Dimethyl naphthalene-2,6-dicarboxylate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March to May 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

Method conducted prior to enactment of REACH Regulation.

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl naphthalene-2,6-dicarboxylate

EC Number:

212-661-4

EC Name:

Dimethyl naphthalene-2,6-dicarboxylate

Cas Number:

840-65-3

Molecular formula:

C14H12O4

IUPAC Name:

2,6-dimethyl naphthalene-2,6-dicarboxylate

Test material form:

solid: flakes

Details on test material:

CAS number: 840-65-3

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Limited, Darley Oaks, Newchurch, Burton-on-Trent, Staffordshire
- Age at study initiation: young adult (less than one year old)
- Weight at study initiation: within the weight range 300-342g
- Housing: The animals were multiply housed in aluminium cages (dimensions 48 x 61 x 25 cm) with a grid floor. Beneath each cage was a suspended tray lined with absorbent paper.
- Diet (e.g. ad libitum): Guinea Pig Diet FD1, supplied by Special Diets Services Ltd, I Stepfield, Witham, Essex, CM8 3AD was available ad libitum
- Water (e.g. ad libitum): The animals had access to domestic, mains quality drinking water ad libitum.
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Mean environmental maximum and minimum temperatures were 20°C and 19°C.
- Humidity (%): 38%
- Air changes (per hr): 15-20 air changes per hour
- Photoperiod (hrs dark / hrs light): There was automatic control of light cycle; light hours were 0700-1900 hours.

No additional data

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Induction 2

Concentration / amount:

75% Dimethyl-2,6-naphthalene dicarboxylate

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Challenge 2

Concentration / amount:

75% Dimethyl-2,6-naphthalene dicarboxylate

No. of animals per dose:

Control Group: 10
Test Group: 20

Details on study design:

RANGE FINDING TESTS: Dose ranging for induction and challenge were conducted via topical application of formulations of Dimethyl-2,6-naphthalene dicarboxylate.
On the day prior to administration, hair was clipped from an area (4 cm x 6 cm) on both flanks of the animals.
The dose level is 0.5, 1, 2, 5, 10, 25, 50 and 75% Dimethyl-2,6-naphthalene dicarboxylate.
Each patch was covered with aluminium foil and then with Blenderm occlusive tape and elastic bandage wrapped round the torso of the animal.
The patches were removed after 6 h.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 6 h
- Test groups: 30 animals
- Control group: 10 animals
- Site: left flank under a Webril
- Frequency of applications: once each week
- Duration: for 3 consecutive weeks
- Concentrations: 0.5 mL 75% Dimethyl-2,6-naphthalene dicarboxylate

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: thirteen days after the final induction application
- Exposure period: 6
- Test groups: 30 animals
- Control group: 10 animals
- Site: right flank
- Concentrations: 75% Dimethyl-2,6-naphthalene dicarboxylate
- Evaluation (hr after challenge): The challenges sites were evaluated 24 and 48 hours after removal of the patches.

No additional data

Challenge controls:

The control animals were challenged using the same procedure for test animals.

Positive control substance(s):

yes

Remarks:

Hexylcinnamaldehyde (HCA)

Results and discussion

Positive control results:

Following challenge at a dose level of 50% HCA in acetone/PEG 400 (70:30 v/v), 60% of the Test Group animals showed a positive response. No positive responses were noted in the Control Group animals. These results demonstrate the ability of the methodology to identify a mild/moderate sensitiser.

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

75%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 75%. No with. + reactions: 0.0. Total no. in groups: 20.0.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

75%

No. with + reactions:

0

Total no. in group:

20

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 75%. No with. + reactions: 0.0. Total no. in groups: 20.0.

Any other information on results incl. tables

Dose Ranging for Induction and Challenge

No reactions were noted at any test site treated with dose levels up to 75% Dimethyl-2,6-naphthalene dicarboxylate.

Body Weight

Body weight performance was considered to have been satisfactory.

Clinical Signs

One animal was hunched, thin and salivating prior to the first induction application, and was humanely killed.

In the surviving animals, no clinical signs, other than skin reactions at the test sites, were noted.

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In an OECD 406 skin sensitisation study, conducted according to GLP, NDC is considered not to be a sensitiser in guinea pigs.