Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Additional information:

The potential for 2,2,4-trimethyl-1,3-pentanediol to cause dermal sensitization was evaluated based on one key and three supporting studies in which the test material in various solvents was applied epicutaneously to the clipped backs of guinea pigs. The test material was periodically reapplied to the guinea pig backs for two weeks and average irritation scores for treated and control animals were compared 24 and 48 hours after the last application. The test method used in these studies is not one of the recognized and officially accepted animal test methods outlined in current regulatory guidelines. However, when the tests are evaluated together, they provide evidence that the test material has a low potential to cause dermal sensitization. In the key study which used a 1% mixture of the test material in a 1:1:3 acetone:dioxane:guinea pig fat vehicle, ten animals were repeatedly treated with the test mixture while five animals each received the vehicle or positive control. Two of the ten treated animals showed a weak response. The average final irritation score in the test group was 1.6 48 hours after the final application compared to average scores of 1.1 and 3.2 for the vehicle and positive control groups, respectively. In the first supporting study, groups of five guinea pigs were repeatedly exposed to either 0.1M test material in a 1:1:3 acetone:dioxane:corn oil vehicle, vehicle alone, or the positive control substance phenylhydrazine. Under the conditions of the study, 2,2,4-trimethyl-1,3-pentanediol did not cause a significant increase in average irritation score when compared to the controls.  In the second supporting study, four animals were treated with a 40% solution of the test material in ethanol while five animals were treated with solvent alone and three animals were treated with phenylhydrazine. 2,2,4-Trimethyl-1,3-pentanediol did not produce a positive response based on an average final irritation score of 1.1 compared to 1.0 for the vehicle control. In the third supporting study, guinea pigs were repeatedly treated with 10% of a stock solution of 40% TMPD:40% ethanol:20% water in an acetone: dioxane:guinea pig fat vehicle. Average irritation scores for both the test group and the vehicle control were 1.0 48 hours after the last treatment. In all four studies, the vehicles and positive controls induced the appropriate responses.  


Justification for classification or non-classification

2,2,4-Trimethyl-1,3-pentanediol is not currently classified for Skin Sensitization according to Annex I of Directive 67/548/EEC.  Based on a weight-of-the-evidence assessment, 2,2,4-trimethyl-1,3-pentanediol is not classified for Skin Sensitization according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 and UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS).