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EC number: 686-241-8 | CAS number: 81058-27-7
In a Local Lymph Node Assay (LLNA) in mice (CBA/J) according to OECD Guideline 429 and EU Method B.42, the substance T003421 was not considered a skin sensitiser (Latour, 2017).
In a key LLNA study (Latour, 2017), three experimental groups of five female CBA/J mice were treated with test item concentrations of 2, 25 or 50% w/w for three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (Acetone/Olive oil (4:1 v/v)).
Three days after the last exposure, all animals were injected with3H-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.
No erythema of the ears was observed in any of the animals examined. White test item remnants were present on the dorsal surface of the ears throughout all dosing groups (Days 1-3) which did not hamper scoring of the skin reactions.
No mortality occured and no clinical signes of systemic toxicity were observed in the animals of the main study. No macroscopic abnormalities of the surrounding area were noted for any of the animals. Body weights and body weight gain of experimental animals remained in the same range as controls over the study period.
Mean DPM/animal values for the experimental groups treated with test item concentrations 2, 25 and 50% were 799, 691 and 748 DPM, respectively. The mean DPM/animal value for the vehicle control group was 740 DPM. The SI values calculated for the item concentrations 2, 25 and 50% were 1.1, 0.9 and 1.0, respectively.
Since there was no indication that the test item elicited a SI ≥ 3 when tested up to 50%, T003421 was not considered to be a skin sensitizer.
Based on these results, T003421 was not regarded as a skin sensitizer according to the recommendations made in the test guidelines.
In a second supporting (non-GLP) LLNA study, Moore (2012) investigated the skin sensitisation potential of T003421 following topical (epidermal) application to the dorsal surface of each ear lobe (left and right) with different test item concentrations of 10, 25 and 50% (w/v) in acetone:olive oil (4:1).
Preliminary investigations were performed at 25 and 50% w/v with 2 female mice perconcentration to establish the highest concentration of test substance which did not lead to systemic toxicity or excessive local irritation.
The main phase of the study comprised three treated groups, each comprising four female mice receiving T003421 at concentrations of 10, 25 or 50% w/v.
Similarly constituted groups received the vehicle (acetone:olive oil (4:1 w/v)) or positive control substance (25% v/v hexyl cinnamic aldehyde). The mice were treated by daily application of 25ml of the appropriate concentration or control (vehicle or positive), to the dorsal surface of both ears for three consecutive days.
The SI obtained for 10, 25 and 50% w/v were 1.1, 1.1 and 1.2, respectively, which indicated that the test item did not show the potential to induce skin sensitization.
The EC3 value was considered to be greater than the highest concentration tested (50% w/v). The SI for the positive control substance hexyl cinnamic aldehyde was 7.6. T003421 was not regarded as a potential skin sensitizer.
Based on two LLNA studies in female mice (Latour 2016 and Moore 2012), the test item does not have to be classified for skin sensitization according to EU CLP.
No data were available to decide on the classification for respiratory sensitisation.
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