Impact of Polybrominated Diphenyl Ethers on Canadian Environment and Health of Canadians

Principle Investigator:
Mehran Alaee
Aquatic Ecosystem Conservation Branch
National Water Research Institute
867 Lakeshore Road, PO Box 5050
Burlington, ON L7R 4A6

mehran.alaee@cciw.ca

Contributing Partner(s):
Michel Lebeuf, Department of Fisheries and Oceans
David Sergeant, Department of Fisheries and Oceans
Nigel Bunce, University of Guelph
Michael Ikonomou, Department of Fisheries and Oceans
John Jake Ryan, Health Canada
Bryan Wakeford, Environment Canada
Chris Metcalfe, Trent University

Project Length:
3 Years

Funding:
1999-2000: $120,000
2000-2001: $179,000
2001-2002: $155,000

Why Project Was Undertaken: Global use of flame retardants has more than tripled in the past 20 years. Environmentally persistent polybrominated diphenyl ethers (PBDEs) are the second largest group of these chemicals. PBDEs have been found in sediments, shellfish, fish, sea birds and mammals in Europe and Japan, and in human tissues in the US. High levels of PBDEs may affect the nervous system and thyroid hormone levels in animals. Little is known about PBDEs in Canada.

How Project Was Conducted: Three main objectives of TSRI project #237 were to determine: I) the status of PBDEs in the Canadian aquatic environment; ii) the status PBDE exposure in Canadians; and iii) the potential health effects of high exposures to PBDEs. PBDEs in Canadian breast milk and some foods, fish, fish-eating birds, and other organisms of the Great Lakes, St. Lawrence and west coast of Canada were measured by QA/QC analytical chemistry methods developed at Canadian research centres. The physical properties of some PBDEs and their levels in air and sediments of remote lakes and in the Arctic were also studied. International workshops were held.

What Was Found and Conclusions: Levels of PBDEs in sediments, animals and humans are on the rise in Canada. During the past 20 years levels of PBDEs in the Canadian environment have increased, accordingly, 100Xs to 1000Xs in lake trout of the Great Lakes, 10Xs to 100Xs in water birds, 10Xs in arctic mammals, 100Xs in breast milk, and > 1000Xs in belugas of the St. Lawrence. PBDE levels are greatest in top predatory fish and fish-eating wildlife in aquatic food webs. The relative Canadian daily dietary intake of 3 major groups of POPs was PCBs >PBDEs> dioxins. Levels of PBDEs in Canadian breast milk samples ranged from 19 ppb in the Maritimes to 2.6 ppb in Ontario. A commercial mixture of PBDEs affected tail reduction in exposed tadpoles suggesting that thyroid activity was disrupted. Tadpoles fed excessive levels of BDE-71or dieldrin in food showed the same response. Other BDEs had no effect in fish and tadpoles. Research is ongoing. PBDEs bind less strongly than dioxin to the cell site involved in the breakdown of organic chemicals. PBDEs have low volatility. BDE-209 in sediment of Lake Ontario were high. BDE-209 was not found in arctic lakes.

Executive Summary

This project addressed the key area of determining and linking the ecosystem and human health effects of polybrominated diphenyl ethers, an emerging group of POPs identified in TSRI Priority Section 3. Polybrominated diphenyl ethers (PBDEs) are extensively used as flame-retardant compounds. The annual global market demand for PBDEs has grown from 20,000 tonnes in 1984 to 40,000 tonnes in 1992 and 67,000 tonnes in 1999. This project addressed both toxicity and exposure, the two key elements required in risk assessment.

At Trent University the effect PBDEs and other BFRs on early life stages of fish, thyroid agonist and antagonism toxicity in fish, and alteration to retinoid homestatis in fish were studied under the supervision of Dr. Chris Metcalfe. Initial studies at Trent University indicated that the in vivo testing with early life stages of fish and amphibians did not respond to BDE-47 and -99 tested. Inhibition of tail resorption was observed in tadpoles exposed to a commercial PBDE mixture. Exposure to DE-71 at a concentration of 1000 g per gram of food significantly (p<0.05) retarded the rate of tail regression. Differences in tail lengths were noted within approximately two to three weeks of initiation of exposure and persisted until the end of the experiment. Similar effects were observed in tadpoles exposed to dieldrin at the same concentration.

Dixon-like toxicity of PBDEs was evaluated by Dr. Nigel Bunce and his research team at the University of Guelph. Results from this study indicated that PBDEs are at best weak Ah receptor agonists, which bind to the Ah receptor with no more than M dissociation constants, 2-5 orders of magnitude less strongly than TCDD. Like other halogenated aromatic compounds (HACs) that bind the Ah receptor weakly, PBDEs can act as antagonists to strong agonists such as TCDD, and PCBs 77 and 126.

Linkage of PBDEs to human health effects were established through the study of the sources and pathways of PBDEs to humans; by determination of the spatial levels and temporal trends in human tissue (breast milk); and exposure to PBDEs via commercial fatty foods, such as, meats and dairy products by Dr. Jake Ryan and his colleagues at Health Canada. Concentrations of PBDEs in human breast milk from across Canada ranged between 19.08 ng/g for samples collected from the Maritimes and 2.57 ng/g for samples collected in Ontario. Levels of PBDEs in breast milk rose from a mean of 0.2 ng/g for samples collected across Canada in 1982 to a mean of 42.5 ng/g (25.4 ng/g median) lipid weight for samples collected in the Vancouver area in 2001-2. Concentrations of PBDEs in a number of food basket items were also determined in this study. PBDE concentrations ranged between 0.04 ng/g for pasta and 1.2 ng/g for wieners; these values resulted in an estimated daily dietary intake of 44 ng, which was higher than PCDD/Fs (2.4 ng), and lower than PCBs (285 ng).

PBDE levels in wildlife including temporal trends in herring gull eggs from Great Lakes, blue heron eggs from Vancouver, British Colombia and in two seabird species from the Arctic were analyzed at CWS under the supervision of Bryan Wakeford. Temporal trends for PBDEs among all of the species indicated an increase in the concentration of PBDEs over the past two decades; for example the concentration of PBDEs in great blue heron eggs increased from 1.3 ng/g wet weight in 1983 to 194 ng/g wet weight in 2000; between 1975 and 1998 the concentration of PBDEs increased from 0.9 ng/g wet weight to 2.9 ng/g wet weight in thick billed murre; during the same period concentration of PBDEs in northern Fulmer increased from 0.2 ng/g wet weight to 1.7 ng/g wet weight in northern fulmer.

Levels of PBDEs in biota and sediments from the St. Lawrence Estuary were determined by Dr. Michel Lebeuf and his colleagues at IML. Concentrations of PBDEs were lowest in shrimps and worms with levels ranged between 0.2 and 0.7 ng/g-wet weight. Both pelagic and demersal fish show similar levels of PBDEs, ranged between 13 ng/g-wet weight in muscle of Greenland halibut and 275 ng/g-wet weight in liver of Atlantic tomcod. As expected the highest PBDE levels, up to 700 ng/g wet weight, were found in harbor seals and beluga whales. The temporal trend of PBDEs in beluga whales doubled every c.a. 2 years in both male and female belugas in the St. Lawrence estuary during the past ten years. The increase in concentration of PBDEs in beluga whales is supported by sediment core data, which provided further evidence that these compounds have recently increased in the environment of eastern Canada.

At GLLFAS spatial distribution of PBDEs in lake trout from the Great Lakes and temporal trends in lake trout in Lake Ontario along with biomagnification of PBDEs in Lake Ontario food web were accomplished under the supervision of Dave Sergeant and Mike Whittle. PBDE levels range between 22 ng/g-wet weight for Lake Erie and 84 ng/g-wet weight for Lake Ontario. The levels of PBDEs in lake trout from Lake Ontario increased from 0.12 ng/g-wet weight in 1978 to 148 ng/g-wet weight in 1998. Biomagnification factors for PBDEs in Lake Ontario food web ranged between 0.6 for transfer of BDE-99 from diporeia to sculpin, and 5.7 for transfer of BDE-100 from plankton to mysid.

At IOS, u nder th e direction of Dr. Michael Ikonomou, several biota samples were collected from sites near urban/industrial areas along the west coast of Canada. The PBDE levels found were much higher than in the Ringed seals from remote Holman Island. In addition to Ringed seal, Dungeness crab hepatopancreas (199-478 ppb), English sole liver (22-339 ppb), and Harbor porpoise blubber (652-2269 ppb) were analyzed. In order to establish temporal trends, PBDE were measured in Ringed seal blubber from Holman Island, NWT collected in 1981, 1991, 1996 and 2000. The levels of PBDEs increased from 0.6 ng/g in 1981 to 6 ng/g in 2000, a 10-fold increase over 19 years.

Work on physical properties and abiotic media was conducted at NWRI under the supervision of Drs. Mehran Alaee and Derek Muir. The vapor pressures (PL) of 22 BDE congeners were determined as a function of temperature with a gas chromatographic retention time technique. PL at 25°C ranged between 0.1 Pa for mono-BDE and 10^-5 Pa for hexa-BDE. Concentration of PBDEs in archived air samples from the Arctic and the Great Lakes were determined, along with sediment cores from Lake Ontario and several remote lakes. Elevated concentrations of BDE-209 were observed in Lake Ontario. The concentrations of BDE-209 in sediment cores decreased with the increase in the altitude, BDE-209 was not detectable in sediment cores from arctic lakes.

In summary PBDEs are ubiquitous anthropogenic contaminants, which have been detected in numerous environmental matrices across Canada. Temporal trend studies indicated that the concentrations of these compounds are on the rise in the Canadian environment. Toxicity data indicate potential for thyroid hormone effects. The combination of rising concentrations of PBDEs with evidence for potential thyroid hormone effects is cause for concern.

Publications

Publications in scientific journals

Accepted/Published articles

Alaee M., Wenning R.J. (Guest Editors). 2002. Special issue: Brominated flame retardants in the environment. Chemosphere. 46 (5).

Alaee, M., Sergeant, D.B., Ikonomou, M.G., Luross, J.M. 2001. A gas chromatography/ high hesolution mass spectrometry method for determination of polybrominated diphenyl ethers in fish. Chemosphere. 44: 1489-1495.

Alaee M., Wenning, R.J. 2002. The significance of brominated flame retardants in the environment: current understanding, issues and challenges. Chemosphere. 46: 579-582.

Alaee, M., Backus, S., Cannon, C. 2001.Potential interference of PBDEs in the determination of PCBS and other organochlorine contaminants using electron capture detection. Jour. Sep. Sci. 24: 465-469.

Chen, G., Konstantinov, A.D., Chittim, B.G., Heikkila, E., Bols, N.C., Bunce, N.J. 2001. Synthesis of polybrominated diphenyl ethers (PBDEs) and their capacity to induce CYP1A by the Ah receptor mediated pathway. Environ. Sci. Tech. 35: 3749-3756.

Ikonomou, M.G., Rayne, S., Fischer, M., Fernandez, M.P., Cretney, W. 2002. Occurrence and congeners profiles of polybrominated diphenyl ethers (PBDEs) in environmental samples from Western Canada. Chemosphere. 46: 649-643.

Ikonomou, M.G., Rayne, S., Addison, R.F. 2002. Exponential increases of the brominated flame retardants, polybrominated diphenyl ethers, in the Canadian Arctic from 1981 to 2000. Environ. Sci. Tech. 36: 1886-1892.

Luross, J.M., Alaee, M., Sergeant, D.B., Cannon, C.M., Whittle, D.M., Solomon, K.R., Muir D.C.G. 2002. Spatial distribution of polybrominated diphenyl ethers and polybrominated biphenyls in lake trout from the Laurentian Great Lakes. Chemosphere. 46: 665-672.

Palm, A., Cousins, I.T., Mackay, D., Tysklind, M., Metcalfe, C., Alaee, M. 2002.
Assessing the environmental fate of chemicals of emerging concern: A case study of the polybrominated diphenyl ethers. Enviro. Pollut. 117: 195-213

Wong, A., Lei, Y.D., Alaee, M., Wania, F. 2001. Vapor pressures of the polybrominated diphenyl ethers. Jour. Chem. Eng. Data. 46: 239-242.

Submitted articles

Alaee M. 2002. The requisite and criteria for monitoring of polybrominated diphenyl ethers in Canadian environment.

Luross, J.M., Alaee, M., Cannon, C.M., Sergeant, D.B., Whittle, D.M., Solomon, K.R., Muir D.C.G. 2002. Temporal distribution of polybrominated diphenyl ethers and polybrominated biphenyls in lake trout from Lake Ontario, 1978-1998.

Norstrom R.J., Simon, M., Moisey, J., Wakeford, B., Weseloh, D.V.C. 2002. Geographical distribution (2000) and temporal trends (1981 to 2000) of brominated diphenyl ethers in Great Lakes herring gull eggs.