Registration Dossier

Administrative data

Description of key information

Skin response to challenge is qualitatively and quantitatively indistinguishable from skin response to initial induction, or to skin response in a naive control, and as such is not an indication for sensitization.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)

Justification for classification or non-classification

The contact dermal sensitization potential of lactic acid was investigated using a modified Buehler Closed Patch Test. No mortalities occurred and all animals gained body weight. The test article (100%) produced very slight erythema at 3 sites and very slight oedema at 1 site after the 1st induction. Erythema grades increased in severity after the 2nd induction application. One site was graded as severe erythema, however, this grade was given a 4 due to pinpoint pitting of the skin and scab formation, not for redness. Due to the increase of severity of the reactions, the concentration of the test article for induction was reduced to 30% and the induction site was changed to the left flank. Very slight erythema was noted after the 5th induction application. Grades ranging from very slight to severe erythema were noted from the 7th to the 9th induction applications. Again, the severe (grade 4) reactions were given this grade due to pinpoint pitting of the skin and the eschar formation, not for redness.

After the challenge application, the test article (100%) produced grade 4 erythema in up to 6 test animals. These gradings were very similar in character as those seen during the induction applications, that is, pinpoint pitting of the skin and eschar formation, very little redness. These reactions were considered to be irritation reactions, not sensitization reactions. Other reactions noted at challenge for the test animals were very slight to moderate erythema, and very slight to moderate oedema. The test article (100%) produced grade 4 erythema in up to 8 naive control animals. These gradings were also pinpoint pitting of skin and eschar formation with very little redness. These reactions were considered to be irritation reactions, not sensitization reactions. Other reactions noted for the naive control animals were very slight to moderate erythema and very slight to moderate oedema. The reactions seen in the naive control animals at the challenge application were similar to the reactions seen for the test group animals and lactic acid was not considered to be a contact dermal sensitizer.