Phosphoric acid, mono- and di-C16-20-(even numbered, branched and linear)-alkyl esters

Endpoint summary

Description of key information

Based on the EC3 value identified in the LLNA, the test substance is considered to be a moderate skin sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

A study was conducted to determine the skin sensitisation potential of the test substance according to OECD Guideline 429, EU Method B42 and US EPA OPPTS 870.2600 (LLNA), in compliance with GLP. The test substance concentrations selected for the main study were based on the results of a pre-screen test. In the main study, three experimental groups of five female CBA/J mice were treated with test substances concentrations of 5, 10 or 25% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with the vehicle alone (Acetone/Olive oil (4:1 v/v)). A positive control group (alpha-hexylcinnamaldehyde) was also included in the experiment. Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of disintegrations per minute (DPM) and a stimulation index (SI) was subsequently calculated for each group. Mortality/viability, body weights, clinical signs, and irritation (and other local effects) were recorded as well. No erythema was observed in any of the animals, scaliness was noted for all animals treated at 25% and some animals treated at 10% between Days 4 and 6. The majority of auricular lymph nodes were considered normal in size, except for one node in one animal treated at 25%, which was considered enlarged. No macroscopic abnormalities of the surrounding area were noted for any of the animals. Mean DPM/animal values for the experimental groups treated with test substance concentrations 5, 10 and 25% were 644, 1406 and 2811 DPM, respectively. The mean DPM/animal value for the vehicle control group was 460 DPM. The SI values calculated for the test substance concentrations 5, 10 and 25% were 1.4, 3.1 and 6.1, respectively. These results indicate that the test substance could elicit a SI ≥ 3. The data showed a dose-response and an EC3 value (the estimated test substance concentration that will give a SI =3) of 9.7% was calculated. No mortality occurred and no clinical signs of systemic toxicity were observed in the animals of the main study. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period. Under the study conditions and based on the EC3 value, the test substance was considered to be a moderate skin sensitizer (van Sas, 2017).

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of a local lymph node assay, the substance is considered to be moderately sensitizing, with a classification of Skin Sens. 1B - H317: May cause an allergic skin reaction according to the CLP (Regulation 1272/2008/EC) criteria.