Enhanced pressurized liquid extraction technique capable of analyzing polychlorodibenzo-p-dioxins, polychlorodibenzofurans, and polychlorobiphenyls in fish tissue

Application of a ready-to-use cell sensor for dioxins and dioxin-like compounds screening in foodstuffs

Dioxins and dioxin-like compounds (DLCs) in foodstuffs are closely related to human health. As China is the largest food-consuming country, there is a potentially large demand for screening bioassays that are rapid, cost-effective and capable of determining dioxins and DLCs in foodstuffs. CBG2.8D is a reporter gene-based recombinant cell sensor that was recently developed for determining dioxin and DLCs in ambient and seafood samples. In this study, we established a bioanalytical method with this ready-to-use cell sensor for the bioanalysis of dioxins and DLCs in different types of meat samples. Twenty-nine samples from three typical types of meat (beef, pork and fish) were collected and subjected to both instrumental analysis and a CBG2.8D bioassay. The intra- and inter-lab reproducibility of the bioassay was investigated and the coefficients of variation (CVs) were lower than 25%, suggesting that the cell sensor had a good reproducibility for the meat samples. Based on the correlation equation and coefficient obtained by comparing the data from the instrumental analysis and CBG2.8D bioassay, we found that this method had better performance with pork and fish than with beef. The compliance rate was also determined by comparing the results from the instrumental analysis and there were no false results for the pork and fish samples. Lastly, a complete operation procedure was summarized as a guideline for practical application. In conclusion, the CBG2.8D cell sensor exhibits excellent stability and is capable of screening dioxins and DLCs in meat samples.

Method Development and Determination of Chlorinated Polycyclic Aromatic Hydrocarbons in Different Matrices

The aim of this study was to develop an analytical method, which separates selected chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) from fat, and fat-free or vegetable matrices. The method contains extraction-, cleanup-, and quantification steps. Integration of automated analysis actions, as in extraction and cleanup, should enhance the reproducibility, precision, and efficiency of the method. This was confirmed by validation of the overall analytical process. In the end, as a performance check, the developed method was applied on different matrices, e.g., tea, rice, grilled pork, and eel and predator eggs, as a non-food example. An inter-laboratory check was initiated as replacement for the lack of proficiency tests. Due to the high level of automation, both personnel and time effort are very low. In addition, the method is very robust with regard to the variability of the solvent selection and the loss of analytes by evaporation to dryness. It could be demonstrated that the developed method is applicable to different matrices with reproducible and precise results. This applies also to low-fat food and feed.

Oxidative Potential of Chemical Mixtures Extracted from Contaminated Galveston Bay, TX Seafood Using a Human Cell Co-culture Model

Increasing levels of pollution in Galveston Bay, TX, are of significant concern for populations that directly depend on fishing activities. Efforts to evaluate contaminant levels in commercial fish have been largely limited to the quantification of chemical mixtures in fish tissue, but little information exists about the toxicological potential of these chemicals on consumption of contaminated seafood. The present study makes use of a human cell co-culture model, mimicking the digestive system, to address the oxidative potential of chemical mixtures in seafood. Chemical extractions were performed on fillets from three fish species and oysters collected from different areas in Galveston Bay. The resulting extracts were used to expose intestinal and liver cells before the measurement of cytotoxicity and activity of antioxidant enzymes. The pesticide 4,4'-DDE was found in nearly all samples from all sites in concentrations ranging from 0.23-9.4 µg/kg. Similarly, total PCBs found in fish and oyster tissue ranged from 0.68-65.65 µg/kg, with PCB-118 being the most common congener measured. In terms of cytotoxicity, oyster extracts led to significant cell mortality, contrary to observations for fish extracts. Antioxidant enzymes, while not directly related to the presence of chemical mixtures in tissue, presented evidence of potential increases in activity from spotted trout extracts. Observations from this study suggest the need to evaluate toxicological aspects of contaminated seafood and support the use of in vitro models for the screening of accumulated chemicals.

Applicability of a human cell co-culture model to evaluate antioxidant responses triggered by chemical mixtures in fish and oyster homogenates

The accumulation of chemical compounds in fish tissue represents significant health concerns for seafood consumers, but little is known about the risks to human health associated with such substances. The identification of adverse biological responses upon exposure to contaminants has been facilitated by the development of in vitro systems resembling the human dietary pathway. The present study explores the applicability of an organotypic co-culture system, using intestinal (Caco-2) and hepatic (HepaRG) cell lines, to provide insight into the toxicity of chemical mixtures found in commercially available seafood. Chemical extractions were conducted utilizing fish and oyster standard reference material (SRM) from the U.S. National Institute of Standards and Technology (NIST). Cells were seeded in monoculture and co-culture systems and exposed to SRM extracts before measurements of cytotoxicity and antioxidant responses. Exposure to oyster extracts led to significant cell mortality in monocultures. HepaRG cells in monoculture expressed lower levels of glutathione peroxidase and superoxide dismutase than HepaRG cells in co-culture, upon exposure to both oyster and fish extracts. These observations illustrate the importance of organotypic co-culture models to explore biological responses that could be otherwise difficult to evaluate in monocultures, and the adverse effects associated with the consumption of contaminated seafood.

Polychlorinated biphenyl tissue-concentration thresholds for survival, growth, and reproduction in fish

Polychlorinated biphenyls (PCBs) have left a legacy of environmental contamination. Even though they were banned from production and active use in the 1970s, they persist in the environment and still have the potential to impact aquatic life. Our objective was to identify data from controlled laboratory studies of PCB-related adverse effects in fish and to conduct a meta-analysis on mortality, growth, and reproductive (MGR) threshold responses. For each endpoint type, we compiled data on the lowest-observed-adverse effect concentration (LOAEC) and the degree of effect at the LOAEC as a percentage of control. The LOAECs were expressed as tissue concentrations, so the term lowest-observed-adverse-effect residue concentration (LOAER) was used to represent PCB exposures. The lower limit of applicability was set at 0.1 μg/g total PCB tissue concentration, below which adverse MGR effects in fish were not supported by the data. Sensitivity distributions identifying the probability of adverse effects in fish populations or communities predicted that 25% of fish species would be impacted between 0.1 and 7.5 μg/g. Concentration-response threshold regressions were developed from the MGR datasets. For example, a 1 μg/g total PCB tissue concentration would predict effects of 17% mortality, 15% growth, and 39% reproductive. The analysis determined the degree of adverse response, with uncertainty estimates, expected across a broad range of PCB tissue exposure concentrations in fish. Data generated from MGR endpoints were combined to determine an approach for overall effect thresholds for PCB-related injury in fish. The MGR datasets included only laboratory data; however, responses were compared with field-observed effects. The present review provides a comprehensive assessment of PCB-induced injury in fish utilizing a data-inclusive approach. Environ Toxicol Chem 2019;38:712-736. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Polychlorinated biphenyl (PCB) contamination in Galveston Bay, Texas: Comparing concentrations and profiles in sediments, passive samplers, and fish

The industrialized portion of the Houston Ship Channel (HSC) is heavily contaminated with anthropogenic contaminants, most prominent of which are the polychlorinated biphenyls (PCBs). This contamination has driven adaptive evolution in a keystone species for Galveston Bay, the Gulf killifish (Fundulus grandis). We investigated the geographical extent of PCB impacts by sampling 12 sites, ranging from the heavily industrialized upper portion of the HSC to Galveston Island. At each site, PCB concentrations and profiles were determined in three environmental compartments: sediment, water (polyethylene passive samplers), and fish tissue (resident Gulf killifish). We observed a steep gradient of PCB contamination, ranging from 4.00 to 100,000 ng/g organic carbon in sediment, 290-110,000 ng/g lipid in fish, and 4.5-2300 ng/g polyethylene in passive samplers. The PCB congener profiles in Gulf killifish at the most heavily contaminated sites were shifted toward the higher chlorinated PCBs and were highly similar to the sediment contamination profiles. In addition, while magnitude of total PCB concentrations in sediment and total fish contamination levels were highly correlated between sites, the relative PCB congener profiles in fish and passive samplers were more alike. This strong correlation, along with a lack of dependency of biota-sediment accumulation factors with total contamination rates, confirm the likely non-migratory nature of Gulf killifish and suggest their contamination levels are a good site-specific indicator of contamination in the Galveston Bay area. The spatial gradient of PCB contamination in Galveston Bay was evident in all three matrices studied and was observed effectively using Gulf killifish contamination as an environmentally relevant bioindicator of localized contamination in this environment.

Fast extraction of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran in sewage sludge and soil samples

The current environmental legislations recommend monitoring chemical contaminants such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans before the use of sewage sludge on the agricultural land. In this study, a solid-liquid extraction with low-temperature purification (SLE-LTP) was optimized and validated to determine 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in sewage sludge and soil samples. The analyses were performed by gas chromatography-mass spectrometry operating in the selective ion mode (GC-MS-SIM). Acetonitrile:ethyl acetate 6.5:1.5 (v/v) was the best extraction phase, and the recoveries percentages were close to 100%. The linearity was demonstrated in the range of 1.25-25 µg L^-1 of 1.25-20 µg L^-1 for sewage sludge and soil, respectively. Matrix effect was proved for the two compounds and in the two matrices studied. Extraction percentages were between 78 and 109% and relative standard deviations ≤ 19%. The proposed method is faster than methods described in the literature because showed a few steps. The quantification limits (LOQ) in sewage sludge were 6.4 and 32 ng TEQ kg^-1 for 2,3,7,8-TCDF and 2,3,7,8-TCDD, respectively. In soil, LOQs were 0.8 and 8.0 ng TEQ kg^-1 for 2,3,7,8-TCDF and 2,3,7,8-TCDD, respectively. These values are lower than the maximum residue limits established by European Legislation. The method was applied to 22 agricultural soil samples from different Brazilian cities and 2,3,7,8-TCDF was detected in one of these samples.

Occurrence of Triclocarban and Triclosan in an Agro-ecosystem Following Application of Biosolids

Triclocarban (TCC) and triclosan (TCS), two of the most commonly used antimicrobial compounds, can be introduced into ecosystems by applying wastewater treatment plant biosolids to agricultural fields. Concentrations of TCC and TCS were measured in different trophic levels within a terrestrial food web encompassing land-applied biosolids, soil, earthworms (Lumbricus), deer mice (Peromyscus maniculatus), and eggs of European starlings (Sturnus vulgaris) and American kestrels (Falco sparverius) at an experimental site amended with biosolids for the previous 7 years. The samples from this site were compared to the same types of samples from a reference (biosolids-free) agricultural site. Inter-site comparisons showed that concentrations of both antimicrobials were higher on the experimental site in the soil, earthworms, mice (livers), and European starling eggs, but not American kestrel eggs, compared to the control site. Inter-species comparisons on the experimental site indicated significantly higher TCC concentrations in mice (TCC: 12.6-33.3 ng/g) and in starling eggs (TCC: 15.4-31.4 ng/g) than in kestrel eggs (TCC: 3.6 ng/g). Nesting success of kestrels only was significantly lower on the experimental site compared to the reference site due to nest abandonment. This study demonstrates that biosolids-derived TCC and TCS are present throughout the terrestrial food web, including secondary (e.g., starlings) and tertiary (i.e., kestrels) consumers, after repeated, long-term biosolids application.

Evolutionary toxicology: Meta-analysis of evolutionary events in response to chemical stressors

The regulatory decision-making process regarding chemical safety is most often informed by evidence based on ecotoxicity tests that consider growth, reproduction and survival as end-points, which can be quantitatively linked to short-term population outcomes. Changes in these end-points resulting from chemical exposure can cause alterations in micro-evolutionary forces (mutation, drift, selection and gene flow) that control the genetic composition of populations. With multi-generation exposures, anthropogenic contamination can lead to a population with an altered genetic composition, which may respond differently to future stressors. These evolutionary changes are rarely discussed in regulatory or risk assessment frameworks, but the growing body of literature that documents their existence suggests that these important population-level impacts should be considered. In this meta-analysis we have compared existing contamination levels of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) that have been documented to be associated with evolutionary changes in resident aquatic organisms to regulatory benchmarks for these contaminants. The original intent of this project was to perform a meta-analysis on evolutionary events associated with PCB and PAH contamination. However, this effort was hindered by a lack of consistency in congener selection for "total" PCB or PAH measurements. We expanded this manuscript to include a discussion of methods used to determine PCB and PAH total contamination in addition to comparing regulatory guidelines and contamination that has caused evolutionary effects. Micro-evolutionary responses often lead populations onto unique and unpredictable trajectories. Therefore, to better understand the risk of population-wide alterations occurring, we need to improve comparisons of chemical contamination between affected locations. In this manuscript we offer several possibilities to unify chemical comparisons for PCBs and PAHs that would improve comparability among evolutionary toxicology investigations, and with regulatory guidelines. In addition, we identify studies documenting evolutionary change in the presence of PCB and PAH contamination levels below applicable regulatory benchmarks.

Cross-resistance in Gulf killifish (Fundulus grandis) populations resistant to dioxin-like compounds

The Houston Ship Channel (HSC) in Houston, Texas is an aquatic environment with a long history of contamination, including polychlorinated dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. Populations of Gulf killifish (Fundulus grandis) from the HSC have adapted to resist developmental cardiac deformities caused by dioxin-like compounds (DLCs). Contaminants in the HSC have acted as a strong selective pressure on resident Gulf killifish populations. Rapid adaptation can lead to fitness costs, some as a direct result of the mechanisms involved in the adaptive process, whereas other adaptations may be more general. To explore potential fitness costs, we evaluated two Gulf killifish populations with documented resistance to DLC-induced cardiac teratogenesis (Patrick Bayou and Vince Bayou), and one previously characterized reference population (Gangs Bayou). We also characterized a previously unstudied population from Galveston Bay as an additional reference population (Smith Point). We tested the sensitivity of F1 larvae from these four populations to two classes of pesticides (pyrethroid (permethrin) and carbamate (carbaryl)) and two model pro-oxidants (tert-butyl hydroquinone (tBHQ) and tert-butyl hydroperoxide (tBOOH)). In addition, we explored their responses to hypoxia and measured resting metabolic rates (M.O2). Both adapted populations were cross-resistant to the toxicity of carbaryl and both pro-oxidants tested. There were no population differences in sensitivity to permethrin. On the other hand, one reference population (Gangs Bayou) was less sensitive to hypoxia, and maintained a lower M.O2 . However, there were no differences in hypoxia tolerance or resting metabolic rate between the second reference and the two adapted populations. This investigation emphasizes the importance of including multiple reference populations to clearly link fitness costs or cross-resistance to pollution adaptation, rather than to unrelated environmental or ecological differences. When compared to previous literature on adapted populations of Fundulus heteroclitus, we see a mixture of similarities and differences, suggesting that F. grandis adapted phenotypes likely involve multiple mechanisms, which may not be completely consistent among adapted populations.

Pressurized liquid extraction technique for the analysis of pesticides, PCBs, PBDEs, OPEs, PAHs, alkanes, hopanes, and steranes in atmospheric particulate matter

An analytical method has been developed for the pressurized liquid extraction (PLE) of a wide range of semi-volatile organic compounds (SVOCs) from atmospheric particulate matter. Approximately 130 SVOCs from eight compound classes were selected as molecular markers of (1) agricultural activity (30 current and historic-use pesticides), (2) industrial activity (18 PCBs), (3) consumer products and building materials (16 PBDEs, 11 OPEs), and (4) motor vehicle exhaust (22 PAHs, 16 alkanes, 9 hopanes, 8 steranes). Currently, there is no analytical method validated for the extraction of all eight compound classes in a single automated technique. The extraction efficiencies of varying solvents and solvent combinations at high temperatures and pressures were examined. Extracts were concentrated and analyzed by gas chromatography coupled with mass spectrometry. The optimized PLE method utilized methylene chloride:acetone (2:1 v/v) at 100 °C with three (5 min) static cycles, flush volume of 80%, and a 100 s N2 purge. Spike and recovery experiments (n=7) provided average percent recoveries for pesticides, PCBs, PBDEs, OPEs, PAHs, alkanes, hopanes, and steranes of 88.8±4.0%, 86.9±2.6%, 83.8±2.9%, 101±6%, 90.3±6.1%, 74.4±8.8%, 104±8%, and 86.5±8.6%, respectively. The developed method was applied to atmospheric particulate matter samples collected in the greater Houston, TX metropolitan area. Ambient concentrations of eight classes of compounds (92 SVOCs) were reported in pg m(-3).

Development and application of a novel method for high-throughput determination of PCDD/Fs and PCBs in sediments

A selective pressurized liquid extraction technique was developed for the simultaneous extraction of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) from contaminated sediments. The final method incorporated cleanup adsorbents (Florisil, alumina, and silica) into the extraction cell in a 1:1 ratio of matrix to individual adsorbent (w/w). Sulfur, a common interference found in sediments, was successfully removed by placing activated copper in the extraction bottle prior to extraction. No additional postextraction cleanup was required, and sample throughput was reduced to 2.5 h per sample. Target analytes were quantified using high-resolution gas chromatography/electron-capture negative ionization mass spectrometry and verified by high-resolution gas chromatography/high-resolution mass spectrometry. Though mean analyte recoveries (n = 3) of PCDD/Fs and dl-PCBs were 84 ± 5.8% and 70 ± 8.4%, respectively, mean surrogate recoveries for all PCDD/Fs using this novel method were greatly improved compared with US Environmental Protection Agency (USEPA) method 1613 (∼25-155%) and USEPA method 8290a (40-135%). After development, the method was used to examine surficial sediment samples from the San Jacinto River waste pits, a Superfund site in Houston, Texas, USA. In all samples, PCDD/Fs and dl-PCBs were detected, and the contaminant concentrations ranged over 5 orders of magnitude.

Evolved resistance to PCB- and PAH-induced cardiac teratogenesis, and reduced CYP1A activity in Gulf killifish (Fundulus grandis) populations from the Houston Ship Channel, Texas

The Houston Ship Channel (HSC), connecting Houston, Texas to Galveston Bay and ultimately the Gulf of Mexico, is heavily industrialized and includes several areas that have historically been identified as containing significant levels of mercury, dioxins, furans, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). Gulf killifish, Fundulus grandis, inhabit this entire estuarine system, including the most contaminated areas. F. grandis is the sister species of the well-established estuarine model organism Fundulus heteroclitus, for which heritable resistance to both PCB and PAH toxicity has been documented in several populations. F. grandis collected from two Superfund sites on the HSC and from a reference population were used to establish breeding colonies. F1 embryos from HSC populations were approximately 1000-fold more resistant to PCB126- and 2-5-fold more resistant to coal tar-induced cardiovascular teratogenesis, relative to embryos from the reference population. Reciprocal crosses between reference and contaminated populations exhibit an intermediate level of resistance, confirming that observed protection is genetic and biparentally inherited. Ethoxyresorufin-O-deethylase (EROD) data confirm a reduction in basal and induced cytochrome P4501A (CYP1A) activity in resistant populations of F. grandis. This result is consistent with responses previously described for resistant populations of F. heteroclitus, specifically a recalcitrant aryl hydrocarbon receptor (AHR) pathway. The decreased levels of cardiovascular teratogenesis, and decrease in CYP1A inducibility in response to PCB126 and a PAH mixture, suggest that HSC F. grandis populations have adapted to chronic contaminants exposures via a mechanism similar to that previously described for F. heteroclitus. To the best of our knowledge, this is the first documentation of evolved pollution resistance in F. grandis. Additionally, the mechanistic similarities between the population adaptation observed in this study and previous work in F. heteroclitus suggest that genetic variation predating the evolutionary divergence of these two species may best explain the apparent rapid parallel evolution of pollution resistance in genetically and geographically distinct species and populations.

Selective pressurized liquid extraction technique capable of analyzing dioxins, furans, and PCBs in clams and crab tissue

A selective pressurized liquid extraction technique (SPLE) was developed for the analysis of polychlorodibenzo-p-dioxins, polychlorodibenzofurans (PCDD/Fs) and dioxin-like polychlorobiphenyls (dl-PCBs) in clam and crab tissue. The SPLE incorporated multiple cleanup adsorbents (alumina, florisil, silica gel, celite, and carbopack) within the extraction cell. Tissue extracts were analyzed by high resolution gas chromatography coupled with electron capture negative ionization mass spectrometry. Mean recovery (n = 3) and percent relative standard deviation for PCDD/Fs and dl-PCBs in clam and crabs was 89 ± 2.3 and 85 ± 4.0, respectively. The SPLE method was applied to clams and crabs collected from the San Jacinto River Waste Pits, a Superfund site in Houston, TX. The dl-PCBs concentrations in clams and crabs ranged from 50 to 2,450 and 5 to 800 ng/g ww, respectively. Sample preparation time and solvents were reduced by 92 % and 65 %, respectively, as compared to USEPA method 1613.