The figure depicts the chemical structure for polybrominated diphenyl ethers which are a class of chemical compounds in which 1 to 10 bromine atoms are attached to the diphenyl ether molecule and have the chemical formula, C12H(9 to 0)Br(1 to 10)O. In total, 209 possible PBDE congeners may be formed.

where x + y = 1 to 10

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires the Minister of the Environment and the Minister of Health to conduct screening assessments of substances that meet the categorization criteria set out in the Act and Regulations to determine, in an expeditious manner, whether substances present or may present a risk to the environment or to human health. Based on the results of a screening assessment, the Ministers can propose taking no further action with respect to the substance, adding the substance to the Priority Substances List (PSL) for further assessment, or recommending that the substance be added to the List of Toxic Substances in Schedule 1 and, where applicable, the implementation of virtual elimination.

A screening assessment involves an analysis of a substance using conservative assumptions to determine whether the substance is “toxic” or capable of becoming “toxic” as defined in CEPA 1999. This environmental screening assessment examines various supporting information and develops conclusions based on a weight of evidence approach as required under Section 76.1 of CEPA 1999. The screening assessment does not present an exhaustive review of all available data; rather, it presents the most critical studies and lines of evidence supporting the conclusions. One line of evidence includes consideration of risk quotients to identify potential for ecological effects. However, other concerns that affect current or potential risk, such as persistence, bioaccumulation, chemical transformation and trends in ambient concentrations, are also examined in this report.

Seven polybrominated diphenyl ethers (PBDEs) were identified in a pilot project list of 123 substances for screening assessment under CEPA 1999, on the basis of their potential persistence and/or bioaccumulation in the environment and inherent toxicity to environmental organisms.

Data relevant to the environmental screening assessment of PBDEs were identified in original literature, review documents, and commercial and government databases and indices. In addition to retrieving the references from a literature database search, direct contacts were made with researchers, academics, industry and other government agencies to obtain relevant information on PBDEs. Ongoing scans were conducted of the open literature, conference proceedings and the Internet for relevant PBDE information. Data obtained as of October 2003 were considered in this document. In addition, an industry survey on PBDEs was conducted for the year 2000 through a Canada Gazette Notice issued pursuant to Section 71 of CEPA 1999. This survey collected data on the Canadian manufacture, import, uses and releases of PBDEs (Environment Canada). Toxicological studies were also submitted by industry under Section 70 of CEPA 1999.

This environmental screening assessment report and associated unpublished supporting working documentation was written by a team of Environment Canada evaluators at the Environmental Protection Branch, Pacific and Yukon Region, Vancouver, B.C., with the assistance of evaluators and management at the Existing Substances Branch, Gatineau, Quebec. The substance matter in this report has been subjected to external review by Canadian and international experts selected from government and academia, including M. Alaee (Environment Canada, National Water Research Institute), L. Birnbaum (U.S. Environmental Protection Agency), C. de Wit (Stockholm University), S. Dungey (UK Environment Agency), R. Hale (College of William and Mary, Virginia), R. Law (UK Centre for Environmental, Fisheries and Aquaculture Science), F. Luckey (U.S. Environmental Protection Agency), J. Maguire (Environment Canada, National Water Research Institute), R. Norstrom (Environment Canada, National Wildlife Research Centre), D. Stewart (Environment Canada, Ontario Region).

The environmental and human health screening assessment reports were approved by the joint Environment Canada/Health Canada CEPA Management Committee. The supporting working documentation for the environmental assessment is available upon request by e-mail from Information on environmental screening assessments under CEPA 1999 is available at The supporting working documentation for the human health assessment is available upon request by e-mail from Additional background information on health screening assessments conducted under this program is available at

The critical information and considerations upon which the assessment is based are summarized below.

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