Chlorinated paraffins: chapter 1

1. Introduction

Chlorinated paraffins (CPs) are chlorinated derivatives of n-alkanes with carbon chain lengths from 10 to 38 carbon atoms, and with varying chlorine contents. Commercial products, of which there are over 2000 (Serrone et al. 1987), are complex mixtures of homologues and isomers. CPs with carbon chains containing 10-13 carbon atoms (C_10-13) are termed "short", those with 14 - 17 carbon atoms (C_14-17) are called "medium" and those having 18 or more carbon atoms (≥C₁₈) are called "long". This report addresses the short-chain chlorinated paraffins (SCCPs), the medium-chain chlorinated paraffins (MCCPs) and the long-chain chlorinated paraffins (LCCPs).

CP waxes appeared on the first Priority Substances List (PSL1) of the 1988 Canadian Environmental Protection Act (CEPA 1988), published in the Canada Gazette, Part I, on February 11, 1989. An assessment was performed to determine whether CPs should be considered "toxic" as defined under CEPA 1988 and was completed in 1993 (Government of Canada 1993a). As a result of this assessment, SCCPs were declared "toxic" under Paragraph 11(c) of CEPA 1988, because they were found to constitute a danger to human health. The conclusion of this assessment, published in the Canada Gazette, Part I, on January 22, 1994, also indicates that available data were considered insufficient to determine whether SCCPs, MCCPs or LCCPs could have immediate or long-term harmful effects on the environment as defined under paragraph 11(a) of CEPA 1988 and whether MCCPs or LCCPS could be considered "toxic" to human health as defined under paragraph 11(c) of CEPA 1988.

Subsequent to the completion of the PSL1 assessments, a revised CEPA, CEPA 1999, came into effect on March 31, 2000. Section 64 of CEPA 1999 has a definition of "toxic" that is similar to that in section 11 of CEPA 1988. CEPA 1999 places more emphasis on pollution prevention, and mandates the application of a weight of evidence approach and the precautionary principle when conducting and interpreting the results of risk assessments of existing substances. In addition, CEPA 1999 provides for special consideration of persistent and bioaccumulative substances. Substances that are shown to be both persistent and bioaccumulative, therefore, may be assessed using a more precautionary approach than is used for other substances.

In 1997, a Scientific Justification document recommending that SCCPs be candidate substances for management under Track 1 (virtual elimination) of the Toxic Substances Management Policy (TSMP) (Government of Canada 1995) was published (Environment Canada 1997). The overall conclusion of the document stated: "On the basis of the information reviewed, it is concluded that short chain chlorinated paraffins are predominantly anthropogenic, persistent, bioaccumulative, and CEPA-toxic. Short chain chlorinated paraffins satisfy all four criteria outlined in the Toxic Substances Management Policy to identify substances for management under Track 1. Therefore, short chain chlorinated paraffins are proposed for management under Track 1 of the Policy." During the public comment period on the Scientific Justification, the Chlorinated Paraffins Industry Association (CPIA) reviewed the information cited in the document proposing to list SCCPs as a Track 1 substance. They argued that the evidence did not constitute a scientifically credible basis to determine CEPA toxicity. Additionally, it was stated that the Scientific Justification document offered no persuasive evidence that SCCPs met the TSMP’s prescribed half-life criteria for persistence. In order to further examine the persistence of SCCPs and their potential to cause ecological harm, as well as to reassess MCCPs and LCCPs based on new information, scientists at the National Water Research Institute (NWRI) of Environment Canada and at the Freshwater Institute of the Department of Fisheries and Oceans (DFO) have generated new scientific information to address data gaps relevant to the assessment of impacts of CPs on the environment.

To set further context for the update of the CPs assessment, an industry survey on the Canadian manufacture, import and uses of CPs was conducted for the years 2000 and 2001 through a Canada Gazette Notice issued pursuant to section 71 of CEPA 1999 (Environment Canada 2003a). Recent literature was also reviewed for new exposure and toxicological data on CPs on human and non-human organisms in Canada and elsewhere.

This new information is considered in this assessment report. Data acquired prior to February 2001 and December 2000 were considered in the follow-up assessment of whether SCCPs and MCCPs/LCCPs, respectively, constitute or may constitute a danger in Canada to human life or health. Data obtained as of July 2007 were considered as part of the ecological follow-up assessment of SCCPs, MCCPs, and LCCPs.

This assessment report was prepared under the authority of Section 68 of CEPA 1999. It was written by the staff of the Existing Substances Division of Environment Canada and Health Canada, as well as the National Water Research Institute of Environment Canada. The content of this report has been subjected to external review by Canadian and international experts selected from government and academia, and also to a 60-day public comment period. However, the conclusions presented in this report are those of Environment Canada and Health Canada and do not necessarily reflect the opinions of the external reviewers.

This report represents a summary of more detailed information presented in a supporting document. For additional information the reader should consult this document. This assessment report and the associated environmental supporting document are available upon request by e-mail from ec.substances.ec@canada.ca. Information on assessments under CEPA 1999 is available on the Chemical Substances website.