Priority Substances List Assessment Report for Road Salts

1.0 Introduction

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires the federal Ministers of the Environment and of Health to prepare and publish a Priority Substances List (PSL) that identifies substances, including chemicals, groups of chemicals, effluents and wastes, that may be harmful to the environment or constitute a danger to human health. The Act also requires both Ministers to assess these substances and determine whether they are "toxic" or capable of becoming "toxic" as defined in Section 64 of the Act, which states:

...a substance is toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that

1. have or may have an immediate or long-term harmful effect on the environment or its biological diversity;
2. constitute or may constitute a danger to the environment on which life depends; or
3. constitute or may constitute a danger in Canada to human life or health.

Substances that are assessed as "toxic" as defined in Section 64 may be placed on the List of Toxic Substances in Schedule I of the Act and considered for possible risk management measures, such as regulations, guidelines, pollution prevention plans or codes of practice to control any aspect of their life cycle, from the research and development stage through manufacture, use, storage, transport and ultimate disposal.

Based on initial screening of readily accessible information, the rationale for assessing road salts provided by the Ministers' Expert Advisory Panel on the Second Priority Substances List (Ministers' Expert Advisory Panel, 1995) was as follows:

The Panel recognized the benefits associated with the use of road salts. However, these substances have negative effects on the environment. Large volumes are released through road salting, particularly in Ontario, Quebec and the Atlantic provinces. There is evidence of adverse local environmental effects to groundwater and to plant and animal life following exposure. Algae and benthic fauna have been shown to be particularly sensitive to changes in chloride ion concentrations, resulting in a reduction of fish populations. The Panel recognizes that there has been considerable progress in upgrading storage facilities. However, given the widespread exposure to these substances, and their release in large volumes into the Canadian environment, the Panel believes that an assessment is needed to determine their ecological effects.

The basis for inclusion of road salts by the Ministers' Expert Advisory Panel on the Second Priority Substances List was limited to environmental effects and did not identify concerns with respect to human health. Humans are exposed to road salts principally through the contamination of roadside well waters, where chloride and sodium levels can be increased and taste adversely affected. These elements are not considered toxic; in fact, the Canadian drinking water guidelines for chloride and sodium are based on taste, which is affected at levels well below those that might be of concern for toxicity (Health Canada, 1996). Other substances contained in road salts, including ferrocyanide compounds and certain metals, are present only at trace levels.

With respect to the potential for health effects of sodium chloride road salts, an extensive literature search failed to identify any studies that were adequate to serve as the basis for a health risk assessment. In one study dermal exposure to concentrated solutions of road salt caused dermal irritation, but no sensitization (Cushman et al., 1991). There is a single correlational study in which a statistical association between road salt use and mortality from a number of types of cancer in the United States was identified (Foster, 1993). However, in this study, road salt use would have varied in parallel with a number of other factors; for example, larger amounts of salt are used in urban centres, where there is also more exposure to air pollution. There would also have been differences among states in smoking patterns, diet and a host of other factors. The design of this exploratory study does not permit adjustment for these other factors, many of which are more plausible causes of cancer than is road salt.

In view of the focus of this assessment on environmental effects defined by the Ministers' Expert Advisory Panel and the extremely limited and inadequate data available related to the potential impacts of road salts on human health, this assessment solely addresses effects on the environment (i.e., the determination of whether road salts are "toxic" under Paragraphs 64(a) and 64(b) of CEPA 1999).

Descriptions of the approaches to assessment of the effects of Priority Substances on the environment are available in a published companion document. The document entitled "Environmental Assessments of Priority Substances under the Canadian Environmental Protection Act. Guidance Manual Version 1.0 -March 1997" (Environment Canada, 1997a) provides guidance for conducting environmental assessments of Priority Substances in Canada. This document may be purchased from:

• Environmental Protection Publications
  Environmental Technology Advancement Directorate
  Environment Canada
  Ottawa, Ontario
  K1A 0H3

It is also available on the Existing Substances Branch web site at www.ec.gc.ca/cceb1/eng/psap.htm under the heading "Technical Guidance Manual." It should be noted that the approach outlined therein has evolved to reflect changes in the Canadian Environmental Protection Act and to incorporate recent developments in risk assessment methodology, which will be addressed in future releases of the guidance manual for the assessment of effects of Priority Substances on the environment.

The search strategies employed in the identification of data relevant to the assessment of potential effects on the environment (prior to May 2001) are presented in Appendix A. Review articles were consulted where appropriate. However, all original studies that form the basis for determining whether road salts are "toxic" under CEPA 1999 have been critically evaluated.

Preparation of the environmental components of the assessment was led by B. Elliott under the direction of R. Chénier. Extensive supporting documentation (Appendix B) related to the environmental assessment of road salts was prepared and reviewed by the Environmental Resource Group established in June 1997 by Environment Canada to support the environmental assessment:

• P. Arp, University of New Brunswick
• M. Barre, Environment Canada (until December 1999)
• Y. Bourassa, Environment Canada (since December 1999)
• L. Brownlee, Environment Canada (until April 2000)
• B. Butler, University of Waterloo
• N. Cain, Cain Vegetation Inc.
• R. Chénier, Environment Canada
• C. Delisle, École Polytechnique de Montréal
• M. Eggleton, Environment Canada (until February 2000)
• B. Elliott, Environment Canada
• M. Evans, Environment Canada
• K. Hansen, Ontario Ministry of the Environment
• J. Haskill, Environment Canada
• K. Howard, University of Toronto (until January 2000)
• A. Letts, Morton International Inc.
• B. Mander, Environment Canada
• T. Mayer, Environment Canada
• P. Mineau, Environment Canada (since April 2000)
• D. Morin, Environment Canada
• M. Perchanok, Ontario Ministry of Transportation
• R. Smith, Transportation Association of Canada
• W. Snodgrass, Snodgrass Consultants
• K. Taylor, Environment Canada
• M. Weese, Ontario Ministry of Transportation (until January 1999)
  
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Environmental Resource Group members also reviewed the Assessment Report prepared by Environment Canada. Conclusions and interpretations in this report are those of Environment Canada and do not necessarily represent those of all members of the Environmental Resource Group.

Environmental supporting documentation was also reviewed by:

• K. Adare, Environment Canada
• J. Addison, Royal Roads University
• J. Van Barneveld, British Columbia Ministry of Environment, Lands and Parks
• Y. Bédard, Ministère des Transports du Québec
• D. Belluck, Minnesota Department of Transport
• Y. Blouin, Ville de Cap-de-la-Madeleine
• R. Brecher, Global Tox
• C. Chong, University of Guelph
• A. Decréon, Ministère des Transports du Québec
• R. Delisle, Ministère des Transports du Québec
• G. Duval, Ministère des Transports du Québec
• A. El-Shaarawi, Environment Canada
• A. Fraser, Environment Canada
• M. Frénette, Ville de Montréal
• D. Gutzman, Environment Canada
• G. Haines, New Brunswick Department of Transportation
• R. Hodgins, Ecoplans Limited
• M. Kent, British Columbia Ministry of Transportation and Highways
• C. MacQuarrie, New Brunswick Department of Transportation
• B. Mason, City of Toronto
• L. McCarty, L.S. McCarty Consulting
• G. McRae, Ontario Ministry of Transportation
• T. Pollock, Environment Canada
• M. Roberts, University of New Brunswick
• D. Rushton, Nova Scotia Department of Transportation and Public Works
• K. Solomon, University of Guelph
• R. Stemberger, Dartmouth College, New Hampshire
• T. Young, Clarkson University, New York

The Assessment Report was reviewed and approved by the Environment Canada/Health Canada CEPA Management Committee.

The Assessment Report for Road Salts was released in August 2000 for a 60-day public comment period. Following consideration of comments received, the Assessment Report was revised. A summary of the public comments and responses from Environment Canada and Health Canada is available by contacting the Existing Substances Branch (see address below) or on the Internet at:

 www.ec.gc.ca/cceb1/ese/eng/psap.htm

Copies of this Assessment Report are available upon request from:

• Inquiry Centre
  Environment Canada
  Main Floor, Place Vincent Massey
  351 St. Joseph Blvd.
  Hull, Quebec
  K1A 0H3

or on the Internet at:

 www.ec.gc.ca/cceb1/ese/eng/psap.htm

Unpublished supporting documentation, which presents additional information, is available upon request from:

• Existing Substances Branch
  Environment Canada
  14th Floor, Place Vincent Massey
  351 St. Joseph Blvd.
  Hull, Quebec
  K1A 0H3
  
  e-mail: PSL.LSIP@ec.gc.ca