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ARCHIVED - Environmental Screening Assessment Report on Perfluorooctane Sulfonate

Introduction

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires the Minister of the Environment and the Minister of Health to conduct screening assessments to determine 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, can suggest adding the substance to the Priority Substances List (PSL) for further assessment or can recommend the addition of the substance to the List of Toxic Substances in Schedule 1 and, where applicable, the implementation of virtual elimination.

An environmental 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. The approach taken in this environmental screening assessment is to examine various supporting information and develop conclusions based on a weight of evidence approach as required under Section 76.1 of CEPA 1999. The environmental 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 precursors, are also examined in this report.

An environmental screening assessment was undertaken on perfluorooctane sulfonate (PFOS), its salts and compounds that containing the perfluorooctylsulfonyl (C8F17SO2) or C8F17SO3 groups (the latter hereafter referred to as precursors) on the basis that some of these compounds were included in the Domestic Substances List (DSL) pilot list for screening based on their meeting the criteria for persistence and/or bioaccumulation and inherent toxicity, pursuant to Paragraph 73(1)(b) of CEPA 1999, and in response to a request to the Minister of the Environment to add these compounds to the PSL. The term PFOS may refer to any of its anionic, acid or salt forms. The perfluorooctylsulfonyl (C8F17SO2) or C8F17SO3 group is incorporated in a variety of compounds, and these compounds have the potential to transform or degrade back to PFOS in the environment. Due to similar use applications and the fact that PFOS is the persistent final degradation product of PFOS precursors, this environmental screening assessment addresses PFOS and its precursors together. Once PFOS is released to the environment, it is not known to undergo any further chemical, microbial or photolytic degradation and is considered persistent. Therefore, it is expected that the precursors contribute to the total amount of PFOS in the environment.

Data relevant to the environmental screening assessment of PFOS and its precursors were identified in original literature, review documents and industry research reports. A supporting document was prepared on selected perfluoroalkyl compounds, and degradation modelling (using CATABOL1 software) to predict PFOS precursors was performed. On-line literature database searches were conducted for select perfluoroalkyl compounds. As well, direct contacts were made with researchers, academics, industry and other government agencies to obtain relevant information on PFOS and its precursors.

Ongoing scans were conducted of the open literature, conference proceedings and the Internet for relevant information. Data obtained up to February 2004 were considered in this document. In addition, an industry survey on certain perfluoroalkyl and fluoroalkyl substances, their derivatives and polymers was conducted in 2000 through a Canada Gazette Notice issued under authority of Section 71 of CEPA 1999. This survey collected data on the Canadian manufacture, import and export of certain perfluorinated alkyl compounds (Environment Canada 2000). Existing toxicological studies were also submitted by industry under Section 70 of CEPA 1999.

The environmental screening assessment report and associated unpublished supporting working documentation were written by a team of Environment Canada evaluators at the Existing Substances Branch, Gatineau, Quebec. The information in this report has undergone external peer review by Canadian and international experts from government, industry and academia, including S. Beach (3M), W. De Coen (University of Antwerp, Belgium), P. de Voogt (University of Amsterdam), W. de Wolf (DuPont, Germany), S. Dimitrov (Prof. As Zlatarov University, Bourgas, Bulgaria), J. Giesy (Michigan State University), O. Hernandez (US Environmental Protection Agency), S. Mabury (University of Toronto), R. Medsker (private consultant), O. Mekenyan (Prof. As Zlatarov University, Bourgas, Bulgaria), D. Muir (Environment Canada, National Water Research Institute), R. Purdy (private consultant), E. Reiner (3M), M. Santoro (3M) and B. Scott (Environment Canada, National Water Research Institute).

The environmental and human health screening assessment reports were approved by the joint Environment Canada/Health Canada CEPA Management Committee. The supporting technical report is available upon request by e-mail from PSL.LSIP@ec.gc.ca. Information on environmental screening assessments under CEPA 1999 is available at http://www.ec.gc.ca/substances/ese. Information on the screening health assessment is available at http://www.hc-sc.gc.ca/ewh-semt/contaminants/existsub/screen-eval-prealable/index-eng.php.

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




Footnotes

1 CATABOL is a computer system for predicting biodegradability metabolic pathways and toxicity of stable biodegradation products. It is a product of the Laboratory of Mathematical Chemistry, University "Prof. As. Zlatarov," Bourgas, Bulgaria.

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