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Reference Manual for the WHMIS Requirements of the Hazardous Products Act and Controlled Products Regulations

CPR Section 33 - Manner of Establishing Classification

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Manner of Establishing Classification

33 (1) For the purpose of establishing that a product, material or substance is included in a class listed in Schedule II of the Act or falls into a division of a class, the supplier shall use, subject to subsection (2),

1. results from testing that he has carried out with respect to the product, material or substance in accordance with sections 34 to 66, as applicable; or
2. evidence based on established scientific principles with respect to [SOR/2010-38; s. 2]
   
   1. the product, material or substance, or
   2. where appropriate, a product, material or substance that has similar properties.

(2) For the purpose of establishing that a product, material or substance is or is not included in Class D - Poisonous and Infectious Material, the supplier may use, in place of the evidence referred to in subsection (1), one or more of the following:

1. results of other testing with respect to the product, material or substance;
2. if appropriate, results of testing with respect to a product, material or substance that has similar properties; and
3. other evidence based on studies or epidemiological data with respect to
   1. the product, material or substance, or
   2. if appropriate, a product, material or substance that has similar properties. [SOR/2010-38; s. 2]

(3) If the evidence referred to in paragraph (1)(b) results from toxicological studies, the studies shall have been carried out in accordance with [SOR/2010-38; s. 2]

1. the applicable OECD Test Guideline referred to in this Part; or [SOR/97-543; s. 20]
2. where there are no tests carried out in accordance with the applicable OECD Test Guidelines referred to in this Part, one of the following tests or methods:
   
   1. in the case of a 90 day test or a chronic test, a test or method described in U.S. Food and Drug Administration (FDA) guidelines or U.S. Environmental Protection Agency (EPA) guidelines, as published in the Federal Register and as amended from time to time,
   2. in the case of a test for skin or eye irritation, the Draize Test as described in volume 82 of The Journal of Pharmacology and Experimental Therapeutics, dated 1944, at pages 377 to 390,
   3. in the case of a test for teratogenicity, a test or method described in Principles for the Testing of Drugs for Teratogenicity, Technical Report Series Number 364, published in 1967 by the World Health Organization,
   4. in the case of a test for mutagenicity, a test or method described by the U.S. Environmental Protection Agency (EPA) in "Proposed Guidelines for Registering Pesticides in the U.S.; Hazard Evaluation: Human and Domestic Animals", as published in volume 43 of the Federal Register (No. 163), dated 1978, at pages 37,336 to 37,403, or
   5. any other test or method that is carried out in accordance with generally accepted standards of good scientific practice at the time the test is carried out.

Discussion of Section 33

To determine if a product is included in one or more WHMIS classes, the supplier must use the procedures set out in this section of the CPR. If the product is specified by the CPR to fall into one of the classes listed in Schedule II to the HPA, it is a controlled product. The term "controlled product" is defined in section 2 of the HPA. The CPR does not allow a supplier to make the choice as to whether or not the product should be classified into WHMIS. The supplier or importer of the product has the legal responsibility to determine whether the product is a controlled product.

Professional judgement: The extent to which professional judgement is used by a supplier will depend on the specific criteria being considered. The guidelines, which can be accessed from the "CLASSIFICATION" page of the Government of Canada WHMIS Web site, ( www.whmis.gc.ca ), provide guidance on the use of professional judgement in the classification of controlled products under WHMIS.

Structure-activity relationships: If no toxicological information is available for a hazardous substance, a Quantitative Structure Activity Relationship (QSAR) system may be used to obtain information about the potential toxicity of the substance. Data thus obtained can be used for the toxicological classification of a substance about which no toxicological information is available. Where a supplier has access to information generated by a QSAR system, and the information is relevant to the hazardous properties of a substance, the supplier should evaluate that information; {ref.: PIS No. 74}.

Sufficiency of evidence: The CPR does not require a supplier to research all of the literature or examine all of the tests that have been carried out. Where a supplier carries out his/her own tests pursuant to paragraph 33(1)(a), he/she must do so in accordance with sections 34 to 66 which, for the most part, set out objective tests. Where, pursuant to paragraph 33(1)(b), a supplier uses evidence based on established scientific principles, he/she must base his/her decision on a reasonable evaluation of test results. "Reasonableness" should be assessed on the basis of a reasonably competent individual, knowledgeable in the appropriate science necessary to evaluate the product, material or substance.

Testing requirements: Neither the HPA nor the CPR impose a requirement for the testing of materials in order to classify them for any of the WHMIS Classes. For example, a supplier is not obliged to conduct additional toxicological testing of a product in order to assess its potential hazard. As a fundamental principle, during the development of WHMIS, all stakeholders agreed that nothing in the hazard criteria, nor any part of WHMIS would require additional toxicological testing. Rather, the WHMIS program was designed to make the best use of existing toxicological data.

Untested mixtures: A classification system based on cut-off presumes that a mixture is hazardous if it contains a hazardous ingredient at a concentration exceeding a specified cut-off. The use of cut-offs is administratively straightforward and can be applied by using available data on the toxicology of ingredients of the mixture. The cut-off values agreed to for WHMIS are:

Since WHMIS is an information system, the use of cut-off values appeared justifiable as a means of consistently communicating information about hazardous ingredients as contrasted with providing a hazard evaluation of an untested mixture. The numerical values of the cut-offs, however, are necessarily arbitrary and were chosen largely for consistency between Canada and the United States.¹ Upon transition to the GHS in WHMIS, the cut-off values for the classification of untested mixtures for health hazards should be harmonized with those of Canada's major trading partners with no reduction in the level of worker protection.

Weight of evidence approach: Well conducted, credible studies could point to different conclusions regarding whether the product, material or substance is a controlled product. The supplier must assess the impact of deciding that the product is not a controlled product versus the impact of deciding that it is a controlled product. In the final analysis, the supplier's decision should be both reasonable (in light of the scientific evidence) and responsible (in light of the fact that the supplier is selling or importing potentially hazardous material for use in the workplace). Similar considerations are required when deciding what information should be disclosed on an MSDS. The weight of evidence approach is a cumulative and qualitative (as opposed to quantitative) evaluation of a body of data.

Definitions for "reliability", "relevance" and "adequacy" of data have been proposed in the article "A systematic Approach for Evaluating the Quality of Experimental Toxicological and Ecotoxicological Data"; (ref.: H.-J. Klimisch et. al.; Regulatory Toxicology and Pharmacology 25, 1-5 (1997); article no. RT961076).

For some of the CPR criteria, a weight of evidence approach would not be considered to be appropriate. If, for example, as per subparagraph 61(a)(i) of the CPR, an animal assay carried out in accordance with the specified test produced a response in 30 per cent of the rats tested, even if the same test conducted on mice and guinea pigs elicited responses in less than 30 per cent of each population, it is not appropriate to use a weight of evidence approach in the classification of this substance under the CPR. The three studies do not constitute "replicate studies", i.e., identical species and route. In this case, as this CPR criterion specifies "an assay", i.e., a singular assay, the supplier must consider the product as falling within the criteria for skin sensitization as the CPR criteria do not consider lesser results obtained from additional assays.

Subsection 33(1):

Subsection 33(2):

Subsection 33(3):

As for subsection 33(2), subsection 33(3) is also applicable only to Class D. In many cases toxicological testing of a product will not have been carried out in accordance with the OECD Test Guidelines referred to in the criteria for Class D. This section ensures that the wealth of toxicological information derived from testing carried out prior to the establishment of these OECD tests may still be used. However, the testing must have been carried out in accordance with generally accepted standards of scientific practice at the time it was conducted. Subparagraphs 33(3)(b)(i) to (iv) are examples of tests or methods that were considered to be "generally accepted standards of good scientific practice" when they were published. Tests or methods that have been derived from these listed tests or methods are also acceptable. Subparagraph 33(3)(b)(v) also allows the use of "any other test or method that is carried out in accordance with generally accepted standards of good scientific practice at the time the test is carried out."

The deletion of the term "test results" in paragraph 33(1)(b) through SOR/2010-38 necessitated the amendment to subsection 33(3) to replace " Where the test results referred to in paragraph (1)(b)" with " If the evidence referred to in paragraph (1)(b)...".

¹ Report of the [WHMIS] Project Steering Committee, 1985; p.14.
² Report of the [WHMIS] Project Steering Committee, 1985; page 61.