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EC number: 213-234-5
CAS number: 931-36-2
The test substance was found to be a skin sensitizer in the Local Lymph
- Viability / Mortality: No deaths occurred
during the study period.
- Body Weights: The body weight of the
animals, recorded prior to the first application and prior to treatment
with 3HTdR, was within the range commonly recorded for animals of this
strain and age.
- Lymph Node Weights and Cell Counts: The
measured lymph node weights and –cell counts of all animals treated were
recorded after sacrifice. A statistically significant and biologically
relevant increase in lymph node weight and –cell count was obtained in
the high dose group in comparison to the vehicle control group
(p<0.001). For BALB/c mice, a cutoff-value for the lymph node cell count
index of 1.55 was reported for a positive response. The index determined
for the high dose group exceeded this threshold (index of 2.79).
- Ear Weights: The measured ear weights of
all animals treated were recorded after sacrifice. A statistically
significant increase in ear weights was observed in the high dose group
in comparison to the vehicle control group (p=0.006). For BALB/c mice, a
cutoff-value of 1.1 for the ear weight index was reported for a positive
response regarding ear skin irritation. None of the indices determined
for the test item treated groups exceeded this threshold. Furthermore,
the threshold value of 25% increase in ear weights for excessive local
skin irritation mentioned in OECD guideline 429 was not exceeded in any
Lymph Node Weights
Test item concentration (%)
Lymph node weight (mg)
Index = mean lymph node weight of test
item group related to vehicle group
* statistically significant increase
vs. control group (p < 0.001)
Lymph Node Cell Counts
Lymph node cell count (x10E6)
Index = mean lymph node cell count of
test item group related to vehicle group
Ear weight (mg)
Index = mean ear weight of test item
group related to vehicle group
In a GLP
compliant Local Lymph Node Assay, tested according to OECD guideline
429, 5 female CBA mice per dose were treated daily with the test item at
concentrations of 5, 10, and 25% in acetone:olive oil (4 +1 v/v) by
topical application to the dorsum of each ear lobe for three consecutive
days. 25% was the highest concentration that could be applied whilst
avoiding systemic toxicity and excessive local skin irritation (as
determined by two pre-experiments). A control group of five mice was
treated with the vehicle only. Five days after the first topical
application the mice were injected intravenously into a tail vein with
radio labeled thymidine (³H-methyl thymidine). Approximately five hours
thereafter the mice were sacrificed and the draining auricular lymph
nodes were excised and pooled per animal.
The proliferative capacity of
pooled lymph node cells was determined by the incorporation of ³H-methyl
thymidine. Stimulation Indices of 1.16, 1.49 and 6.83 were determined
with the test item at concentrations of 5, 10, and 25%, respectively and
a EC3 value of 14.2 (w/w) was calculated. Based on the described study
and under the conditions reported, it is concluded that 2-ethyl-4-methylimidazoleis
Based on the findings
in the skin sensitisation study, the substance needs to be classified
with Skin sens
1B, H317 according
to the EU Classification, Labelling and Packaging of Substances and
Mixtures (CLP) Regulation (EC) No. 1272/2008.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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