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Administrative data

Description of key information

Cited from SIAR for SIAM 23 (Jeju, Korea, October 17-20, 2006):
"In two studies performed according to OECD TG 404, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate was found to be corrosive to the rabbit skin. Strong irritation was observed in rabbit eyes when tested according to OECD TG 405. The toxicity studies indicate that 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate vapor causes irritation of the upper respiratory tract" (see chapter 7.2.2 and 7.5.3 of IUCLID5 data set). "In a study with volunteers, a perception threshold for irritation of 0.64 mg/m3 was determined for short-term (1-5 minutes) exposure to 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate." (see chapter 7.10.5 of IUCLID5 data set)

Key value for chemical safety assessment

Additional information

Partly cited from SIAR for SIAM 23 (Jeju, Korea, October 17-20, 2006):

Skin Irritation

Studies in Animals

"Two studies on the skin irritating properties of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate were performed according to OECD TG 404. Undiluted test substance was applied in both studies." In one study with three rabbits per sex exposed occlusively for four hours, the result was, with regard to the irritation index (6.87 of max. 8.0), described as “highly irritating” (Hüls AG, 1984). "The overall result was “corrosive” because of extensive irreversible tissue damage such as necrosis, ulceration, or scarring within the observation period (14 days) in all animals. This overall assessment was confirmed by another study performed according to OECD TG 404 with one rabbit exposed semiocclusively for four hours, the result was “corrosive” with an irritation index of 4.5 of max. 8.0 (Krötlinger, 1994)."

Eye Irritation

Studies in Animals

Conflicting results ranging from “not irritating” (Hüls AG, 1984 ) to “highly irritating” (Schreiber, 1981) were reported for the effects of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate on rabbit eyes in studies performed according to OECD TG 405. The exudation observed in the study of Hüls AG (1984 ) may have contributed to the avoidance of damage to the eye. "The irritation index was 9.96 of max. 110. Ten days after treatment with 0.1 ml undiluted test substance all animals in this study showed loss of hair around the eye and incrustation at the eyelid, mostly associated with thickening on day 13, which is not reflected in the scores. In the study of Schreiber (1981), where both eyes were treated (0.1 ml undiluted per eye) and only one eye was rinsed, severe irritation of the conjunctiva was observed. There was a constantly high degree of chemosis throughout the 8 days observation period both on rinsed and non-rinsed eyes, and slight cornea damage, to a lesser degree on the rinsed eye, with significant retrogression within 8 days. The irritation score was 36.4/110 (not rinsed) or 26.4/110 (rinsed eye)."

Respiratory Tract Irritation

Studies in Animals

Some studies were performed to determine the concentration causing a 50% decrease in respiration rate. This effect, which is thought to reflect the respiratory tract irritation, was observed at 11.1 mg/m³ (30 min), 10.3 mg/m3(1 h) and 4.7 mg/m³ (3 h) in rats (MobayChemical Corporation, 1984) and at 11.1 mg/m³ (30 min), 6.0 mg/m³ (1 h) and 2.0 mg/m3(3 h) (MobayChemical Corporation_2, 1984) or 6.0 mg/m³ (3 min), 4.0 mg/m³ (10 min) and 3.0 mg/m3(30 min) (E.I. du Pont de Nemours and Company, 1987 and 1990) in mice (see chapter 7.2.2 of IUCLID 5 data set).

Studies in Humans

"Henschler (1972) published results of experiments with volunteers exposed for 1 - 5 minutes to an aerosol (with regard to the vapor saturation concentration at ambient temperature the particle concentration should be negligible in relation to vapor atmosphere) of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate. At 0.25 mg/m3the odor was just perceptible; at 0.64 mg/m3slight irritation of the mucous membranes of the eyes and nose were observed; at 1.37 mg/m3there was strong, intolerable irritation of the mucous membranes of the eyes and the breathing passages." (see chapter 7.10.5 of IUCLID data set)

Justification for classification or non-classification

The substance 3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate is classified according to the criteria of EC Directive 67/548/EEC (Annex I) as follows: "Irritating to eyes, respiratory system and skin" (Xi; R 36/37/38)