Registration Dossier

Administrative data

Description of key information

Skin irritation (similar to OECD TG 404): irritating (BASF 1983; 83/186) 
Eye irritation (OECD TG 405): not irritating (BASF 1983; 83/186)

Key value for chemical safety assessment

Additional information

Skin irritation

In the chosen key primary dermal irritation study similar to OECD TG 404, Vienna white rabbits (3 females) were dermally exposed (occlusive) to unchanged tetrahydro-2-isobutyl-4-methyl-2H-pyran for 4 hours (BASF 1983; 83/186). Mean scores (24 -72 hours) for each animal were 2.0, 2.0 and 1.7 for erythema and edema, respectively. Erythema were not reversible in all animals within 8 days after removal of the patch, i.e. end of the observation period.

In a supportive study with comparable testing protocol, 50%, 25% and 10% tetrahydro-2-isobutyl-4-methyl-2H-pyran in vaseline was dermally applied to Vienna white rabbits (2 males, 1 female) under occlusion for 4 hours (BASF 1984; 83/186). Very slight to clearly remarkable skin irritation (fully reversible within 8 days) has been observed after application of the test substance at 50% in vaseline. Very slight skin irritation (fully reversible within 48 hours) has been observed after application of the test substance at 25% in vaseline. Application of 10% test substance in vaseline showed no skin irritation.

In a supportive study according to OECD TG 404 and GLP, young adult white rabbits (3 males) were dermally exposed (semiocclusive) to unchanged structural analogue rose oxide for 4 hours (BASF 2007; BASF18H0624/072134). Rose oxide shares a high structural similarity but varies in the presence of a double bond as putative reactive structural feature. Mean scores (24 -72 hours) for each animal were 3.0, 3.0 and 3.3 for erythema respectively. Mean scores (24 -72 hours) for edema were 1.0 for each animal. Erythema were not reversible in all animals within 14 days after removal of the patch.

Overall, mean scores for erythema/edema observed were equal to 2 but not above 2.3 in the key study in 2/3 animals. The full reversibility for skin findings has not been demonstrated. Furthermore, the findings with the structurally similar rose oxide do not exclude a persistence of effects for a longer duration than examined in the key study. Therefore, tetrahydro-2-isobutyl-4-methyl-2H-pyran is considered to be irritating to skin.

Eye irritation

In the chosen key tetrahydro-2-isobutyl-4-methyl-2H-pyran has been tested in 3 Vienna white rabbits according to OECD TG 405 (BASF 1983; 83/186). Unchanged tetrahydro-2-isobutyl-4-methyl-2H-pyran was instilled into the right eye of each rabbit (0.1 mL). No effects in terms of corneal opacity and iritis have been observed. Chemosis with a score of 1 for each animal was observed at the 1 hour reading only. Mean scores of 1 for conjunctival redness (24, 48 and 72 hour observation time point) was observed for each animal but was fully reversible within 8 days.  Overall, tetrahydro-2-isobutyl-4-methyl-2H-pyran showed little eye irritation potential under the chosen testing conditions.

Justification for classification or non-classification

The present data fulfill the criteria laid down in regulation (EU) 1272/2008, and a classification "irritating to skin" (R38) and "skin irritant" (category 2) is warranted.

The present data on eye irritation do not fulfill the criteria laid down in regulation (EU) 1272/2008, and therefore, a non-classification is warranted.