Styrene - PSL1

1.0 Introduction

The Canadian Environmental Protection Act (CEPA) requires the Ministers of the Environment and 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 in 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 assessed to be "toxic" according to section 11 may be placed on Schedule I of the Act and considered for possible development of regulations, guidelines, 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.

The assessment of whether styrene is "toxic" as defined under CEPA, was based on the determination of whether it enters or is 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 effects of photochemical reaction products of styrene are not addressed in this Assessment Report but are considered in the Federal/Provincial Management Plan for nitrogen oxides ^{(NO_x) and} volatile organic compounds (VOCs) [CCME, 1990].

Data relevant to the environmental assessment of styrene were compiled in a review prepared for Environment Canada under contract by Ecological Services for Planning Ltd., Guelph, Ontario. Information cited in this review was identified through on-line searches of the following commercial databases: AGRICOLA, AQUIRE, BIOSIS, CESARS, CHEMFATE, CHEMINFO, ENVIRODAT, ENVIROFATE, HSDB, PHYTOTOX, RTECS and TOXLINE. The on-line searches were conducted in June 1991, and covered the literature published during the period between January 1985 and June 1991. Additional information was subsequently identified during the preparation of this assessment report from more recent review articles and from searches of other commercial databases, conducted in February 1992 (Pollution Abstracts and Chemical Abstracts).

For the health-related sections of this report, a background review was prepared under contract by Mann, Benford and Grasso of the Robens Institute of Health and Safety, University of Surrey, Guildford, Surrey, U.K., in November 1991. A literature survey was conducted by the contractor based on existing reviews of the toxicity of styrene (IARC, 1979, 1985, 1987; HSE, 1981; NIOSH, 1983; IPCS, 1983; U.S. EPA, 1988, 1989; Bond, 1989; Barale, 1991; Brown, 1991), supplemented by on-line searches for the years 1990 and 1991 (search completed on July 1, 1991).

To identify the toxicological data relevant to the assessment of the effects of styrene on human health, literature searches of the following databases were conducted: HSDB, RTECS, IRIS (search done in February 1991) and CCRIS (search done in May 1992). The name and registry number were searched in the TOXLINE (1981 to present) databases, and the TOXLIT (1981 to present) databases. All 1991 references were provided from TOXLINE and TOXLIT, in November 1991. In May 1992, TOXLINE was searched again for review articles; only those references published after 1987 were retrieved. As well, in May 1992, articles from the NTIS subfile that contained styrene as a key word were retrieved. In September 1991, MEDLINE was searched and articles dating back to 1990 indexed with the linked term styrene and pharmacokinetics were reviewed. NTIS and BIOSIS (dating back to 1985) were also searched. Additional relevant articles were identified during external peer review.

To identify data relevant to the estimation of exposure of the general population to styrene, literature searches were conducted in the following databases: Environmental Bibliography, ENVIROLINE, Pollution Abstracts, Chemical Exposure Database, Chemical Safety Newsbase and the Federal Register. The Canadian databases ELIAS, AQUAREF, MICROLOG and CODOC/GDOC were searched for all references to styrene. CISTIMON was also searched for references to styrene. Information on exposure is also included in some of the toxicological sources noted above, especially HSDB and TOXLINE. These sources were supplemented with manual searches of Current Contents throughout 1991 and 1992.

Additional relevant information was obtained from the Canadian Chemical Producers' Association and the Drinking Water Surveillance Program of the Ontario Ministry of the Environment.

Review articles were consulted where appropriate; however, all original studies that form the basis for determining whether styrene is "toxic" under CEPA have been critically evaluated. The following staff of Environment Canada and of Health Canada contributed to the preparation of this report:

B. Brownlee (Environment Canada)
L. Brownlee (Environment Canada)
I. Caldwell (Health Canada)
F. Chen (Environment Canada)
C. Fortin (Environment Canada)
R. Gomes (Health Canada)
K. Lloyd (Environment Canada)
M.E. Meek (Health Canada)
R. Newhook (Health Canada)
S. Savard (Health Canada)
K. Taylor (Environment Canada)

In this report, a synopsis that will appear in the Canada Gazette is presented. Section 2 is an extended summary of the technical information that is critical to the assessment. The assessment of whether styrene is "toxic" under CEPA is presented in Section 3.

As part of the review and approvals process established by Environment Canada, the environmental sections of this Assessment Report and Supporting Documentation were peer reviewed by Mr. Norman Bazinet (Ontario Ministry of the Environment, Toronto, Ontario), Dr. Otto Meresz (Ontario Ministry of the Environment, Rexdale, Ontario), Dr. Arthur Niimi (Department of Fisheries and Oceans, Burlington, Ontario) and Dr. Douglas Spry (Ontario Ministry of the Environment, Toronto, Ontario). Sections related to the effects on human health were peer reviewed by Dr. Jack Siemiatycki (Institut Armand-Frappier, Université du Québec , Laval-des-Rapides, Quebec), Dr. Ron Miller (The Dow Chemical Company, Midland, Michigan-Supporting Documentation only), Dr. Don Johnston and Dr. Flora Ratpan (Novacor Chemicals, Calgary, Alberta-Supporting Documentation only), and BIBRA Toxicology International. The health-related sections were subsequently approved by the Standards and Guidelines Rulings Committee of the Bureau of Chemical Hazards of Health Canada. The entire Assessment Report was reviewed and approved by Environment Canada/Health Canada CEPA Management Committee.

Copies of this Assessment Report and of the unpublished Supporting Documentation are available upon request from:

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

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