1 For the purposes of section 26 and paragraph 29(d) of these Regulations, a substance or stuffing material is irritant if human experience data or data obtained from testing performed in accordance with the test methods set out in this Schedule demonstrate that it is irritant to the eye or skin.
Method for Testing Eye-Irritant Properties
2 (1) Use six albino rabbits for each test substance or stuffing material. Ensure that animal facilities for such procedures are designed and maintained so as to exclude sawdust, wood chips or other extraneous materials that might produce eye irritation. Examine both eyes of each rabbit before testing. Use only those rabbits without eye defects or irritation. Hold the rabbit firmly but gently until it is quiet. Place the test substance or stuffing material in one eye of each rabbit by gently pulling the lower lid away from the eyeball to form a cup into which the test substance or stuffing material is dropped. Gently hold the lids together for one second and then release the rabbit. The other eye, remaining untreated, serves as a control. For testing liquids, use 0.1 ml (2 drops) of the test substance or stuffing material. For testing solids or pastes, use 100 mg (1.5 grains) of the substance or stuffing material. For substances or stuffing materials in flake, granule, powder or other particulate form, use the amount that has a volume of 0.1 ml (2 drops) (after compacting as much as possible without crushing or altering the individual particles, such as by tapping the measuring container) whenever this volume weighs less than 100 mg (1.5 grains). In such a case, record the weight of the 0.1 ml (2 drops) test dose. Do not wash the eyes after instillation of the test substance or stuffing material except as noted in subsection (2).
(2) Examine the eyes and record the grade of ocular reaction at 24, 48 and 72 hours. Use a binocular loupe, hand-held slit lamp or other expert means to facilitate observing the reactions. After the observations are recorded at 24 hours, the eyes may be further examined after fluorescein is applied. To do this, drop 0.05 ml (one drop) of fluorescein sodium ophthalmic solution U.S.P. or equivalent directly on the cornea. After the excess fluorescein is flushed out with sodium chloride solution U.S.P. or equivalent, injured areas of the cornea appear yellow. This is best visualized in a darkened room under ultraviolet illumination. The eyes may be washed with sodium chloride solution U.S.P. or equivalent after the 24-hour recording.
(3) A rabbit is considered to exhibit a positive reaction if, at any of the observations, the test substance or stuffing material has produced one or more of the following reactions:
(a) an ulceration of the cornea, other than a fine stippling;
(b) an opacity of the cornea, other than a slight dulling of the normal lustre;
(c) an inflammation of the iris, other than a slight deepening of the folds (or rugae) or a slight circumcorneal injection of the blood vessels;
(d) an obvious swelling in the conjunctivae (excluding the cornea and iris) with partial eversion of the lids or a diffuse crimson-red with individual vessels that are not easily discernible.
(4) The test is positive if four or more of the rabbits in the test group exhibit a positive reaction. If only one rabbit exhibits a positive reaction, the test is considered negative. If two or three rabbits exhibit a positive reaction, repeat the test using a different group of six rabbits. The second test is positive if three or more of the rabbits exhibit a positive reaction. If only one or two rabbits in the second test group exhibit a positive reaction, repeat the test with a different group of six rabbits. If a third test is needed, the substance or stuffing material is irritant if any rabbit exhibits a positive reaction.
Method for Testing Skin-Irritant Properties
3 (1) Measure primary irritation to the skin by means of a patch-test technique on the abraded and intact skin of an albino rabbit clipped free of hair. Use a minimum of six rabbits. Introduce the test substance or stuffing material — 0.5 ml (10 drops) in the case of liquids or 0.5 g (7-8 grains) in the case of solids or semisolids — under a square patch that is made up of two layers of surgical gauze measuring 25 mm by 25 mm (1 inch by 1 inch). Dissolve solids in an appropriate solvent and apply the solution as in the case for liquids. Immobilize the rabbits and secure the patches in place with adhesive tape. Wrap the entire trunk of the rabbit with an impervious material such as rubberized cloth for the 24-hour period of exposure. This material aids in maintaining the test patches in position and retards the evaporation of volatile substances or stuffing materials.
(2) After 24 hours of exposure, remove the patches and evaluate the reactions on the basis of the designated values in the following table:
Evaluation of Skin Reactions
Item Skin reaction ValueFootnote for Evaluation of Skin Reactions1 1 Erythema and eschar formation
(a) No erythema
(b) Very slight erythema (barely perceptible)
(c) Well-defined erythema
(d) Moderate to severe erythema
(e) Severe erythema (beet redness) to slight eschar formation (injuries in depth)
4 2 Edema formation
(a) No edema
(b) Very slight edema (barely perceptible)
(c) Slight edema (edges of area well defined by definite raising)
(d) Moderate edema (raised approximately 1 mm (0.04 inch)
(e) Severe edema (raised more than 1 mm (0.04 inch) and extending beyond the area of exposure)
Return to footnote 1The value recorded at each observation is the average value for the six or more rabbits subjected to the test.
(3) Repeat the observations at the end of a total of 72 hours (48 hours after the first observation). Make an equal number of exposures on areas of skin that have been previously abraded. Ensure that the abrasions are minor incisions through the stratum corneum (horny layer of the epidermis), but not sufficiently deep so as to disturb the derma or to produce bleeding. Evaluate the reactions of the abraded skin at 24 hours and 72 hours, as set out in subsection (2). Add the values for erythema and eschar formation at 24 hours and at 72 hours for intact skin to the values for abraded skin at 24 hours and at 72 hours (four values). Similarly, add the values for edema formation at 24 hours and at 72 hours for intact and abraded skin (four values). Divide the total of the eight values by four to obtain the primary irritation score. A score of five or more indicates that the substance or stuffing material is irritant.
4 For the purposes of section 26 of these Regulations, a substance is corrosive if it causes visible destruction or irreversible damage in tissue at the site of the application.
5 For the purposes of section 26 of these Regulations, a substance is sensitizing if human experience data demonstrate that it causes an allergenic sensitization in a substantial number of humans who come into contact with it.
- SOR/2016-302, s. 9.
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