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EC number: 248-654-8
CAS number: 27776-01-8
Relative size lymph nodes, radioactivity counts (DPM) and Stimulation
Mean DPM ± SEM(4)
1 TS = test substance (% w/w).
2. Relative size auricular lymph nodes (-, -- or ---: degree of
reduction, +,++ or +++: degree of enlargement, n: considered to be
3. DPM = Disintegrations per minute
4. SEM = Standard Error of the Mean
A study was performed to assess the Contact Hypersensitivity to
Phenyl-tolyl-ethane in the Mouse (Local Lymph Node Assay). The study was
carried out based on the guideline OECD, Section 4, Health Effects,
Test substance concentrations selected for the main study were based on
the results of a pre-screen test. The two animals treated at 100% were
found dead or sacrificed for humane reasons on Day 2. The two animals
treated at 50% showed signs of systemic toxicity (hunched posture). It
was concluded that these concentrations could not be tolerated well and
did not comply with the selection criteria, and therefore the highest
test substance concentration selected for the main study was a 25%
concentration. In the main study, three experimental groups of five
female CBA/J mice were treated with test substance 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
vehicle alone (Acetone/Olive oil (4:1 v/v)). 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. The slight irritation
of the ears as shown by the animals treated at 25% was considered not to
have a toxicologically significant effect on the activity of the nodes.
No irritation of the ears was observed in any of the animals treated
with vehicle or at test substance concentration of 10% or 5%. 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 the experimental animals remained in the same range as controls
over the study period, except for the slight body weight loss noted in
two animals treated at 25% and one at 5%. This body weight loss was
considered not toxicologically significant. The auricular lymph nodes of
the animals of the experimental and control groups were considered
normal in size, except for the enlarged nodes found in two animals
treated at 25%. No macroscopic abnormalities of the surrounding area
were noted in any of the animals. Mean DPM/animal values for the
experimental groups treated with test substance concentrations 5, 10 and
25% were 139, 98 and 132 DPM respectively. The mean DPM/animal value for
the vehicle control group was 97 DPM. The SI values calculated for the
substance concentrations 5, 10 and 25% were 1.4, 1.0 and 1.4
respectively. Since there was no indication that the test substance
elicits an SI ≥ 3 when tested up to the highest tolerable concentration
of 25%, Phenyl-tolyl-ethane was considered not to be a skin sensitizer.
It was established that the EC3 value (the estimated test substance
concentration that will give a SI =3) (if any) exceeds 25%. Based on
these results, Phenyl-tolyl-ethane would not be regarded as a skin
sensitizer according to the recommendations made in the test guidelines.
Members of the diphenylmethane category did not show any skin
sensitising properties. There is no information available for
respiratory sensitisation. Therefore, there is a data gap in this
respect. However, the data gap cannot be fulfilled with experimental
data, since there is no internationally accepted animal model for
respiratory sensitisation. For skin sensitisation, there is no reason to
believe that results obtained in experimental animals would not be
applicable to humans.
No further testing is required. The available data is adequate for risk
assessment and classification and labelling purposes.
detailed read across rationale and justification within the
diphenylmethane category see section 13, Read across document.
Benzyltoluene is not classified as skin sensitiser.
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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