1-naphthol

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 2001 - August 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

1-naphthol

EC Number:

201-969-4

EC Name:

1-naphthol

Cas Number:

90-15-3

Molecular formula:

C10H8O

IUPAC Name:

naphthalen-1-ol

Test material form:

solid: flakes

Details on test material:

Light cream flakes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Lot I 6694
- Expiration date of the lot/batch: No Data
- Purity test date: No data
- Purity : > 99%.
- Impurity : there was no evidence to suggest the presence of any significant impurities other than 2-Naphthol at 0.09% w/w and Iron at 2.5 ug/g.

RADIOLABELLING INFORMATION (if applicable)
- Specific activity: 3H
- Locations of the label : methyl Thymidine (Amersham TRA 310, aqueous solution, steriliez 74 GBq/mmol)
- Expiration date of radiochemical substance: No data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature (17-20°C) away from direct sunlight
- Stability under test conditions:Yes
- Solubility and stability of the test substance in the solvent/vehicle: Yes
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: No data

TREATMENT OF TEST MATERIAL PRIOR TO TESTING : No

FORM AS APPLIED IN THE TEST Suspension

In vivo test system

Test animals

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles Rivers Deutschland GmBh
- Females nulliparous and non-pregnant: yes
- Microbiological status of animals, when known: No data
- Age at study initiation: 7 - 12 weeks
- Weight at study initiation: 14.6 - 25.4 g
- Housing: unique cage number
- Diet (ad libitum): Pelleted standard Kliba 3433
- Water (ad libitum): tap water from Itingen
- Acclimation period: Yes
- Indication of any skin lesions: only animals without any visible signs of illness were used for the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/-3°C
- Humidity (%): 30-70%
- Air changes (per hr): 10-15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours light / 12 hours dark

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

0.1 ; 0.25 ; 0.5 ; 1 and 2.5%

No. of animals per dose:

3

Details on study design:

PRE-SCREEN TESTS:
- Compound solubility: Yes
- Irritation: No
- Systemic toxicity: No
- Ear thickness measurements: No
- Erythema scores: No

MAIN STUDY
12.5 μl 1-naphthol 0.1, 0.25, 0.5, 1 and 2.5% in 4:1 acetone:olive oil was applied on days 1, 2 and 3 by topical application to the ventral and dorsal surfaces of each ear. Five days after the first topical application, the mice were injected intravenously with 3H-methyl thymidine, five hours later killed and the draining lymph nodes excised and pooled. Single cell suspensions were prepared and the proliferation capacity determined.

ANIMAL ASSIGNMENT AND TREATMENT : No data

TREATMENT PREPARATION AND ADMINISTRATION:
Mice were treated by epidermal topical application to the dorsal surface of each ear lobe (left and right) with different test item concentration. The application volume, 25 µl, was spread over the entire dorsal surface of each ear lobe once daily for three consecutive days.
Five days after the first topical application, the mice were administrated with 250 µl of 87.55 µCi/ml 3HTdR by intravenou injection via a tail vein.
Approximately five hours after treatment with 3HTdR all mice were euthanized by intraperitoneal injection of Narcoren at a dose of at least 2ml/kgbw.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

The mean values and standard deviations were calcultaed in the body weight.

Results and discussion

Positive control results:

The SI for the positive control was 2.4, 3.7, and 7.0 respectively for the 5, 10 and 25% dilutions

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

ca. 1.4

Test group / Remarks:

0.1%

Results 2

Parameter:

SI

Value:

ca. 1

Test group / Remarks:

0.25%

Results 3

Parameter:

SI

Value:

ca. 1.2

Test group / Remarks:

0.5

Results 4

Parameter:

SI

Value:

ca. 1.5

Test group / Remarks:

1%

Results 5

Parameter:

SI

Value:

ca. 8.5

Test group / Remarks:

2.5%

Results 6

Key result

Parameter:

EC3

Value:

1.3

Test group / Remarks:

2.5 %

Cellular proliferation data / Observations:

DETAILS ON STIMULATION INDEX CALCULATION
See table 1 - Stimulation Index

EC3 CALCULATION No data

CLINICAL OBSERVATIONS: No clinical signs occured during the study period.

BODY WEIGHTS The body weight of the animals was within the range commonly recored for animals of this strain and age.

MORTALITY No death occured during the study period.

Any other information on results incl. tables

Table 1 - Stimulation Index

Concentration (% w/v)	Stimulation Index
0.1	1.4
0.25	1.0
0.5	1.2
1.0	1.5
2.5	8.5

Applicant's summary and conclusion

Interpretation of results:

Category 1A (indication of significant skin sensitising potential) based on GHS criteria

Conclusions:

1-Naphthol produced evidence of allergic contact sensitisation in this study at when tested at 2.5%. The EC3 value was calculated to be 1.3. With an EC3 value of 1.3, 1-naphthol is a ‘strong’ sensitizer.

Executive summary:

12.5 μl 1-naphthol 0.1, 0.25, 0.5, 1 and 2.5% in 4:1 acetone:olive oil was applied on days 1, 2 and 3 by topical application to the ventral and dorsal surfaces of each ear. Five days after the first topical application, the mice were injected intravenously with 3H-methyl thymidine, five hours later killed and the draining lymph nodes excised and pooled. Single cell suspensions were prepared and the proliferation capacity determined.

The Mean stimulation indices was 1.4, 1.0, 1.2, 1.5 and 8.5 respectively for 0.1, 0.25, 0.5, 1.0 and 2.5% w/v concentration. The SI for the positive control was 2.4, 3.7, and 7.0 respectively for the 5, 10 and 25% dilutions.

1-Naphthol produced evidence of allergic contact sensitisation in this study at when tested at 2.5%. The EC3 value was calculated by the SCCS (The SCCP adopted this opinion in  April 2008: Opinion on 1 -naphthol SCCP/1123/07) to be 1.3.