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Environmental Toxicology Research Group
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Research Philosophy

Our research philosophy relies on the exploration of the mechanisms of chemical uptake, elimination, transformation and bioaccumulation in laboratory experiments and field studies. Mechanistic insights are formalized in mathematical models, which are tested in field studies. The models are then applied in a regulatory context to conduct exposure and hazard assessments such as the bioaccumulation categorization (for Environment Canada), and the development of water quality criteria and pesticide exposure models in the US[10-14]. Previous work was centered on 3 studies.

Food-Web Distribution & Bioaccumulation
Our recent bioaccumulation field and modeling studies of organic chemicals in piscivorous, terrestrial, marine mammalian and human food-webs in Northern Canada, published in[9,15,16,32,34] and most recently in Science[1], demonstrate that chemicals with a relatively low octanol-water partition coefficient Kow (<105), which generally do not biomagnify in fish, can biomagnify in air-breathing organisms (including mammals, birds and humans) if they have octanol-air partition coefficients (KOA) >105 and are not rapidly metabolized. The study concludes that the current regulatory model which uses fish bioconcentration test data and/or Kow to identify bioaccumulative substances should be revisited as this model is not able to identify many bioaccumulative chemicals in non-piscivorous (including human) food-chains. This is a significant finding because two-thirds of all commercial chemicals have a KOA > 105, and half of those chemicals have a log Kow between 2 and 5 and are miscategorized by current regulations[34]. We have proposed new criteria[1,32,34] and have been involved as a member of the steering committee in the organization of an international workshop of the Society for Environmental Toxicology and Chemistry (SETAC, January 27-31, 2008) to improve bioaccumulation assessments by international regulatory agencies[43].

Bioavailability
To test the hypothesis that the exposure of wildlife to chemicals is better characterized by the chemical fugacity than by the total chemical concentration (the current approach) we have (i) developed methods which use thin films of ethylene vinyl acetate (EVA) to measure fugacities of chemicals in biological tissues[4], in air[24], soil[12,15] and sediments[7,11,16] and (ii) tested the relationship between sediment fugacities (as measured by our method) and chemical concentrations in two invertebrates species in laboratory and field studies[7,11]. Laboratory studies with spiked natural sediments reveal highly reproducible thin-film extractions for chemicals with log KOW between 4.5 and 8.5, with 95% equilibration times between 1-600 h. Studies with field-collected sediments illustrate that method detection limits are sufficiently low for field application at contaminated sites. Bioaccumulation studies in invertebrates show excellent correlations between thin-film and animal tissue concentrations. We conclude that thin-film extraction provides an ecologically relevant, fugacity-based measure of chemical bioavailability that can be expected to improve sediment quality assessments. We are currently working with Golder Associates Ltd. to apply the method to hydrocarbon contaminated sediments.

Food-Web Bioaccumulation Model Development & Application
To better assess the exposure of organic chemicals to wildlife, we have developed and tested a new aquatic food-web bioaccumulation model for contaminants[5] (i.e. a revised version of our 1993 model). A modified version of this model[33] has been adopted by Environment Canada to categorize commercial chemicals in Canada[51]. We also published a bioconcentration data base and a review of bioaccumulation assessment used for the categorization[18]. We also developed and tested a novel bioenergetic bioaccumulation model for consumer organisms[2,44]. The model, which conserves chemical mass as well as energy, expands bioaccumulation assessment to all consumer organisms. We also developed and tested a new bioaccumulation model for organic chemicals in terrestrial food-webs[13,32]. In addition, we contributed modeling studies to support chemical risk assessments for migrating salmon populations[27], fish farming[28] and aboriginal fisheries[38] in BC and in support of a remediation plan for San Francisco Bay[42,50,53]. We also contributed studies to improve model parameterization[14], model description[25] and model dissemination[46]. Our most recent work on the development of the pesticide risk assessment model AGRO in collaboration with the Canadian Environmental Modeling Center at Trent University is currently being evaluated for use in pesticide registration in the US[56].

References:
1. D.C. Muir , S. Backus, A.E. Derocher, R. Dietz, T.J. Evans, G.W. Gabrielsen, J. Nagy, R.J. Norstrom, C. Sonne, I. Stirling, M.K. Taylor, R.J. Letcher. Environ Sci Technol 40, 449 (2006)
2. H. Wolkers, B. Van Bavel, A.E. Derocher, O. Wiig, K.M. Kovacs, C. Lydersen, G. Lindstrom. Environ Sci Technol 38, 1667 (2004)
3. K. Noren, D. Meironyte. Chemosphere 40, 1111 (2000)
4. G. T. Tomy, W. Budakowski, T. Halldorson, P. A. Helm, G. A. Stern, K. Friesen, K. Pepper, S. A. Tittlemier, A. T. Fisk, Environ. Sci. Technol. 38, 6475 (2004)
5. K. Kannan, J. Koistinen, K. Beckmen, T. Evans, J. F. Gorzelany, K. J. Hansen, P. D. Jones, E. Helle, M. Nyman, J. P. Giesy, Environ. Sci. Technol. 35, 1593 (2001)
6. J. P. Giesy, K. Kannan, Environ. Sci. Technol. 35, 1339 (2001)
7. F. Wania. Environ. Sci. Technol., 41, 4529 (2007)
8. J.C. Deon, S.A. Mabury. Environ. Sci. Technol., 41, 4799 ( 2007).
9. S.A. Tittlemier, K. Pepper, C. Seymour, J. Moisey, R. Bronson, X. Cao, R.W. Dabeka. J. Agric. Food Chem., 55, 3203 (2007)
10. USEPA.1995. Great lakes Water Quality Initiative Technical Support Document for the Procedure to Determine Bioaccumulation factors. Office of Water, Washington, DC. EPA/820/B-95/005.
11. USEPA. 2000. Methodology for deriving Water Quality Criteria for the Protection of Human Health. EPA 822-B-00-004. Office of Water, US Environmental Protection Agency.
12. USEPA. 2003. Methodology for deriving Ambient Water Quality Criteria for the Protection of Human Health. Technical Support Document Volume 2: Development of National Bioaccumulation factors. Office of Science and Technology, Office of Water, Washington, DC. EPA-R-03-030.US Environmental Protection Agency, Washington DC, December 2003.
14. USEPA. 2008. Methods for Assessing Ecological Risks of Pesticides with Persistent, Bioaccumulative and Toxic Characteristics. Office of Prevenetion, Pesticides and Toxic Substances.US Environmental Protection Agency, Washington DC, October 2008. Under Review.
15. B.C. Kelly and F.A.P.C. Gobas. Environ. Sci. Technol. 35(2): 325-334 (2001)
16. C. E. Mackintosh, J. Maldonado, J. Hongwu, N. Hoover, A. Chong, M. G. Ikonomou and F. A. P. C. Gobas. Environ. Sci. Technol. 38(7) : 2011  2020 (2004).
17. A.V. Weisbrod, L.P. Burkhard, J. Arnot, O. Mekenyan, P.H. Howard, Russom, C. R. Boethling, Y. Sakuratani, T. Traas, T. Bridges, C. Lutz, M. Bonnell, K. Woodburn, T. Parkerton, Environ. Health Perspect. 115, 255 (2006).
18. J.A. Arnot, D. Mackay, M. Bonnell Environ. Toxicol. Chem. 27(2) In press (2008).
19. X. Han, D.L. Nabb, R.T. Mingoia, C.H. Yang. Environ. Sci. Technol. 41, 3269 (2007)
20. J.W. Nichols, I.R. Schultz, P.N. Fitzsimmons. Aquatic Toxicology, 78, 74 (2006)
21. C.J. Kennedy, 1995. Xenobiotics: designing an in vitro system to study enzymes and metabolism. In: Hochachka, P.W., Mommsen, T.P. (Eds.), Biochemistry and Molecular Biology of Fishes, Vol. 3.: Analytical Techniques. Elsevier Science, Amsterdam. pp. 417-430.
22. F.A.P.C. Gobas, J.W.B. Wilcockson, R.W. Russell, G.D. Haffner. Environ. Sci. Technol. 33, 133 (1999).
23. T. Iwatsubo, N. Hirota , T. Ooie, H. Suzuki, N. Shimada. Pharmacology & Therapeutics, 73, 147 (1997)
24. S. Haddad, M. Bliveau, R.Tardif, K. Krishnan. Toxicological Sciences 63, 125 (2001)

More references:
IMPORTANT RESEARCH CONTRIBUTIONS (student names are in bold)
1. Kelly, B.C., M.G. Ikonomou, J.D. Blair, A.E. Morin and F.A.P.C. Gobas. 2007. Food Web Specific Biomagnification of Persistent Organic Pollutants. Science 307: 236-239. This contribution building on previous work demonstrates that current Kow based methods for identifying chemical substances with a bioaccumulation potential in international (UNEP 1999) & national legislation (CEPA 1999) miscategorizes chemicals with a bioaccumulation potential in terrestrial food-chains. The paper proposes and support simple Koa based rules that can be used for bioaccumulation assessment to identify substances that biomagnify in terrestrial but not in aquatic food-chains. We expect these findings to have consequences for the regulation of many thousands of commercial chemicals.
2. DeBruyn, A.M.H. and F.A.P.C. Gobas. 2005. A Bioenergetic Biomagnification Model for the Animal Kingdom. Environ. Sci. Technol. 40: 1581-1587. This paper reports a novel bioaccumulation modeling approach applying closed matter and energy mass balances to determine biomagnification factors of pollutants in wildlife.
3. Gobas, F.A.P.C., J.W.B. Wilcockson, R.W. Russell and G.D. Haffner. 1999. Mechanism of Biomagnification in Fish under Laboratory and Field Conditions. Environ. Sci. Technol. 33: 133-141. These laboratory experiments and field studies provide insights into how persistent organic pollutants (POPs) are magnified in the gastro-intestinal tract of fish as a result of food digestion & absorption. It supports key aspects of our mathematical models to estimate the degree of biomagnification of POPs in food-chains].
4. Wilcockson, J.W.B. and F.A.P.C. Gobas. 2001. Thin Film Solid-Phase Extraction to Measure Fugacities of Poorly-Volatile Organic Chemicals in Biological Samples. Environ. Sci. Technol. 35: 1425-1431. This method, which measure the fugacities of organic chemicals, presents a simple method to better measure the bioavailability of contaminants in various environmental media, including air and possibly sediment and soil. To conduct meaningful risk assessments of contaminated soils and sediments, a method of this kind is required but does currently not exist.
5. Arnot, J.A. and F.A. P. C. Gobas. 2004. A Food Web Bioaccumulation Model for Organic Chemicals in Aquatic Ecosystems. Environ. Toxicol. Chem. 23, 2343-2355. This model is widely used for bioaccumulation assessment and adopted in legislative initiatives in the US (Great Lakes Water Quality Initiative ((EPA-822-R-94-002) & pesticide registration) and in Canada for the categorization of chemicals on the Domestic Substances List.
6. Alava, J.J., P.S. Ross, M.G. Ikonomou, D. Costa, S. Salazar, and F.A.P.C. Gobas. 2008. Polybrominated diphenyl ether (PBDE) flame retardants in Galapagos sea lions (Zalophus wollebaeki). Environ. Chem. Toxicol. In press.
7. Meloche, L.M., S.V. Otton, M.G. Ikonomou, A.M.H. DeBruyn and F.A.P.C. Gobas. 2008. Assessing sediment quality using thin-film solid phase extraction. Environ. Chem. Toxicol. In press.
8. Kelly, B.C., M.G. Ikonomou, J.D. Blair and Gobas, F.A.P.C. 2008. Behaviour of Hydroxylated and Methoxylated PBDEs in a Canadian Arctic Food-Web. Environ. Sci. Technol. 42: 7069-7077.
9. Kelly, B.C., Michael G. Ikonomou, Joel D. Blair, Frank A.P.C. Gobas. 2008. Bioaccumulation behaviour of polybrominated diphenyl ethers (PBDEs) in a Canadian Arctic marine food web. Science of the Total Environment 401, 60-72.
10. Otton, S.V., S. Sura, J. Blair, M.G. Ikonomou, F.A.P.C. Gobas. 2008. Biodegradation of Mono-Alkyl Phthalate Esters in Natural Sediments. Chemosphere 71: 2011-2016.
11. Golding, C.J.; Gobas, F.A.P.C.; Birch, G.F. 2008. A Fugacity Approach for Assessing the Bioaccumulation of Hydrophobic Organic Compounds from Estuarine Sediment. Environ. Toxicol. Chem. 1047-1054.
12. Vasiluk L., L.J. Pinto, W.S. Tsang, F.A.P.C. Gobas, C. E. Eickhoff and M.M. Moore. 2008. The uptake and metabolism of benzo[a]pyrene from a sample food substrate in an in vitro model of digestion. Food and Chemical Toxicology. 46(2): 610-618.
13. Armitage, J.M. and F.A.P.C Gobas, 2007. A Terrestrial Bioaccumulation Model for POPs. Environ. Sci. Technol. 41 (11), 4019-4025.
14. DeBruyn, A.M.H. and F.A.P.C. Gobas. 2007. The Sorptive Capacity of Animal Protein. Environ. Toxicol. Chem. 26 (9): 1803-1808.
15. Vasiluk, L., L.J. Pinto, Z.A. Walji, W.S. Tsang, F.A.P.C. Gobas, C. Eickhoff, and M.M. Moore. 2007. Benzo[a]pyrene bioavailability from pristine soil and contaminated sediment assessed using two in vitro models. Environ. Toxicol. Chem. 26: 387-393.
16. Golding, C.J.; Gobas, F.A.P.C.; Birch, G.F. (2007) Characterisation of PAH bioavailability in estuarine sediments using Thin Film Extraction. Environ. Toxicol. Chem. 26(5):829-836
17. Cheng, W.W.L. and F.A.P.C. Gobas. 2007. Assessment of Human Health Risks of Consumption of Cadmium Contaminated Cultured Oysters. Human. Ecol. Risk Assess. 13: 370-382.
18. Arnot, J.A. and F.A.P.C. Gobas. 2006. A review of bioconcentration factor (BCF) and bioaccumulation factor (BAF) assessments for organic chemicals in aquatic organisms. Environmental Reviews 14: 257-297.
19. Macintosh, C.E., J.A. Maldonado, M.G. Ikonomou and F.A.P.C. Gobas. 2006. Sorption of Phthalate Esters and PCBs in a Marine Ecosystem. Environ. Sci. Technol. 2006; 40(11); 3481-3488.
20. Gobas, F.A.P.C., M.M. Moore, J.L.M. Hermens and Jon A. Arnot. 2006. Bioaccumulation Reality Check. SETAC Globe 7(4), 40-41.
21. Sunderland, E.M.H.A., F.A.P.C. Gobas, B.A. Branfireun, A. Heyes,. 2006. Environmental Controls on the Speciation and Distribution of Mercury in Coastal Sediments. Marine Chemistry 102: 111-123.
22. Minhas, J.K.,L. Vasiluk, L.J. Pinto, F.A.P.C. Gobas and M.M. Moore. 2006, Mobilization of chrysene from soil in a model digestive system. Environ. Toxicol. Chem. 25(7): 1729-1737.
23. Kelly, B.C., M.G. Ikonomou and F.A.P.C. Gobas. 2005. Biomagnification Potential of Polybrominated Diphenylethers in a Canadian Arctic Marine Food Web. Organohalogen Compounds. Pp. 1240-1242.
24. Harner, T., Mahiba Shoeib, Melissa Kozma, Frank A.P.C. Gobas, Shao Meng Li. 2005. Organochlorine pesticides in urban, rural and high altitude samples in the Fraser Valley, B. C.: Evidence for trans-Pacific transport. Environ. Sci. Technol. 39(3): 724-731.
25. Kelly, B.C., M.S. McLachlan and F.A.P.C. Gobas. 2004. Intestinal Absorption and Biomagnification of Organic Contaminants in Fish, Wildlife and Humans. Environ. Toxicol. Chem. 23, 2324-2336.
26. Macintosh, C.E., J. Maldonado, J. Hongwu, N. Hoover, A. Chong, M.G. Ikonomou and F.A.P.C. Gobas. 2004. Distribution of Phthalate Esters in a Marine Aquatic Food-Web. Environ. Sci. Technol. 38(7): 2011 - 2020.
27. DeBruyn, A.M.H. and F.A.P.C. Gobas, M.G. Ikonomou. 2004. Magnification and Toxicity of PCBs, PCDDs and PCDFs in Upriver Migrating Pacific Salmon. Environ. Sci. Technol. 38: 6217-6224.
28. DeBruyn, A.M.H. and F.A.P.C. Gobas. 2004. Modelling the Diagenetic Fate of POPs in Organically Enriched Sediment, Ecological Modeling. 179, 405-416.
29. Arnot, J.A. and F.A.P.C. Gobas. 2004. A Food Web Bioaccumulation Model for Organic Chemicals in Aquatic Ecosystems. Environ. Toxicol. Chem. 23, 2343-2355.
30. Gobas, F.A.P.C. and D.C.G. Muir. 2004. A World Model, a Model World. Environ. Toxicol. Chem. 23, 2279-2280.
31. Sunderland, E.M., B.A. Branfireun, A.K. Bayer, A. Heyes, R.E. Cranston, M.B. Parsons and F.A.P.C. Gobas. 2004. Speciation of Mercury in Well-Mixed Estuarine Sediments. Marine Chemistry 90, 91-105.
32. Kelly, B.C. and F.A.P.C. Gobas. 2003. An Arctic Terrestrial Food-Chain Bioaccumulation Model for Persistent Organic Pollutants. Environ. Sci. Technol. 37: 2966-2974.
33. Arnot, J.A., Gobas, F.A.P.C. 2003. A generic QSAR for Assessing the Bioaccumulation Potential of Organic Chemicals in Aquatic Food-webs. QSAR Comb. Sci. 22: 337-345.
34. Gobas, F.A.P.C., B.C. Kelly, J.A. Arnot. 2003. Quantitative Structure Activity Relationships for Predicting the Bioaccumulation of POPs in Terrestrial Food-Webs. QSAR Comb. Sci. 22: 346-351.
35. Lin, Z., M.G. Ikonomou, C.E. Mackintosh, J. Hongwu and F.A.P.C. Gobas. 2003. Determination of Phthalate Ester Congeners and Mixtures in Sediments and Biota of an Urbanized Coastal Marine Inlet. Environ. Sci. Technol. 2003; 37(10) : 21002108.
36. Eickhoff, C.V., S.X. He, F.A.P.C. Gobas and F.C.P. Law. (2003). Determination Of Polycyclic Aromatic Hydrocarbons In Dungeness Crabs (Cancer magister) Near An Aluminium Smelter In Kitimat Arm, BC. Environmental Toxicology and Chemistry 22: 50-58.
37. Eickhoff, C.V., F.A.P.C. Gobas and F.C.P. Law. (2003). Screening Pyrene Metabolites in the Haemolymph of Dungeness Crabs (Cancer magister) Using Synchronous Fluorescence Spectrometry: Method Development and Application. Environmental Toxicology and Chemistry 22: 59-66.
38. Wiseman, C.L.S. and F.A.P.C. Gobas. 2002. Balancing Risks in the Management of Contaminated Aboriginal Fisheries. Int. J. Environ. Health. Res. 12 (4), 331-342.
39. Harner, T., N. Farrar, M. Shoeib, K. Jones and F.A.P.C. Gobas. 2003. Characterisation of Polymer-Coated Glass (POGs) as Passive Air Samplers for Persistent Organic Pollutants. Environ. Sci. Technol. 37: 2486-2493.
40. Gobas, F.A.P.C. and L.G. MacLean. 2003. Sediment-water distribution of organic contaminants in aquatic ecosystems: the role of organic carbon mineralization. Environ. Sci. Technol. 37(4): 735-741.
41. Li, P.C.H., E. J. Swanson, F.A.P.C.Gobas. 2002. Diazinon and its Degradation Products in Agricultural Water Courses in British Columbia, Canada. Bulletin of Environ. Contam. Toxicol. 69:59-65.
42. Gobas, F.A.P.C. and J.A. Arnot. 2008. San Francisco Bay PCB Food Web Bioaccumulation Model. Environ. Chem. Toxicol. Submitted.
43. Gobas, F.A.P.C., W.de Wolf, E. Verbruggen, K. Plotzke, L. Burkhard. 2008 Revisiting Bioaccumulation Criteria for POPs and PBT Assessments. Integrated Environmental Assessment and Management. . Submitted.
44. Fan, Y., A.M.H. DeBruyn, B.C. Kelly and F.A.P.C. Gobas. 2008. A Bioenergetic Bioaccumulation Model to Assess Trophic Magnification factors. Environ. Sci. Technol. Submitted
45. R.S. Boethling, R. Chenier, C.E. Cowan-Ellsberry, W. de Wolf, P. Dohmen, S.J. Eisenreich, B. Escher, F.A.P.C. Gobas, K.C. Jones, G.M. Klecka, D. Mackay, M. McLachlan, D.C.G. Muir, J. Nichols, M. Scheringer, J.R. Snape, K.R. Solomon, D.L. Swackhamer, J.V. Tarazona, D. van Wijk, A.V. Weisbrod, K.B. Woodburn (in alphabetical order). 2008. Science Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs: Summary of a SETAC Pellston Workshop. Integrated Environmental Assessment and Management. . Submitted.
46. Gobas, F.A.P.C. 2008. Food-Web Bioaccumulation Models. In Encyclopedia of Ecology, Volume 2: Environmental Toxicology (Jorgensen, S.E. and Fath B.D. (editor-in-Chief.) Elsevier, Oxford. Pp. 1643-1652.
47. Kelly, B.C., M.G. Ikonomou and F.A.P.C. Gobas. 2005. Biomagnification Potential of Polybrominated Diphenylethers in a Canadian Arctic Marine Food Web. Proceedings of the Dioxin 2005 Conference, Toronto, Ontario. Pp. 1243-1246.
48. Gobas, Frank A.P.C., Cheryl E. Mackintosh, Glenys Webster, Michael Ikonomou, Thomas F. Parkerton, Kenneth Robillard. 2003. Handbook of Environmental Chemistry: Phthalates (O. Hutzinger ed.) pp. 201-225.
49. Gobas, F.A.P.C. 2001. Assessing Bioaccumulation Factors of Persistent Organic Pollutants in Aquatic Food-Chains, In: Persistent Organic Pollutants: Environmental Behaviour and Pathways of Human Exposure, ed S. Harrad, Pubd. Kluwer Academic, pp 145-165.
50. Gobas, F.A.P.C., J.A. Arnot. 2005. San Francisco Bay PCB Food-Web Bioaccumulation Model. Regional Monitoring Program. San Francisco Bay, Pp. 163.
51. Gobas, F.A.P.C., J.A. Arnot. 2003. Categorization of organic substances on the Domestic Substances List for Bioaccumulation Potential, Report to Environment Canada, Ottawa, Pp. 110.
52. Blust, R., D. Calamari, P.Dalgaard, A. DePaola, J.M. Fremy, F.A.P.C. Gobas, B. Jansson, C. Karman, T. Vermeire, D. Weston, W. Wosniok, R. Cormier, P. Hernandez. (alphabetical order). 2003. Environmental Exposure Models for Application in Seafood Risk Analysis. Report to IMO/FAO/UNESCO-IOC/WMO/WHO/IAEA/UN/UNEP GESAMP XXXII/8. Pp. 45.
53. Gobas, F.A.P.C. and J.B. Wilcockson. 2002. San Francisco Bay PCB Food-Web Model:Remedial Management Plan Technical Report. San Francisco Estuary Management Institute, pp. 46.
54. Gobas, F.A.P.C. and J.B. Wilcockson. 2000. Thin Film Solid-Phase Extraction to Measure Fugacities of Poorly Volatile Organic Chemicals. US Provisional Patent #60/240089, Filed: Oct 16, 2000. This patent includes a thin-film solid phase extraction device to measure fugacities of organic chemicals in various environmental media.
55. Gobas, F.A.P.C. 2002. Reaction to Environmental Risk Limits for Polychlorinated Biphenyls in the Netherlands: Derivation with Probabilistic Food Chain Modeling In Health Council of the Netherlands. Recommended exposure limits for polychlorinated biphenyls in soils and sediments, for the protection of ecosystems. The assessment of a derivation method devised by the National Institute of Public Health. ISBN 90-5549-460-7. Pp. 70-72.
56. Gobas, F.A.P.C. 2008. EcoRisk Assessment of Pesticides. 4th Pan Pacific Conference on Pesticide Science. 4th Pan Pacific Conference on Pesticide Science, American Chemical Society, June 1-5, 2008, Waikiki Beach, Honolulu, Hawaii.

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