Priority Substances List Assessment Report for Chloroform

1.0 Introduction

The Canadian Environmental Protection Act, 1999 (CEPA 1999) requires the federal Ministers of 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 should be given priority to determine whether they are 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 are 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 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 an initial screening of readily accessible information, the rationale for assessing chloroform provided by the Ministers' Expert Advisory Panel on the Second Priority Substances List (Ministers' Expert Advisory Panel, 1995) was as follows:

Chloroform is present in drinking water, food and indoor and outdoor air. Chloroform is imported for a variety of industrial applications and is generated in large quantities as a byproduct of water chlorination.

Most environmental releases from industrial uses are to the atmosphere. Chloroform is carcinogenic and genotoxic in animals and there is some evidence that it is carcinogenic in humans. Information on this substance has been gathered, reviewed and evaluated by an international group of experts. An assessment is needed to characterize the level of exposure and the associated risks to human health and the environment in Canada.

Descriptions of the approaches to assessment of the effects of Priority Substances on the environment and human health are available in published companion documents. 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 Commercial Chemicals Evaluation Branch web site 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 approach to the assessment of effects on human health is outlined in the following publication of the Environmental Health Directorate of Health Canada: "Canadian Environmental Protection Act - Human Health Risk Assessment for Priority Substances" (Health Canada, 1994), copies of which are available from:

• Environmental Health Centre
  Room 104
  Health Canada
  Tunney's Pasture
  Ottawa, Ontario
  K1A 0L2

or on the Environmental Health Directorate publications web site (www.hc-sc.gc.ca/ehp/ ehd/catalogue/bch.htm). The approach is also described in an article published in the Journal of Environmental Science and Health -Environmental Carcinogenesis & Ecotoxicology Reviews (Meek et al., 1994). It should be noted that the approach outlined therein has evolved to incorporate recent developments in risk assessment methodology, which are described on the Environmental Substances Division web site (www.hc-sc.gc.ca/ehp/ehd/bch/env_contaminants/psap/psap.htm) and which will be addressed in future releases of the approach paper for the assessment of effects on human health.

The search strategies employed in the identification of data relevant to assessment of potential effects on the environment (prior to July 1999) and human health (prior to October 1999) are presented in Appendix A. Review articles were consulted where appropriate. However, all original studies that form the basis for determining whether chloroform is "toxic" under CEPA 1999 have been critically evaluated by staff of Environment Canada (entry and environmental exposure and effects) and Health Canada (human exposure and effects on human health).

The environmental sections of this report were produced by D. Moore and L. Pirie of the Cadmus Group, Inc. on behalf of Environment Canada and were revised by D. Caldbick and K. Taylor, Environment Canada. They were reviewed by the following members of the Environmental Resource Group, established by Environment Canada to support the environmental assessment:

• P. Doyle, Environment Canada
• W. Hayes, Dow Chemical
• K. Kaiser, Environment Canada

Environmental sections of the Assessment Report and the environmental supporting documentation (Environment Canada, 1999a) were also reviewed by internal reviewers at Environment Canada - namely, P. Cureton and D. Dubé - as well as by external reviewers:

• Averill, Water Technology International Corporation
• W.J. Birge, University of Kentucky
• N. Bunce, University of Guelph
• D.B. Carlisle, Brez-Carlisle Inc.
• L. Gammie, AQUALTA
• D. Gessford, Dow Chemical Company
• M.D. Kercher, University of Kentucky
• D.J. Price, University of Kentucky
  
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The health-related sections of this Assessment Report are based in part on the deliberations of two expert groups, in which staff of Health Canada participated. These were a Task Group on chloroform of the International Programme on Chemical Safety (IPCS) (WHO, 1994) and an Expert Panel convened by the International Life Sciences Institute (ILSI) to develop case studies for chloroform and dichloroacetic acid in the context of the revised cancer guidelines released in 1996 by the U.S. Environmental Protection Agency (EPA) (ILSI, 1997).

The IPCS monograph on the health effects of chloroform was published in 1994. The first draft was prepared by Dr. J. de Fouw of the National Institute of Public Health and Environmental Protection, Bilthoven, Netherlands, and subsequently circulated to IPCS focal points for comment. The revised draft was subsequently finalized at a meeting of the following Task Group members, held in Geneva on November 15-19, 1993:

• M.W. Anders, University of Rochester, Rochester, New York, USA
• Anderson, British Industrial Biological Research Association, Surrey, United Kingdom
• R.J. Bull, Washington State University, Pullman, Washington, USA
• C.D. Carrington, Food and Drug Administration (FDA), Washington, D.C., USA
• M. Crookes, Building Research Establishment, Watford, United Kingdom
• J. de Fouw, National Institute of Public Health and Environmental Protection, Bilthoven, Netherlands (Rapporteur)
• E. Elovaara, Institute of Occupational Health, Helsinki, Finland
• M.E. Meek, Health Canada, Ottawa, Canada (Chair)
• Pegram, U.S. EPA, Research Triangle Park, North Carolina, USA
• S.A. Soliman, King Saud University-Al-Qasseem, Bureidah, Saudi Arabia
• Vittozzi, Istituto Superiore di Sanita, Rome, Italy
• P.P. Yao, Chinese Academy of Preventive Medicine, Beijing, China

The ILSI Expert Panel, which first met in September 1996, was composed of the following members:

• M. Andersen, ICF Kaiser International (Chair)
• G. Boorman, National Institute of Environmental Health Sciences
• D. Brusick, Covance Laboratories, Inc.
• S. Cohen, University of Nebraska Medical Center
• Y. Dragan, McArdle Laboratory for Cancer Research
• C. Frederick, Rohm & Haas Company
• J. Goodman, Michigan State University
• G. Hard, American Health Foundation
• M.E. Meek, Health Canada
• E. O'Flaherty, University of Cincinnati

The final draft of the Expert Panel report on chloroform was reviewed externally by:

• C. Klaassen, University of Kansas Medical Center
• R. Melnick, National Institute of Environmental Health Sciences
• L. Rhomberg, Harvard Center for Risk Analysis

The outcome of these assessments has been updated and considered in the context of the approach to assessment of "toxic" under Paragraph 64(c) of CEPA 1999. In addition, the physiologically based pharmacokinetic (PBPK) model for animals included in ILSI (1997) was refined and a human component developed by the K.S. Crump Group (ICF Kaiser, 1999).

The content of the health-related sections of this Assessment Report and the supporting documentation (Health Canada, 1999) were prepared by the following staff of Health Canada:

• R. Beauchamp
• G. Long
• M.E. Meek
• D. Moir
• L. Turner
• M. Walker

The section related to genotoxicity was reviewed by D. Blakey, Environmental and Occupational Toxicology Division. The PBPK model incorporated herein was reviewed externally by M. Gargas, ChemRisk, McLaren Hart Inc.

The health-related sections on toxicity in the Assessment Report were reviewed externally by:

• M. Andersen, Colorado State University
• B. Butterworth, Chemical Industry Institute of Toxicology
• J. Wiltse, Office of Water, U.S. EPA
• D. Wolf, National Health and Environmental Effects Research Laboratory, U.S. EPA

The health-related sections of the Assessment Report were reviewed and approved by the Health Protection Branch Risk Management meeting of Health Canada.

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

A draft of the Assessment Report was made available for a 60-day public comment period (June 3 to August 2, 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 initially (relevant to determination of "toxic" under Paragraphs 64(a) and (b)), followed by effects on human health (relevant to determination of "toxic" under Paragraph 64(c)).

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 (Environment Canada, 1999a; Health Canada, 1999), 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