Priority Substances List Assessment Report- 1,3-Butadiene (Continued)

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 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 initial screening of readily accessible information, the rationale for assessing 1,3-butadiene (hereafter referred to as butadiene) provided by the Ministers' Expert Advisory Panel on the Second Priority Substances List (Ministers' Expert Advisory Panel, 1995) was as follows:

1,3-Butadiene is present at low levels in indoor and outdoor air throughout the country. Sources include motor vehicle emissions and the manufacture of plastics and synthetic rubbers. The substance is carcinogenic and genotoxic in animals. It may be carcinogenic in humans. It is important to assess the potential risk to human health and the environment.

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) 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 Internet 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 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 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 and 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 the assessment of entry, environmental fate and exposure and potential effects on the environment (prior to March 1998) and human health (prior to April 1998 for toxicity information) are presented in Appendix A. Although much of the research on butadiene has been conducted outside Canada, available data on sources, use patterns and fate of butadiene in the Canadian environment have been emphasized. Review articles were consulted where appropriate. However, all original studies that form the basis for determining whether butadiene is "toxic" under CEPA 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).

Sections of the Assessment Report and the supporting documentation (Environment Canada, 1998) related to the environmental assessment of butadiene were prepared or reviewed by the members of the Environmental Resource Group established by Environment Canada to support the environmental assessment:

A. Bobra, AMBEC Environmental Consultants (coordinator for the environmental assessment)
Y. Bovet, Environment Canada
N. Bunce, University of Guelph
R. Chénier, Environment Canada (lead for the environmental assessment)
T. Dann, Environment Canada
F. Edgecomb, Canadian Plastics Industry Association
P. Georges, Environment Canada
R. Keefe, Imperial Oil Ltd.
F. Onuska, Environment Canada
F. Ratpan, Nova Chemicals
G. Rideout, Environment Canada
A. Stelzig, Environment Canada
M. Tushingham, Environment Canada
C.J. West, Bayer Rubber Inc.

The sections of the Assessment Report and supporting documentation relevant to the environmental assessment were also reviewed by:

S. Abernethy, Ontario Ministry of the Environment
L. Brownlee, Environment Canada
P. Makar, Environment Canada
L. McCarty, L.S. McCarty Scientific Research & Consulting (who also prepared a first draft of the environmental sections of the Assessment Report)
S. Robertson, U.K. Environment Agency
J. Schaum, U.S. Environmental Protection Agency
A. Sergeant, U.S. Environmental Protection Agency
G. Whitten, Systems Application International

Sections of this Assessment Report and supporting documentation related to health were prepared, based, in part, on background information prepared in 1994 by BIBRA International, by the following staff of Health Canada:

R. Beauchamp
K. Hughes
M.E. Meek
D. Moir
M. Walker

Sections of the Assessment Report and supporting documentation on genotoxicity and reproductive and developmental toxicity were reviewed by D. Blakey and W. Foster, respectively, of the Environmental and Occupational Toxicology Division of Health Canada. A review of the exposure assessment included in the critical epidemiological studies was prepared under contract by M. Gerin and J. Siemiatycki of the Institut Armand-Frappier, University of Quebec.

In the first stage of external review, sections of the supporting documentation pertaining to human health were considered by the following individuals, primarily to address adequacy of coverage:

J. Aquavella, Monsanto Company
M. Bird, Exxon Biomedical Sciences, Inc.
J.A. Bond, Chemical Industry Institute of Toxicology
I. Brooke, U.K. Health and Safety Executive
G. Granville, Shell Canada Ltd.
R. Keefe, Imperial Oil Ltd.
A. Koppikar, U.S. Environmental Protection Agency
R.J. Lewis, Exxon Biomedical Sciences, Inc.
K. Peltonen, Finnish Institute of Occupational Health
F. Ratpan, Nova Chemicals

In the second stage of external review, accuracy of reporting, adequacy of coverage and defensibility of conclusions with respect to hazard characterization and exposure-response analyses were considered in written review by BIBRA International and the following individuals:

R.J. Albertini, University of Vermont
J.A. Bond, Chemical Industry Institute of Toxicology
I. Brooke, U.K. Health and Safety Executive
J. Bucher, U.S. National Toxicology Program
B. Davis, U.S. National Toxicology Program
E. Delzell, University of Alabama at Birmingham
B.J. Divine, Texaco
A.A. Elfarra, University of Wisconsin-Madison
E. Frome, Oak Ridge National Laboratory
B.D. Goldstein, Environmental and Occupational Health Sciences Institute
R.F. Henderson, Lovelace Respiratory Research Institute
R.D. Irons, University of Colorado Health Sciences Center
A. Koppikar, U.S. Environmental Protection Agency
J. Lubin, National Cancer Institute
J. Lynch, Exxon Biomedical Sciences, Inc. (retired)
R.L. Melnick, U.S. National Toxicology Program
K. Peltonen, Finnish Institute of Occupational Health
A.G. Renwick, University of Southampton
J. Siemiatycki, Institut Armand-Frappier L.T. Stayner, U.S. National Institute for Occupational Safety and Health J.A. Swenberg, University of North Carolina
R. Tice, Integrated Laboratory Systems, Inc.
J.B. Ward, Jr., University of Texas Medical Branch

In the third and final stage of external review, adequacy of incorporation of the comments received during the second stage was considered at a final meeting of a panel of the following members convened by Toxicology Excellence in Risk Assessment (TERA) in November 1998:

H. Clewell, K.S. Crump Division of ICF Kaiser
M.L. Dourson, TERA
L. Erdreich, Bailey Research Associates, Inc.

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

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 (October 2 to December 1, 1999) (Environment Canada and Health Canada, 1999). Following consideration of comments received, the Assessment Report was revised as appropriate. A summary of the comments and their 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, 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