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EC number: 201-142-8 | CAS number: 78-78-4
Table 1. Incidence of Challenge in Guinea Pig - Ethanol
No. of animals
Irritation Control Group
24 hr erythema
24 hr edema
48 hr erythema
48 hr edema
Table 2. Incidence of Challenge in Guinea Pig – MRD-91-962
Table 3. Incidence of Challenge in Guinea Pig – DNCB (Positive Control)
Irritation Control Group - Acetone
Treatment Group – 0.1% DNCB in Acetone
A dermal sensitisation study was conducted in guinea pigs (20 females/dose; 15 females for positive control) using n-pentane.
Induction Phase: An area near the scapula in the mid-dorsal region of all animals was clipped on the day prior to intradermal injection of tbe test material and/or carrier. 6 intradermal injections (0.1 mL each) were administered to 3 different sites as follows: Site 1: FCA/water to treated and control groups; Site 2: 5.0% n-pentane in carrier (ethanol) to the treated group, 100% ethanol to the control group; Site 3: 5.0% n-pentane in FCA/Water to the treated group, 5.0% carrier (reverse osmosis water) in FCA/Water to the control group. On day 7 following injection, 0.5 mL of a mild to moderately irritating dose of n-pentane was administered topically over the previously injected areas and covered with occlusive wrapping. Control animals received topical carrier applications instead.
Challenge Phase: 21 days post induction phase, 0.1 mL of n-pentane (1.0% in ethanol) was applied topically to the left flank of both treated and control irritation groups. 0.4 mL of the carrier (ethanol) was applied to the right flank. All applications were kept secure under occlusive wrapping for 24 hours and animals observed for dermal effects for 48 hours.
Sensitization was evaluated by comparing the reactions of treated animals with the reactions of control animals that received a single epidermal exposure to the test material. Control responses were used to distinguish true sensitization from local irritation produced by the same concentration of test material.
All animals survived to study termination and displayed a weight gain from their day 0 values. Abnormal clinical observations during scheduled intervals were limited to one treated group animal that was emaciated and had a small amount of stool. Another animal exhibited slight emaciation and poor food consumption. Clinical signs observed in these two animals were considered to be correlated to the stress of the wrapping procedure and not treatment-related. No signs of dermal irritation were observed at any dose in either patch group. DNCB elicited positive reactions from all tested animals 24 and 48 hours after removal of the patch challenge.
Based on the lack of signs dermal irritation observed in the study, n-pentane is not considered a dermal sensitiser. This study was given a Klimisch score of 1 and classified as reliable without restriction because it is in compliance with the OCED principles of GLPs.
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