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3. Sources and environmental fate of halomethoxybenzenes

Author

Zhan, Faqiang, primary, Shunthirasingham, Chubashini, additional, Li, Yuening, additional, Oh, Jenny, additional, Lei, Ying Duan, additional, Ben Chaaben, Amina, additional, Dalpé Castilloux, Abigaëlle, additional, Lu, Zhe, additional, Lee, Kelsey, additional, Gobas, Frank A. P. C., additional, Alexandrou, Nick, additional, Hung, Hayley, additional, and Wania, Frank, additional

Published
2023
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4. The atmospheric fate of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH): spatial patterns, seasonal variability, and deposition to Canadian coastal regions

Author

Oh, Jenny, primary, Shunthirasingham, Chubashini, additional, Lei, Ying Duan, additional, Zhan, Faqiang, additional, Li, Yuening, additional, Dalpé Castilloux, Abigaëlle, additional, Ben Chaaben, Amina, additional, Lu, Zhe, additional, Lee, Kelsey, additional, Gobas, Frank A. P. C., additional, Eckhardt, Sabine, additional, Alexandrou, Nick, additional, Hung, Hayley, additional, and Wania, Frank, additional

Published
2023
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5. Bioaccumulation of Linear Siloxanes in Fish.

Author

Cantu, Mark A. and Gobas, Frank A. P. C.

Subjects
*BIOACCUMULATION, *DISSOLVED organic matter, *ENVIRONMENTAL chemistry, *BIOMAGNIFICATION, *ENVIRONMENTAL toxicology
Abstract

The bioaccumulation behavior, including the uptake, internal distribution, depuration, and biotransformation rates, of three widely used linear methyl‐siloxanes was investigated in rainbow trout. Dietary uptake efficiencies of octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), and dodecamethylpentasiloxane (L5) were 15% (3.3% standard error [SE]), 8.6% (1.4% SE), and 15% (1.8% SE), respectively, and for L3 and L4 were well below those of nonmetabolizable reference chemicals with similar octanol–water partition coefficients, suggesting significant intestinal biotransformation of L3 and L4. Somatic biotransformation rate constants were 0.024 (0.003 SE) day–1 for L3 and 0.0045 (0.0053 SE) day–1 for L4 and could not be determined for L5. Lipid‐normalized biomagnification factors for L3, L4, and L5 were 0.24 (0.02 SE), 0.24 (0.01 SE), and 0.62 (0.05 SE) kg‐lipid kg‐lipid–1, respectively. Bioconcentration factors standardized to a 5% lipid content fish for water in Canadian oligotrophic lakes with a dissolved organic carbon content of 7.1 mg L–1 were 2787 (354 SE) for L3, 2689 (312 SE) for L4, and 1705 (418 SE) L kg‐wet weight–1, respectively, and 3085 (392 SE) for L3, 4227 (490 SE) for L4, and 3831 (938 SE) L kg‐wet weight–1 in water with a dissolved organic carbon content of 2.0 mg L–1. A comparison of 238 bioaccumulation profiles for 166 different chemicals shows that the bioaccumulation profiles for L3, L4, and L5 are vastly different from those of other very hydrophobic compounds found in the environment. Environ Toxicol Chem 2024;43:42–51. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Methods for assessing the bioaccumulation of hydrocarbons and related substances in terrestrial organisms: A critical review.

Author

Gobas, Frank A. P. C., Lee, Yung‐Shan, Fremlin, Katharine M., Stelmachuk, Stephanie C., and Redman, Aaron D.

Subjects
BIOACCUMULATION, ENVIRONMENTAL chemistry, STRUCTURE-activity relationships, BIOMAGNIFICATION, ENVIRONMENTAL toxicology, BIOINDICATORS
Abstract

This study investigates and reviews methods for the assessment of the terrestrial bioaccumulation potential of hydrocarbons and related organic substances. The study concludes that the unitless biomagnification factor (BMF) and/or the trophic magnification factor (TMF) are appropriate, practical, and thermodynamically meaningful metrics for identifying bioaccumulative substances in terrestrial food chains. The study shows that various methods, including physical–chemical properties like the KOA and KOW, in vitro biotransformation assays, quantitative structure–activity relationships, in vivo pharmacokinetic and dietary bioaccumulation tests, and field‐based trophic magnification studies, can inform on whether a substance has the potential to biomagnify in a terrestrial food chain as defined by a unitless BMF exceeding 1. The study further illustrates how these methods can be arranged in a four‐tier evaluation scheme for the purpose of screening assessments that aim to minimize effort and costs and expediate bioaccumulation assessment of the vast numbers of organic substances in commerce, identifies knowledge gaps, and provides recommendations for further research to improve bioaccumulation assessment. Integr Environ Assess Manag 2023;19:1433–1456. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: •A four‐tier terrestrial bioaccumulation (TB) screening assessment scheme for hydrocarbons and related organic substances is presented.•The TB screening scheme makes use of various sources of information including physical–chemical properties (KOA and KOW), in vitro biotransformation assays, quantitative structure–activity relationships, in vivo tests, and field‐based trophic magnification studies. [ABSTRACT FROM AUTHOR]

Published
2023
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7. The atmospheric fate of 1,2-Dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH): Spatial patterns, seasonal variability, and deposition to Canadian coastal regions

Author

Oh, Jenny, Shunthirasingham, Chubashini, Lei, Ying Duan, Zhan, Faqiang, Li, Yuening, Dalpé Castilloux, Abigaëlle, Ben Chaaben, Amina, Lu, Zhe, Lee, Kelsey, Gobas, Frank A. P. C., Eckhardt, Sabine, Alexandrou, Nick, Hung, Hayley, and Wania, Frank

Abstract

Brominated flame retardants (BFRs) that are gradually phased out are being replaced by emerging BFRs. Here, we report the concentration of the α- and β-isomers of 1,2-Dibromo-4-(1,2-dibromoethyl) cyclo–hexane (TBECH) in over 300 air, water, and precipitation samples collected between 2019 and 2022 using active air and deposition sampling as well as networks of passive air and water samplers. The sampling region includes Canada's most populated cities and areas along the St. Lawrence River and Estuary, Quebec, as well as around the Salish Sea, British Columbia. TBECH was detected in over 60 % of air samples at levels comparable to those of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). Concentrations of TBECH and BDE-47 were typically higher in urban areas, with stronger correlations with population density during warmer deployments. Uniform α/β-TBECH ratios across space, time and environmental media indicate highly similar atmospheric fate of the two isomers. Although TBECH air concentrations were strongly related to temperature in urban Toronto and a remote site on the East coast, the lack of such dependence at a remote site on the West coast can be explained by the small seasonal temperature range and summertime air mass transport from the Pacific Ocean. Despite there being no evidence that TBECH has been produced, or imported for use, in Canada, it is now one of the most abundant gaseous BFRs in the Canadian atmosphere. The recorded spatial and temporal variability of TBECH suggest that its emissions are not constrained to specific locations but are generally tied to the presence of humans. The most likely explanation for its environmental occurrence in Canada is the release from imported consumer products containing TBECH. Chiral analysis suggests that despite its urban origin, at least some fraction of TBECH has experienced enantioselective processing, i.e., has volatilized from reservoirs where it has undergone microbial transformations. Microbial processes in urban soils and in marine waters may have divergent enantioselectivity.

Published
2023

16. A Chemical Activity Approach to Exposure and Risk Assessment of Chemicals

Author

Gobas, Frank A. P. C., Mayer, Philipp, Parkerton, Thomas F., Burgess, Robert M, Van de Meent, Dik, van de Meent, Dik, and Gouin, Todd

Subjects
010504 meteorology & atmospheric sciences, Health, Toxicology and Mutagenesis, Environmental fate, Environmental media, Guidelines as Topic, 010501 environmental sciences, Environmental stewardship, 01 natural sciences, Risk Assessment, Article, Exposure, Hazard/ risk assessment, Mixture, Environmental Chemistry, Environmental quality, 0105 earth and related environmental sciences, Risk assessment, Probability, Chemical activity, Environmental exposure, Environmental Exposure, Hazard, Bioaccumulation, Adaptive management, Risk analysis (engineering), Solubility, Environmental science, Environmental Pollutants, Hazard/risk assessment
Abstract

To support the goals articulated in the vision for exposure and risk assessment in the twenty-first century, we highlight the application of a thermodynamic chemical activity approach for the exposure and risk assessment of chemicals in the environment. The present article describes the chemical activity approach, its strengths and limitations, and provides examples of how this concept may be applied to the management of single chemicals and chemical mixtures. The examples demonstrate that the chemical activity approach provides a useful framework for 1) compiling and evaluating exposure and toxicity information obtained from many different sources, 2) expressing the toxicity of single and multiple chemicals, 3) conducting hazard and risk assessments of single and multiple chemicals, 4) identifying environmental exposure pathways, and 5) reducing error and characterizing uncertainty in risk assessment. The article further illustrates that the chemical activity approach can support an adaptive management strategy for environmental stewardship of chemicals where "safe" chemical activities are established based on toxicological studies and presented as guidelines for environmental quality in various environmental media that can be monitored by passive sampling and other techniques. Environ Toxicol Chem 2018;37:1235-1251. © 2018 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.

Published
2018

17. Bioaccumulation of persistent organic pollutants in lichen-caribou-wolf food chains of Canada's central and western Arctic

Author

Kelly, Barry C. and Gobas, Frank A. P. C.

Subjects
Northern Canada -- Environmental aspects, Pollution control industry -- Research, Lichens -- Research, Caribou -- Research, Wolves -- Research, Environmental issues, Science and technology
Abstract

Samples from lichen, willow leaves, caribou, and wolves are taken from Canada's Arctic region to determine the bioaccumulation of first generation POPs in the Arctic ecosystem. The authors claim that current limits on toxic emissions are insufficient because of instinces of biomagnification of POPs in the food chain.

Published
2001

20. Development and field validation of a multimedia exposure assessment model for waste load allocation in aquatic ecosystems: application to 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in the Fraser River watershed

Author

Gobas, Frank A. P. C., Pasternak, John P., Lien, Kent, and Duncan, Ramona

Subjects
Environmental indexes -- Evaluation, Environmental monitoring -- Equipment and supplies, Water quality -- Measurement, Environmental issues, Science and technology
Abstract

EcoFate is found to be a viable tool in water quality management as it helps determine what combination of emission levels will result in ambient concentrations that meet water quality standards. EcoFate is a time-dependent multimedia mass balance simulation model for the environmental distribution and food-chain accumulation of organic contaminants in aquatic ecosystems.

Published
1998

22. Development and verification of a benthic/pelagic food web bioaccumulation model for PCB cogeners in Western Lake Erie

Author

Morrison, Heather A., Gobas, Frank A. P. C., Lazar, Rodica, Whittle, D. Michael, and Haffner, G. Douglas

Subjects
Lake Erie -- Research, Food chains (Ecology) -- Models, Bioaccumulation -- Models, Polychlorinated biphenyls -- Research, Environmental issues, Science and technology
Abstract

A benthic/pelagic food web bioaccumulation model was developed using data accumulated from Western Lake Erie. The model was designed to derive chemical concentration estimates from filter-feeding and detritovorous benthic invertebrates, zooplankton, phytoplankton, and fish. Data on PCB concentrations in the lake was used to test the model.

Published
1997

27. Development and Evaluation of Aquatic and Terrestrial Food Web Bioaccumulation Models for Per- and Polyfluoroalkyl Substances

Author

Kelly, Barry C., Sun, Jennifer M., McDougall, Mandy R. R., Sunderland, Elsie M., and Gobas, Frank A. P. C.

Abstract

There is a need for reliable models to predict the food web bioaccumulation and assess ecological and human health risks of per- and polyfluoroalkyl substances (PFAS). This present study presents (i) the development of novel mechanistic aquatic and terrestrial food web bioaccumulation models for PFAS and (ii) an evaluation of model performance using available laboratory and field data. Model predictions of laboratory-measured bioconcentration factors and field-based bioaccumulation factors of PFAS in fish were in good agreement with observed data as measured by the mean model bias (MB), representing systematic over- or under-estimation and the standard deviation of the MB, representing general uncertainty. The models provide a mechanistic framework for evaluating the combined effect of simultaneously occurring uptake and elimination processes and indicate food web-specific magnification of PFAS, with the highest degree of biomagnification occurring in food webs composed of air-breathing wildlife. Albumin-water, structural protein–water, membrane-water distribution coefficients, and renal clearance rate are among the most important model parameters. With further development and testing, these models may be useful for future PFAS screening and risk assessment initiatives and advance bioaccumulation studies of PFAS by providing a mechanistic framework for PFAS bioaccumulation.

Published
2024
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35. Characterisation of polymer-coated glass (POGs) as passive air samplers for persistent organic pollutants.

Author

Harner, Tom, Farrar, Nick, Shoeib, Mahiba, Jones, Kevin C., Gobas, Frank A. P. C., Harner, Tom, Farrar, Nick, Shoeib, Mahiba, Jones, Kevin C., and Gobas, Frank A. P. C.

Abstract

The use of thin-film polymer-coated glass surfaces or POGs as passive air samplers was investigated during an uptake experiment in an indoor environment with high levels of gas-phase polychlorinated biphenyls (PCBs). POGs consisted of a micron thick layer of ethylene vinyl acetate (EVA) coated onto glass cylinders. The uptake was initially linear with time and governed by the air-side mass transfer coefficient and surface area of the sampler. This was followed by a curvilinear region and finally a constant phase when equilibrium was established between air and EVA. The high surface area-to-volume ratio of the POGs allowed rapid equilibrium with gas-phase PCBs; equilibration times were on the order of hours for the low molecular weight congeners. The equilibrium concentration was dependent on the EVA-air partition coefficient, KEVA-A, which was shown to be very well correlated to the octanol−air partition coefficient, KOA. When POGs of varying thickness were equilibrated with air, the amount of PCB accumulated increased with increasing thickness of the EVA, indicating that uptake was by absorption into the entire polymer matrix. A wind field of 4 m s-1 resulted in an increased uptake rate by a factor of approximately six compared to uptake in relatively still air. This wind speed effect was diminished, however, when POGs were housed in deployment chambers consisting of inverted stainless steel bowls. Relationships based on the air-side mass transfer coefficient and KEVA-A were developed for PCBs that describe the entire uptake profile and allow air concentrations to be determined from the amount of chemical accumulated in the POG. It is believed that these relationships are also valid when POGs are used to detect other classes of persistent organic pollutants.

Published
2003

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