Registration Dossier

Administrative data

Description of key information

The analogue chemical, dimyrcetol, is a skin irritant in rabbits when tested undiluted.  The diluted material was not a skin irritant in humans.  The analogue chemical, myrcenol, dihydro derivative, is not an irritant when tested in humans at a concentration of 20%.  Dihydromyrcenol (undilted) was an eye irritant in rabbits.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Eye irritation

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (irritating)

Additional information

Skin Irritation

In a key study in rabbits, the undiluted analogue chemical, dimyrcetol, applied under semi-occlusive wrap was rated a skin irritant according to Annex V of EEC Directive 78/831 based on a group mean erythema irritation score of 2 or higher for the 24-, 48- and 72-hour observations. Minimal erythema and edema (scores of 0 to 1) persisted to the 168 hour observation. A 50% dilution in diethyl phthalate was not an irritant under the same conditions. All irritant effects noted in the study with 50% test material were resolved by the 168-hour observation point. The results from several supporting skin irritation studies with undiluted dimyrcetol or the analogue chemical, myrcenol, dihydro derivative, indicated similar irritant effects.

In a key study, the analogue chemical, myrcenol, dihydro derivative, showed no irritant effects in a repeated insult patch test when tested at a 20% concentration in human subjects (see Section 7.4.1). In similar supporting studies with dimyrcetol, concentrations ranging from 4 to 10% were not irritating to human skin.

Eye Irritation

In a key study in rabbits, 0.1 mL of undiluted dihydromyrcenol was applied to six rabbit eyes followed by examinations at 24-, 48 and 72-hours and at days 4 and 7 days following treatment. Eyes were examined with fluorescein stain under ultraviolet light at 24-hours and 7 days. Any persistent changes noted at day 7 were re-evaluated on day 10. All animals developed corneal opacity by 24 hours (scores of 1 to 2). Opacity had cleared in one animal at 72 hours and in 4 of 6 animals by day 7. The eyes of the last 2 animals cleared by day 10. Based on the Draize scoring system, the material would be rated as moderately irritating to eyes. Mean overall scores at 24-, 48- and 72-hours were as follows: opacity, 1.56; iris, 0.06; conjunctival redness, 1.44; conjunctival chemosis, 0.50; and conjunctival discharge, 0.56. In a supporting study in rabbits, undiluted dimyrcetol was rated an eye irritant based on the Draize scoring system. Mean overall scores at 24-, 48- and 72-hours were as follows: opacity, 0.33; iris, 0.17; conjunctival redness, 0.83; conjunctival chemosis, 0.56; and conjunctival discharge, 0.56.

Please refer to Section 13 of this IUCLID file for read-across documentation and rationale for the selection of representative analogue chemicals.


Effects on skin irritation/corrosion: irritating

Effects on eye irritation: irritating

Effect level: empty Endpoint conclusion: Adverse effect observed

Justification for classification or non-classification

Skin Irritation

Based on the results of the key study with the analogue chemical, dimyrcetol (group mean erythema irritation score of 2 or greater), dihydromyrcenol would be rated a primary dermal irritant under the EU DSD criteria (EU Directive 67/548/EEC). It would be assigned a Xi:R38 (Irritating to skin) rating. Dihydromyrcenol would be classified for skin irritation under the EU CLP criteria (EU Regulation 1272/2008) as irritating to skin, Category 2. According to the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN-GHS), dihydromyrcenol would be rated as a irritating to skin, Category 3.

Eye Irritation

Dihydromyrcenol would not be rated an eye irritant under the EU DSD criteria (EU Directive 67/548/EEC). This is based on mean corneal opacity scores of less than 2; mean scores for iris lesions of less than 1; mean conjunctival redness scores of less than 2.5; and mean conjunctival chemosis scores of less than 2. Dihydromyrcenol would be classified for eye irritation (Category 2) under the EU CLP criteria (EU Regulation 1272/2008) based on a mean corneal opacity score of >1. According to the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN-GHS), dihydromyrcenol would be classifed for eye irritation (Category 2A).