Priority Substances List Assessment Report for Inorganic Chloramines

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.

Canada to human life or health. Substances that are assessed as "toxic" as defined in Section 64 may be placed on 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 the assessment of chloramines provided by the Ministers' Expert Advisory Panel on the Second Priority Substances List (PSL2) (Ministers' Expert Advisory Panel, 1995) was as follows:

Chloramines - predominantly monochloramine - are found in drinking water, sewers, waste discharges from sewage treatment plants and industrial water supplies treated with chloramines. Other sources include breaks and leaks in watermains, fire fighting runoff and storm-water runoff from domestic water supplies treated with these substances. Chloramines are used as a disinfectant in secondary treatment of drinking water. Chloramines can persist in water from hours to days. They are highly toxic to fish and other aquatic organisms. An assessment is necessary to determine the extent of environmental exposure in Canada and the associated risks.

Based on the conclusion of the Ministers' Expert Advisory Panel that "An assessment is necessary to determine the extent of environmental exposure in Canada and the associated risks," the principal focus of this report is the determination of whether inorganic chloramines are "toxic" under Paragraph 64(a) of CEPA 1999. However, determination of "toxic" to environmental organisms and considerations for subsequent risk management of one of the principal sources of chloramines in the environment - i.e., the disinfection of drinking water supplies - must necessarily be balanced against the beneficial impacts of chloramine use on human health. Monochloramine is used by many water treatment plants (WTPs) in Canada as a secondary disinfectant to maintain residual disinfection activity in potable water distribution systems. In addition, chloramines may be generated as by-products of drinking water chlorination. Chloramination is considered to offer several advantages, such as increased residual activity in the distribution system, reduction of the formation of trihalomethanes (THMs) and other by-products associated with chlorine use, possible control of bacterial biofilm regrowth in the distribution system and, in some circumstances, reduction of taste and odour problems associated with chlorination of drinking water supplies.

Monochloramine is the predominant form of chloramine in chloraminated drinking water, with concentrations far exceeding those of either dichloramine or trichloramine. In 1995, a drinking water guideline of 3.0 mg/L for total chloramines was developed, based on the toxicity of monochloramine (Health Canada, 1995). Based on a review of recent scientific literature, including 13-week repeated-dose toxicity studies conducted by Health Canada in which rats were administered dichloramine and trichloramine in drinking water (Nakai et al., 2000), significant new information that would impact on the outcome of this previous assessment was not identified (Health Canada, 2000).

In view of the focus of this assessment defined by the Ministers' Expert Advisory Panel and the beneficial impact of the use of chloramine in the disinfection of drinking water supplies, the remainder of this assessment addresses effects on the environment. The only exception is reference in Section 3.4 to the need to ensure adequate health protection while minimizing potential for harm to environmental organisms in considering options for control in relation to drinking water sources.

Although the chemical group chloramines includes both inorganic and organic congeners, the risk assessment was conducted on inorganic chloramines only. This reflects the main intent of the conclusion of the Ministers' Expert Advisory Panel. The rationale for their addition to PSL2 concerned chloramines that are used as disinfectants. The predominant congener used for disinfection is monochloramine, which is an inorganic chloramine species. Throughout this assessment, the term chloramine will refer to inorganic chloramines (monochloramine, dichloramine or trichloramine), unless otherwise specified. The current state of scientific knowledge relevant to organic chloramines has been researched and documented in a supporting document (see El-Farra et al., 2000). However, where appropriate, other chlorine residual species (both free chlorine and organic chloramine species) are considered, since chloramines are rarely found in an isolated pure form. Further details regarding chloramine chemistry are located in Section 2.1 of this report and in supporting documents no. 1 (Pasternak and Powell, 2000) and no. 2 (El-Farra et al., 2000).

A description of the approaches to assessment of the effects of Priority Substances on the environment is 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), has been published to provide 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 Commercial Chemicals Evaluation Branch website atwww.ec.gc.ca/cceb1/ese/eng/esehome.htm under the heading "Guidance Manual." It should be noted that the approach outlined therein has evolved to incorporate recent developments in risk assessment methodology, which will be addressed in future releases of the guidance manual for environmental assessments of Priority Substances.

The literature and data search strategies employed in the identification of data relevant to assessment of entry, environmental fate and exposure and potential effects on the environment (prior to January 1999) are presented in Appendix A. Although much of the research on chloramine has been conducted outside Canada, available data on sources, use patterns and fate of chloramines in the Canadian environment have been emphasized. Review articles were consulted where appropriate. However, all original studies that form the basis for determining whether chloramine is "toxic" under CEPA 1999 have been critically evaluated by the staff of Environment Canada and members of an Environmental Resource Group established by Environment Canada to assist in the writing and review of the environmental assessment for chloramines and in the collection of exposure data.

The lead for the PSL assessment of inorganic chloramines was B. Kelso, Environment Canada. This Assessment Report was prepared by J.P. Pasternak, Environment Canada. The supporting documents for the environmental assessment of inorganic chloramines (El-Farra et al., 2000; Farrell and Wan, 2000; McCullum et al., 2000; Pasternak, 2000; Pasternak and Powell, 2000; Moore et al., 2000) were produced by:

• S.A. Andrews, University of Waterloo
• C. Buday, Environment Canada
• W. Cheng, Environment Canada
• S.A. El-Farra, University of Waterloo
• A.P. Farrell, Simon Fraser University
• B. Kelso, Environment Canada
• C. Kennedy, Simon Fraser University
• W.B. Kindzierski, University of Alberta
• M.A. Lemke, Environment Canada
• K. McCullum, University of Alberta
• J.S. Meyer, University of Wyoming
• D. Moore, Cadmus Group Inc.
• J.P. Pasternak, Environment Canada
• L. Powell, Environment Canada
• S.J. Stanley, University of Alberta
• S. Teed, Cadmus Group Inc.
• G. VanAggelen, Environment Canada
• A. Wagenaar, Environmental Consultant
• M.T. Wan, Environment Canada
• R.G. Watts, Environment Canada

Several technical workgroups were formed to undertake the assessment. The workgroup leads included:

• S.A. Andrews, University of Waterloo (Chemistry Workgroup)
• J.P. Pasternak, Environment Canada (Pathways Workgroup)
• A.P. Farrell, Simon Fraser University/ M.T. Wan, Environment Canada (Toxicity Workgroup)
• D. Moore, Cadmus Group Inc./ J.P. Pasternak, Environment Canada (Risk Characterization Workgroup)

The Environmental Resource Group established by Environment Canada in 1996 to assist in the environmental assessment for chloramines consisted of scientific and technical experts, including:

• S.A. Andrews, University of Waterloo
• E. Baddalo, Alberta Environment
• B. Boettger, British Columbia Ministry of Health
• M. Charlton, Environment Canada
• A. Chenard, New Brunswick Department of Environment
• W. Cheng, Environment Canada
• A. Edmonds, Ontario Ministry of Environment and Energy
• A.P. Farrell, Simon Fraser University
• L. Gammie, EPCOR Utilities Inc., Water Services
• J. Haskill, Environment Canada
• T. Ho, Ontario Ministry of Environment and Energy
• J. Jensen, State University of New York
• B. Kelso, Environment Canada
• W.B. Kindzierski, University of Alberta
• A. Kraus, Fraser Valley Regional District
• G. Kruzynski, Department of Fisheries and Oceans
• M.A. Lemke, Environment Canada
• J.S. Meyer, University of Wyoming
• D. Moore, Cadmus Group Inc.
• G. Murphy, Alberta Environment
• J.P. Pasternak, Environment Canada
• L. Powell, Environment Canada
• H. Quon, Environment Canada
• B. Raymond, Prince Edward Island Department of Technology and Environment
• S. Samis, Department of Fisheries and Oceans
• U. Schneider, Environment Canada
• F. Scully, Jr., Loyola University
• H. Singleton, British Columbia Ministry of Environment, Lands and Parks
• S.J. Stanley, University of Alberta
• K. Taylor, Environment Canada
• G. VanAggelen, Environment Canada
• M.T. Wan, Environment Canada
• R.G. Watts, Environment Canada
• D. Williamson, Manitoba Conservation
• J. Young, Prince Edward Island Department of Technology and Environment
  
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An external review of the Assessment Report and the supporting documents was conducted by:

• D. Mackay, Trent University
• M. MacLeod, Trent University
• J. Mattice, New York Sea Grant Directory
• K. Solomon, University of Guelph

A draft of the Assessment Report was made available for a 60-day public comment period (July 8 to September 6, 2000) (Environment Canada and Health Canada, 2000). Following consideration of comments received, the Assessment Report was revised as appropriate. A summary of the comments and responses is available on the Internet at:

www.ec.gc.ca/cceb1/eng/final/index_e.html

The text of the Assessment Report has been structured to address environmental effects relevant to determination of "toxic" under Paragraphs 64(a) and (b).

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/eng/final/index_e.html

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

• Commercial Chemicals Evaluation Branch
  Environment Canada
  14th Floor, Place Vincent Massey
  351 St. Joseph Blvd.
  Hull, Quebec
  K1A 0H3
  or
  Environmental Health Centre
  Room 104
  Health Canada
  Tunney's Pasture
  Ottawa, Ontario
  K1A 0L2