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Description of key information

Skin sensitization

The N-methyl p-aminophenol sulphate (55-55-0) was considered to be sensitizing in mice by LLNA method.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
Data from peer-reviewed journal
Reference:
Composition 0
Composition 0
Qualifier:
equivalent or similar to
Guideline:
other: As mentioned below
Principles of method if other than guideline:
Skin sensitization study of N-methyl-p-aminophenol sulphate was performed in mouse by LLNA method
GLP compliance:
not specified
Type of study:
mouse local lymphnode assay (LLNA)
Test material information:
Composition 1
Specific details on test material used for the study:
- Name of test material: p-Methylaminophenol sulfate- IUPAC name: Bis(4-hydroxy-N-methylanilinium) sulphate- Molecular formula: C14H20N2O6S- Molecular weight: 344.386 g/mole- Smiles:CNc1ccc(cc1)O.CNc1ccc(cc1)O.OS(=O)(=O)O- Inchl: 1S/2C7H9NO.H2O4S/c2*1-8-6-2-4-7(9)5-3-6;1-5(2,3)4/h2*2-5,8-9H,1H3;(H2,1,2,3,4)- Substance type: Organic- Physical state: Solid crystalline (off white - white)
Species:
mouse
Strain:
CBA/Ca
Sex:
male/female
Details on test animals and environmental conditions:
Details on test animalTEST ANIMALS- Source: No data available- Age at study initiation:8-12 weeks - Weight at study initiation: No data available- Housing: No data available- Diet (e.g. ad libitum): No data available- Water (e.g. ad libitum): No data available- Acclimation period: No data availableENVIRONMENTAL CONDITIONS- Temperature (°C): No data available- Humidity (%):No data available- Air changes (per hr): No data available- Photoperiod (hrs dark / hrs light): No data available
Vehicle:
dimethylformamide
Concentration:
0.5, 1, 2.5, %
No. of animals per dose:
Total:160.5%: 41% : 42.5%: 4Vehicle control:4
Details on study design:
Details on study designPRE-SCREEN TESTS:- Compound solubility: Test material soluble in DMF- Irritation: No data available- Systemic toxicity:- Ear thickness measurements: 4-5 days after the first application, all mice injected intravenously through the tail vein with 250 μl of phosphate buffered saline (PBS) containing 20 μCi of tritiated thymidine (³H-TdR). After approximately 5 hours, they were killed by CO2 asphyxiation and the auricular lymph nodes excised. The nodes from each group were pooled, a suspension of auricular lymph node cells prepared, and proliferation of these cells measured using β-scintillation counting. The results were used to calculate the Stimulation Index (SI) for proliferation. The EC3 value (the theoretical concentration resulting in an SI value of 3) was subsequently determined.- Erythema scores: No data available MAIN STUDYANIMAL ASSIGNMENT AND TREATMENT- Name of test method: LLNA- Criteria used to consider a positive response: A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a threefold or greater increase in HTdR incorporation compared with control value.TREATMENT PREPARATION AND ADMINISTRATION: The dose volume of 25 μl was applied to the dorsal surface of both ears at concentrations of 0.5%, 1%, 2.5% once daily for 3 consecutive days. Control animals received Vehicle alone.
Positive control substance(s):
not specified
Statistics:
No data available
Positive control results:
No data available
Parameter:
SI
Value:
2.5
Test group / Remarks:
0.5% test group
Remarks on result:
other: positive effect was observed
Parameter:
SI
Value:
3.4
Test group / Remarks:
1% test group
Remarks on result:
other: positive effect was observed
Parameter:
SI
Value:
6.7
Test group / Remarks:
2.5% test group
Remarks on result:
other: positive effect was observed
Cellular proliferation data / Observations:
The ratio of test to control lymphocyte proliferation (T/C) was determined as 2.5, 3.4 and 6.7 indcated positive effect for skin sensitization.
Interpretation of results:
other: sensitizing
Conclusions:
The N-methyl p-aminophenol sulphate (55-55-0) was considered to be sensitizing in mice by LLNA method
Executive summary:

The skin sensitization studyN-methyl p-aminophenol sulphate(55-55-0)was performed on 16CBA/Ca male or female mice of age 8-12 weeks .The test material soluble in DMF.The dose volume of 25 μl was applied to the dorsal surface of both ears at concentrations of 0.5%, 1%, and 2.5% once daily for 3 consecutive days. Control animals received Vehicle alone.4-5 days after the first application, all mice injected intravenously through the tail vein with 250 μl of phosphate buffered saline (PBS) containing 20 μCi of tritiated thymidine (³H-TdR). After approximately 5 hours, they were killed by CO2 asphyxiation and the auricular lymph nodes excised. The nodes from each group were pooled, a suspension of auricular lymph node cells prepared, and proliferation of these cells measured using β-scintillation counting. The results were used to calculate the Stimulation Index (SI) for proliferation. The EC3 value (the theoretical concentration resulting in an SI value of 3) was subsequently determined.A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a threefold or greater increase in HTdR incorporation compared with control value. The ratio of test to control lymphocyte proliferation (T/C) was determined as 2.5, 3.4 and 6.7 HenceN-methyl p-aminophenol sulphate(55-55-0) was considered to be sensitizing in mice by LLNA method.

 

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Skin Sensitization

In different studies, N-methyl p-aminophenol sulphate (55-55-0) has been investigated for potential of skin sensitization to a greater or lesser extent. The studies are based on in vivo experiments in guinea pig and human for target chemical N-methyl p-aminophenol sulphate (55-55-0).

 The experimental study conducted by D.A. Basketter and E.W. Scholes (Fd. Chem. Toxic .Vol. 30, No 1, pp.65-69,1992).The skin sensitization study N-methyl p-aminophenol sulphate(55-55-0)was performed on 16CBA/Ca male or female mice of age 8-12 weeks .The test material soluble in DMF. The dose volume of 25 μl was applied to the dorsal surface of both ears at concentrations of 0.5%, 1%, and 2.5% once daily for 3 consecutive days. Control animals received Vehicle alone.4-5 days after the first application, all mice injected intravenously through the tail vein with 250 μl of phosphate buffered saline (PBS) containing 20 μCi of tritiated thymidine (³H-TdR). After approximately 5 hours, they were killed by CO2 asphyxiation and the auricular lymph nodes excised. The nodes from each group were pooled, a suspension of auricular lymph node cells prepared, and proliferation of these cells measured using β-scintillation counting. The results were used to calculate the Stimulation Index (SI) for proliferation. The EC3 value (the theoretical concentration resulting in an SI value of 3) was subsequently determined. A chemical was regarded as a sensitizer in the LLNA if at least one concentration of the chemical resulted in a threefold or greater increase in HTdR incorporation compared with control value. The ratio of test to control lymphocyte proliferation (T/C) was determined as 2.5, 3.4 and 6.7 Hence N-methyl p-aminophenol sulphate(55-55-0) was considered to be sensitizing in mice by LLNA method.

 Also these results are further supported by the experimental study conducted by D.A. Basketter and E.W. Scholes (Fd. Chem. Toxic .Vol. 30, No 1, pp.65-69,1992) The skin sensitization study of N-methyl-p-aminophenol sulphate(55-55-0)was performed by Guinea pig maximisation test. Albino Dunkin Hartley G.pigs weighting approximately 350g were used. Preliminary irritation tests were carried out to determine the concentration of the test material suitable for induction and challenge of sensitization. In induction phase, induction given using 0.5%, concentration in Acetone – polyethylene glycol 400 (70:30, v/v) by intradermal route for 6 times on shoulder region. After 6-8 days epicutaneous application was carried out using 25% concentration in same vehicle applied on same site for 48hr as occluded patch. In challenge phase,10-14 days latter test substance in 5 % concentration in same vehicle was applied as occlusive patch on one flank for 24 hr. Challenge site were scored for erythema (Scale 0-3) and oedema 24 and 48 hr after removal of the patch. 90% animals were observed positive for skin sensitizing reaction after challenge application. Hence the N-methyl-p-aminophenol sulphate(55-55-0)was considered to be skin sensitizing in guinea pig.

 Also these results are further supported by the experimental study conducted by Akiko Ito , Kazue Nishioka et.al. (Contact Dermatitis, 77, 42–48, 2017) The skin sensitization study of N-methyl-p-aminophenol sulphate (55-55-0) was performed in human. The 195 patients were investigated for suspected allergic contact dermatitis caused by hair dyes or perming solution scontains test material. The patients was 58 years (interquartile range 12)and>50% of them were in their fifties or sixties .the test material in 0.5% and 1% concentration in petrolatum was applied as patch for 2 days exposure by using Finn Chambers®(Smart Practice, Phoenix, AZ,USA) on Scampor®tape (Alpharma, Vennesla, Norway).Readings were performed on day (D) 2, D3 and D7 after application,41 patients were positive for skin sensitization from total 195 tested i.e 21% Hence N-methyl-p-aminophenol sulphate(55-55-0)was considered to be skin sensitizing in human.

 

Also these results are further supported by the experimental study conducted by Carola Liden (Contact Dermatitis 1984:10:77-87) The skin sensitization study of N-methyl-p-aminophenol sulphate(55-55-0) was performed in human. The 23 subjects in treated group and 200 subjects in control group were investigated. In induction phase the test material in 5% in petrolatum was applied as patch for 48hr exposure by using Finn-Chamber (Epi-test, Finland)while 2-3 weeks later challenge application 1% concentration in liquid was applied as Scanpor surgical tap (Norge-plaster, Norway) for 48hr and evaluated after 72hr for skin reaction.6 were positive for skin sensitization from total 23 tested in treated group while 1 subject from control group indicated positive skin sensitization .Hence N-methyl-p-aminophenol sulphate(55-55-0)was considered to be skin sensitizing in human.

Also these results are further supported by the experimental study conducted by European Commission (Scientific Committee On Consumer Products, SCCP/0963/05, 2006) The skin sensitization study N-methyl p-aminophenol sulphate(55-55-0)was performed on 28CBA/J female mice using OECD 429 guideline. The test material soluble in dimethysulfoxide (DMSO).This vehicle was selected on the basis of the results from a previous solubility study showing that N-methyl p-aminophenol sulphate was non-soluble in other recommended vehicles, and that 5% N-methyl-p-aminophenol in DMSO was the maximal practicable concentration and this concentration was non-irritating in a preliminary test performed in 4 female mice While 25% (v/v) α hexylcinnamaldehyde (HCA) in DMSO used as positive control. The dose volume of 25 μl was applied to the dorsal surface of both ears at concentrations of 0.25%, 0.5%, 1%, 2.5% and 5% once daily for 3 days designated as days 1, 2 and 3. Vehicle control animals received DMSO, while positive control animals received 25% (v/v) α hexylcinnamaldehyde (HCA) in DMSO.At least once daily all the animals were observed for mortality/morbidity and clinical signs. Body weights were recorded on day 1 and on the day of sacrifice (day 6). On days 1, 2, 3 and 6, the thickness of the left ear was measured and any irritation reactions recorded to assess any possible irritant effect of the test item. Ear thickness was not measured in the positive control group. On day 6, all animals were administered 250 μl of 0.9% NaCl containing 20 μCi of tritiated thymidine (³H-TdR). After approximately 5 hours, they were killed and the auricular lymph nodes excised. The nodes from each group were pooled, a suspension of auricular lymph node cells prepared, and proliferation of these cells measured using β-scintillation counting. The results were used to calculate the Stimulation Index (SI) for proliferation. The EC3 value (the theoretical concentration resulting in an SI value of 3) was subsequently determined. No compound-related cutaneous reactions were observed at any tested concentration. A dose related increase in SI was observed in treated group animals and the threshold positive value of 3 was exceeded at concentrations of 2.5% and 5%. The calculated EC3 value was 2.2%.As test material induced delayed contact hypersensitivity under the conditions of this study. The EC3 value calculated (2.2%) indicates that it should be considered a moderate sensitizer. Hence the N-methyl p-aminophenol sulphate (55-55-0) was considered to be sensitizing in mice by LLNA method.

 Thus based on the above studies on N-methyl p-aminophenol sulphate (55-55-0) in mice , guinea pig and human , it can be concluded N-methyl p-aminophenol sulphate (55-55-0) a skin sensitizer. Thus comparing the above studies with the criteria of CLP regulation, N-methyl p-aminophenol sulphate (55-55-0) can be considered as classified for skin sensitization.

 

 

 

 

 

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Thus comparing the above studies with the criteria of CLP regulation, N-methyl p-aminophenol sulphate (55-55-0) can be considered as classified for skin sensitization.