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Diss Factsheets

Administrative data

Description of key information

Skin sensitisation, in vivo (similar OECD 406): not sensitising

Read-across from analogue source substance bis(isopropyl)naphthalene (CAS No. 38640-62-9)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Refer to the analogue approach justification provided in IUCLID section 13
Reason / purpose for cross-reference:
read-across source
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
15% TS in vehicle
No. with + reactions:
17
Total no. in group:
20
Clinical observations:
no findings reported grading score (mean): 0.58
Remarks on result:
other: Source: CAS No. 38640-62-9, Sterner, 1986
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
15% TS in vehicle
No. with + reactions:
7
Total no. in group:
20
Clinical observations:
no findings reported grading score (mean): 0.23
Remarks on result:
other: Source: CAS No. 38640-62-9, Sterner, 1986
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
15% TS in vehicle
No. with + reactions:
18
Total no. in group:
20
Clinical observations:
no findings reported grading score (mean): 1.13
Remarks on result:
other: Source: CAS No. 38640-62-9, Sterner, 1986
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
15% TS in vehicle
No. with + reactions:
20
Total no. in group:
20
Clinical observations:
no findings reported grading score (mean): 0.75
Remarks on result:
other: Source: CAS No. 38640-62-9, Sterner, 1986
Group:
positive control
Remarks on result:
other: no information given in study report
Interpretation of results:
other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008
Conclusions:
In a guinea pig maximisation test (GPMT), no skin sensitisation was observed following occlusive epicutaneous challenge after induction treatments (intradermal injection and occlusive epicutaneous exposure).
Executive summary:

The skin sensitisation potential of the target substance is predicted based on an adequate and reliable in vivo study of a structural analogue source substance. In a guinea pig maximisation test (GPMT) , no skin sensitisation was observed following occlusive epicutaneous challenge after induction treatments (intracutaneous injection and occlusive epicutaneous exposure). As explained in the analogue justification, the differences in molecular structure between the target and the source substances are unlikely to lead to differences in the skin sensitisation potential.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

No data on skin sensitisation with 2,6-diisopropylnaphthalene (CAS 24157-81-1) are available. This endpoint, therefore, is assessed by means of read-across from the analogue source substance bis(isopropyl)naphthalene (CAS 38640-62-9).

In a valid guinea pig maximisation test similar to OECD guideline 406 under GLP conditions, Pirbright white guinea pigs (20/group) were induced with a single intradermal injection of bis(isopropyl)naphthalene (CAS No. 38640-62-9) at 10% (in water, containing the emulsifier Cremophor) using the adjuvant complete Freund and an epicutaneous application of the test substance at 10% (in water, containing the emulsifier Cremophor) on the injection site. Epicutaneous challenge exposure was conducted 20 days after the first induction for 24 h under occlusive conditions. 15% of the test substance was applied on the flank of the animals. Evaluation of skin reactions was carried out 24 and 48 h after challenge. No information on positive controls was given in the study report. The test group, as well as the negative control group, showed erythema after 24 and 48 h, with scores ranging predominantly from 0.5 (slight, irregular erythema) to 1 (slight, continuous erythema) and 2 (moderate erythema). There was no significant difference between the test and control groups. In conclusion, in this guinea pig maximisation test slight to moderate erythema were induced after challenge exposure in control as well as in test group animals. The test substance, therefore, did not induce skin sensitisation.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The available data on skin sensitisation for the analogue source substance bis(isopropyl)naphthalene (CAS No. 38640-62-9) do not meet the criteria for classification according to Regulation (EC) No. 1272/2008 (CLP). Data are, therefore, conclusive but not sufficient for classification. Based on an analogue read-across approach, the target substance 2,6-diisopropylnaphthalene (CAS No. 24157-81-1) also does not warrant classification for skin sensitisation.