Registration Dossier

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Additional information:

2-Methylbutyraldehyde (2-methylbutanal is assessed to be sensitizing based on the common terminal carbonyl group of aldehydes. This reactive group gives reason for a structural alert. Carbonyl groups may form Schiff bases, which then can lead to an immune response. The observation, that many of the tested aliphatic aldehydes were found to be weak or moderate sensitizers, provide evidence for this concept.


The waiving argument is supported by results of a local lymph node assay (Dow 2008) demonstrating a weak sensitizing response of 2-methylbutyraldehyde.


Dow 2008


In a local lymph node assay with 2-methylbutyraldehyde (purity 98.2%), adult female CBA/J mice (6 animals per group) were tested using concentrations of 5, 25, and 100% test substance in vehicle (4:1 acetone/olive oil). Hexyl cinnamic aldehyde (30% in vehicle) was used as positive control material.


There was no effect of treatment on body weight development. Skin irritation, which resolved in all mice by day 6, was only observed on day 3 in mice dosed with 100% test substance (slight to well-defined erythema, 4 and 2 of 6 mice respectively). Increases in lymph cells were only observed in the 100% test group. For this group a SI of 4.4 was determined. EC3 was 70%.


In this study, 2-methylbutyraldehyde is a weak dermal sensitizer (categorized according to the expert ECETOC panel - Technical Report No. 87, 2003) (Dow 2008).


This study is classified as acceptable. It was performed according to OECD test guideline 429 with some restrictions (no individual caging, test substance concentrations were not in consecutive order).

Migrated from Short description of key information:
2-Methylbutyraldehyde is assumed to be skin sensitizing using data waiving (Annex XI, Sect 1.5) based on a grouping of substances and read-across approach.
This waiving argument is supported by results of a local lymph node assay resulting in a weak sensitizing response of 2-methylbutyraldehyde.

Justification for classification or non-classification