a greater influence in areas with less impervious surface coverage.

Compounds Structurally Related to Dechlorane Plus in Sediment and Biota from Lake Ontario (Canada)

The historical occurrence of Dechlorane Plus (DP) and detection of novel compounds structurally related to DP is described in a dated Lake Ontario sediment core. Our core was collected near the mouth of the Niagara River, which is known to be a major source of DP to the lake. Maximum DP concentrations (920 ng g(-1), dry weight) were observed between 1976 and 1980, the highest reported to date. Following that time, we observed a dramatic decrease in DP concentration which coincided with the enactment of United States federal and state laws to mitigate free release of chemicals into the Niagara River and installation of an industrial wastewater treatment facility. During the course of our research, four new substances structurally related to DP were also identified. These compounds were thought to arise from the Diels-Alder reactions resulting from impurities present in 1,5-cyclooctadiene, a feedstock used in production of DP. To confirm our hypothesis, Diels-Alder reactions were performed on the individual impurities. Using different stationary-phase capillary gas chromatography columns and high-resolution mass spectrometry, we were able to positively identify some of these novel compounds in the core. Interestingly, we also were able to identify a monoadduct compound, formed by addition of 1 mol of hexachlorocyclopentadiene to 2 mol of 1,3-cyclooctadiene, in lake trout. The concentration of this monoadduct was approximately 2 orders of magnitude greater than that of DP, suggesting that it is more bioaccumulative.

Historic trends of dechloranes 602, 603, 604, dechlorane plus and other norbornene derivatives and their bioaccumulation potential in lake ontario.

Temporal trends and seasonal variation of Dechloranes (Dec) 602, 603, 604, and Chlordene Plus (CP) in Niagara River suspended sediment, a Lake Ontario sediment core, and Lake Ontario lake trout were investigated, with Mirex and Dechlorane Plus (DP) included for comparison. Temporal concentration trends were generally consistent in each of the media for all compounds with the lowest concentrations observed in or after the late 1990s. In Niagara River suspended sediments, all compounds showed seasonal variation over a year with distinct profiles observed. The relative concentration patterns observed were total DP > Mirex > Dec 602 and Dec 604 > Dec 603 > CP in suspended sediments and sediment cores, whereas Mirex was highest in lake trout, followed by Dec 602 and DP. Dec 602 concentrations were 50 to 380 times greater than those of DP in lake trout, indicating Dec 602 has a greater bioaccumulation potential. The estimated biota-sediment accumulation factor (BSAF) for Dec 602 was much greater than for DP in Lake Ontario, and was greater than those calculated for PBDEs, indicating that assessment of some dechlorane compounds is merited if use is ongoing or planned.

Controlled field evaluation of water flow rate effects on sampling polar organic compounds using polar organic chemical integrative samplers.

The uptake of polar organic contaminants into polar organic chemical integrative samplers (POCIS) varies with environmental factors, such as water flow rate. To evaluate the influence of water flow rate on the uptake of contaminants into POCIS, flow-controlled field experiments were conducted with POCIS deployed in channel systems through which treated sewage effluent flowed at rates between 2.6 and 37 cm/s. Both pharmaceutical POCIS and pesticide POCIS were exposed to effluent for 21 d and evaluated for uptake of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting substances (EDS). The pesticide POCIS had higher uptake rates for PPCPs and EDS than the pharmaceutical POCIS, but there are some practical advantages to using pharmaceutical POCIS. The uptake of contaminants into POCIS increased with flow rate, but these effects were relatively small (i.e., less than twofold) for most of the test compounds. There was no relationship observed between the hydrophobicity (log octanol/water partition coefficient, log K(OW)) of model compounds and the effects of flow rate on the uptake kinetics by POCIS. These data indicate that water flow rate has a relatively minor influence on the accumulation of PPCPs and EDS into POCIS.

Liquid chromatography-atmospheric pressure photoionization tandem mass spectrometry for analysis of 36 halogenated flame retardants in fish.

A comprehensive, sensitive and high-throughput liquid chromatography-atmospheric pressure photoionization tandem mass spectrometry (LC-APPI-MS/MS) method has been developed for analysis of 36 halogenated flame retardants (HFRs). Under the optimized LC conditions, all of the HFRs eluted from the LC column within 14min, while maintaining good chromatographic separation for the isomers. Introduction of the pre-heated dopant to the APPI source decreased the background noise fivefold, which enhanced sensitivity. An empirical equation was proposed to describe the relation between the ion intensity and dopant flow. The excellent on-column instrument detection limits averaged 4.7pg, which was similar to the sensitivity offered by gas chromatography-high-resolution mass spectrometry (GC-HRMS). This method was used to analyze a series of fish samples. Good agreement was found between the results for PBDEs from LC-APPI-MS/MS and GC-HRMS.