Priority Substances List Assessment Report for Non-pesticidal organotin compounds

1.0 Introduction

The Canadian Environmental Protection Act (CEPA) requires the Minister of the Environment and the Minister of National Health and Welfare 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 to be "toxic" according to this Section 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 non-pesticidal organotin compounds considered in this assessment are presented in Table 1. They are primarily those of monomethyltin, dimethyltin, monobutyltin, dibutyltin, mono-octyltin and dioctyltin. The assessment of whether non-pesticidal organotin compounds are "toxic" was based on the determination of whether they enter or may enter the Canadian environment in concentrations or quantities that could lead to exposure of humans or other biota to the extent that adverse effects could result.

Data relevant to the assessment of whether non-pesticidal organotin compounds are "toxic" to the environment under CEPA were obtained from original and review articles published up to April, 1992 (data obtained after this date were not considered for inclusion in this assessment). These articles were identified from primary journal searches, as well as searches of the following abstracting services and databases: Chemical Abstracts, Biological Abstracts, ENVIROLINE, TOXLINE, TOXLIT, U.S. National Institute for Occupational Safety and Health's Registry of Toxic Effects of Chemical Substances (RTECS), CURRENT CONTENTS, U.S. Environmental Protection Agency Toxic Releases Inventory, and Corpus Information Services. Information was also obtained from the CEPA Domestic Substances List and from Statistics Canada.

To identify the toxicological data relevant to the assessment of effects on human health, literature searches of the following electronic databases were conducted: Hazardous Substances Data Bank (HSDB, U.S. National Library of Medicine), Registry of Toxic Effects of Chemical Substances (RTECS, U.S. National Institute for Occupational Safety and Health), Integrated Risk Information System (IRIS, U.S. Environmental Protection Agency), Chemical Carcinogenesis Research Information System (CCRIS, U.S. National Cancer Institute), TOXLINE (1981 to present; U.S. National Library of Medicine), the TOXLINE backfile (1965 to 1980), TOXLIT (1981 to present), and TOXLIT (U.S. National Library of Medicine) backfile. The EMBASE database (online version of Excerpta Medica) was searched (for 1973 to present) using a "hedge" to cover toxicological information.

To identify data relevant to the estimation of exposure of the general population to non-pesticidal organotin compounds, literature searches of the following electronic databases were conducted: Environmental Bibliography (Environmental Studies Institute, California), ENVIROLINE (R.R. Bowker, New York), POLLUTION ABSTRACTS (Cambridge Scientific Abstracts, Maryland), and Food Science and Technology Abstracts (International Food Information Service, England) back to 1980, and the complete files of ELIAS (Environment Canada's Departmental Library Catalogue and collection from Fisheries and Oceans Canada), AQUAREF (Ecosystem Sciences and Evaluation Directorate, Environment Canada), MICROLOG (Micromedia, Canadian Research Index), Cooperative Documents Project databases, University of Guelph (CODOC/GDOC), and Canada Institute for Scientific and Technical Information (CISTIMON). Information on exposure is also included in some of the toxicological sources noted above, especially HSDB, TOXLINE, and EMBASE.

A background report prepared by Nieboer and Bryant (1992) under contract to Health and Welfare Canada was consulted to identify information relevant to the assessment of effects of non-pesticidal organotin compounds on human health. The following external organizations were contacted to identify data relevant to estimation of exposure of the Canadian population to non-pesticidal organotin compounds: the Ontario Ministry of the Environment (Graham, 1992); Alberta Environment (Halina, 1992); Scepter/Canron Inc. (Lister, 1992); and the National Sanitation Foundation International (Kenel, 1992).

Data relevant to the assessment of whether non-pesticidal organotin compounds are "toxic" to human health obtained after completion of these sections of this report (i.e., June 1992) were not considered for inclusion. Nonvalidated studies of Industrial Bio-Test Laboratories Inc. identified during the survey of the scientific literature were noted, but were not used in assessing whether non-pesticidal organotin compounds are "toxic" under CEPA.

Available data are insufficient to serve as a basis for estimating exposure of the general population to any of the non-pesticidal organotin compounds. Therefore, this assessment focuses principally on the environmental effects of these compounds.

Although review articles were consulted where considered appropriate, all original studies that form the basis for the determination of "toxic" under CEPA have been critically evaluated by the following Environment Canada staff (effects on the environment) and Health and Welfare Canada staff (effects on human health):

Environment Canada

• R.J. Maguire

Health and Welfare Canada

• G. Long
• M.E. Meek
• S. Savard

In this report, a synopsis that will appear in the Canada Gazette is presented. In addition, an extended summary of the technical information that is critical to the assessment is presented in Section 2.0. The assessment of whether non-pesticidal organotin compounds are "toxic" under CEPA is presented in Section 3.0. Supporting documentation that discusses the technical information in greater detail has also been prepared and is available upon request.

As part of the review and approvals process established by Environment Canada, the environmental sections of this Assessment Report were reviewed by Dr. C.H. Farr, Atochem North America, King of Prussia, Pennsylvania. The health-related sections of this Assessment Report were approved by the Standards and Guidelines Rulings Committee of the Bureau of Chemical Hazards of Health and Welfare Canada. The final Assessment Report was reviewed and approved by the Environment Canada/Health and Welfare Canada CEPA Management Committee.

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

Commercial Chemicals Branch
Environment Canada
14th Floor, Place Vincent Massey
351 Saint-Joseph Boulevard
Hull, Quebec,
Canada
KIA 0H3

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