Cadmium and its compounds - PSL1

1.0 Introduction

The Canadian Environmental Protection Act (CEPA) requires the Minister of the Environment and the Minister of Health to prepare and publish a Priority Substances List 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" as defined under Section 11 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

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

Substances that are assessed as "toxic" as defined under Section 11 may be placed on Schedule I of the Act. Consideration can then be given to developing regulations, guidelines, or codes of practice to control any aspect of these substances' life cycle, from the research and development stage, through manufacture, use, storage, transport, and ultimate disposal.

The substance "cadmium and its compounds" is included on the Priority Substances List. The assessment of whether "cadmium and its compounds" are "toxic", as defined under CEPA, was based on the determination of whether they enter or are likely to enter the Canadian environment in a concentration or quantities or under conditions that could lead to exposure of humans or other biota at levels that could cause adverse effects.

The assessment of "cadmium and its compounds" as a Priority Substance under Section 11 of CEPA has been limited to inorganic cadmium compounds. [There is no evidence that organocadmium compounds, in which the metal is bound covalently to carbon, occur in nature (WHO, 1992a), and elemental cadmium is rare, and will be oxidized to cadmium oxide in the environment.] The data presented in this report have also been restricted primarily to those cadmium compounds for which it is considered that there is sufficient information on their toxicity to conduct an assessment and that are known to be present in the environment, namely cadmium oxide, cadmium chloride, cadmium sulphate, and cadmium sulphide. (Data on other cadmium compounds have been included in the supporting documentation for "cadmium and its compounds" from both Departments.) Although to the extent possible, the toxicity of these individual cadmium compounds is addressed, the available data do not permit an assessment of exposure to individual cadmium compounds in the general environment. When additional data on the speciation of cadmium in the environment has been obtained, as is suggested in Section 4.0 of this report, it may be possible to address individual compounds more fully. The term "cadmium" in this report refers to total inorganic cadmium, unless otherwise specified.

Data relevant to the assessment of whether cadmium and its compounds are "toxic" to the environment were identified through searches of commercial and government data bases (1986 to 1990) including: Pollution Abstracts, CAB, BIOSIS, AQUAREF, TOXLINE, AQUIRE, ASFA, and Chemical Evaluation Search and Retrieval System (CESARS). Manual searches of pre-1986 to September 1993 issues of 68 scientific journals were also conducted, and provincial and federal agencies were contacted through the Federal-Provincial Advisory Committee on Environment. Data relevant to the assessment of whether cadmium and its compounds are "toxic" to the environment obtained after September 1993 were not considered for inclusion.

For the health-related sections, an extensive background review of the toxicological and epidemiological data was submitted under contract by BIBRA Toxicology International, Carshalton, Surrey, U.K. in March 1992. A literature survey was conducted by the contractor based on existing reviews of the toxicity of cadmium (IARC, 1987a;b; ATSDR, 1987; 1991; CEC, 1989; WHO, 1989; HSE, 1991), supplemented by key papers from the BIBRA toxicity data base and manual searches of primary, secondary, and tertiary hardcopy sources. In addition, to identify more recent toxicological data relevant to the preparation of this assessment, a literature search was conducted in January 1993 in the TOXLINE data base for 1992 only.

To identify data relevant to the estimation of exposure of the general population to cadmium, literature searches for cadmium levels in the environment were conducted in March 1991 on the following data bases: Environmental Bibliography (1989 to 1991 only), ENVIROLINE, Pollution Abstracts (1989 to 1991), MICROLOG, Cooperative Documents Project (CODOC), and Environment Canada Departmental Library Catalogue (ELIAS). Searches were also conducted in March of 1992 for information on levels of cadmium in human tissues and fluids, and on the metabolism of cadmium, on the following data bases: DIALOG (to 1966), BIOSIS (to 1969), CODOC, Canada Institute for Scientific and Technical Information (CISTIMON), ELIAS, and Medline (to 1989).

Additional relevant information was obtained from the Drinking Water Surveillance Program of the Ontario Ministry of the Environment, the Brunswick Mining and Smelting Corporation in New Brunswick, Cominco Metals of Trail, British Columbia, Noranda Copper Smelting and Refining at Rouyn-Noranda, Quebec, and the Manitoba Department of Environment.

These sources were supplemented with manual searches of Current Contents throughout 1992 and the first half of 1993. Data identified following the period of peer review of the section related to assessment of effects on human health (i.e., September, 1993) were not considered for inclusion.

As part of the review and approvals process established by Environment Canada for its contributions to assessment reports, environmental sections of this document were reviewed by: Dr. Leah Bendell-Young (University of Ottawa), Dr. Uwe Borgmann (Fisheries & Oceans Canada), Dr. Scott Brown (Fisheries & Oceans Canada), Dr. Matt John (Agriculture Canada), Dr. Jack Klaverkamp (Fisheries & Oceans Canada), Dr. Dianne Malley (Fisheries & Oceans Canada), Dr. Sankar Ray (Fisheries & Oceans Canada), Dr. Rudolph Wagemann (Fisheries & Oceans Canada), and Dr. Norman Yan (Ontario Ministry of the Environment).

The risk assessment and the supporting documentation related to the effects on human health of cadmium and its compounds were externally peer reviewed by Dr. Bob Goyer (Chapel Hill, NC), Dr. David Bayliss (Epidemiologist, United States Environmental Protection Agency, Washington, DC), Dr. William Coker (Geological Survey of Canada; supporting documentation only), BIBRA Toxicology International (risk assessment only), and Mr. Hennie Veldhuizen (Noranda Minerals Inc., Toronto, Ont.; supporting documentation only) and the Mining Association of Canada (supporting documentation only). The Assessment Report and supporting documentation related to the effects on human health were subsequently approved by the Standards and Guidelines Rulings Committee of the Bureau of Chemical Hazards of Health Canada.

Review articles were consulted where appropriate. However, all original studies that form the basis for determining whether cadmium and its compounds are "toxic" under CEPA have been critically evaluated by the following Health Canada staff (human exposure and effects on human health) and Environment Canada staff (entry, environmental exposure and effects):

Environment Canada

• R.A Kent (task group leader)
• M.A. Lewis
• J. MacLatchy
• A.O. Mudroch
• E.L. Porter
• A.M. Scheuhammer
• U.A. Schneider

Health Canada

• J. Argo
• P. Chan
• W. Dormer
• R. Liteplo
• G. Long
• M.E. Meek
• R. Newhook

In this report, a synopsis concerning "cadmium and its compounds" that will appear in the Canada Gazette is presented. Section 2.0 is an extended summary of the technical information that is the basis of the assessment. The assessment of whether cadmium and its compounds are "toxic" is presented in Section 3.0. Supporting documentation that presents the technical information in greater detail has also been prepared.

Copies of this Assessment Report and the unpublished supporting documentation are available upon request from:

Commercial Chemicals Branch
Environment Canada
14^th Floor,
Place Vincent Massey
351 St. Joseph Blvd.
Hull, Quebec
K1A 0H3

Bureau of Chemical Hazards
Health Canada
Room 104,
Environmental Health Centre
Tunney's Pasture
Ottawa, Ontario
K1A 0L2