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Diss Factsheets

Administrative data

Description of key information

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well reported study performed under GLP and using a standard test method.
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
Pre-test bodyweights 267-356g (males), 246-352g (females).
Route:
intradermal and epicutaneous
Vehicle:
water
Concentration / amount:
Intradermal induction: 1% in water (mixed 1:1 with FCA at one of the 3 injection sites) - determined to be non-necrotic in preliminary testing.
Topical induction: 75% in water - determined to be systemically tolerated and produce no more than mild/moderate irritation in preliminary testing.
Challenge: 25% in water - selected as the highest, non-irritant concentration from preliminary testing.
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
Intradermal induction: 1% in water (mixed 1:1 with FCA at one of the 3 injection sites) - determined to be non-necrotic in preliminary testing.
Topical induction: 75% in water - determined to be systemically tolerated and produce no more than mild/moderate irritation in preliminary testing.
Challenge: 25% in water - selected as the highest, non-irritant concentration from preliminary testing.
No. of animals per dose:
Test group:10 males, 10 females.
Vehicle control group: 5 males, 5 females.
Details on study design:
Preliminary test:
- 3 animals dosed intradermally at 1, 10, 25 and 50%
- 6 animals dosed topically at 10, 25, 50, 75% (0.1 ml, 24h under occlusive patch).
Main test:
- 6 intradermal injections/animal. 2x 0.1 ml FCA, 2x 0.1 ml test solution or water(controls), 2x 50% FCA/test solution or 50% FCA/water(controls)
- 7 days later, 0.2 ml test solution or water(controls) applied topically between injection sites (48h under occlusive patch)
- 14 days later, topical application of 0.2 ml test solution (site 1) and water (site 2) to test and control animals (24h under occlusive patch).
Challenge controls:
Test solution and water applied to all animals.
Positive control substance(s):
yes
Remarks:
2-mercaptobenzothiazole: study performed 3 months earlier in the same laboratory and using the same test methods.
Positive control results:
2-mercaptobenzothiazole, animals induced by intradermal injection (5%) and topical application (50%), then challenged (25%): 5/10 males and 3/5 females showed positive challenge reactions. Vehicle (acetone) control group: 2/10 showed positive challenge reactions.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
25%
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: 25%. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
25%
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: 25%. No with. + reactions: 0.0. Total no. in groups: 20.0.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
Water only
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: Water only. No with. + reactions: 0.0. Total no. in groups: 10.0.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
Water only
No. with + reactions:
0
Total no. in group:
10
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: Water only. No with. + reactions: 0.0. Total no. in groups: 10.0.

Local reactions to induction treatments in the test group (scores of 1 or 2 after intradermal injection, 0, 1 or 2 after topical application) indicated that the selected concentrations were appropriate.

Local reactions to topical application in the preliminary test (2/6 animals showing score 1 at 25%, 1/6 showing score 2 at 50%) indicated that the selected challenge concentration was appropriate.

No test group animal showed skin reactions to water application at challenge.

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Based on the complete absence of reactions to challenge in this study, the test substance has no demonstrated potential to cause delayed contact sensitisation of the skin.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Based on a GLP study and several supporting studies including human patch tests, the overall conclusion is that the substance possesses no sufficient sensitizing power to merit formal classification.


Migrated from Short description of key information:
The study designated as most reliable (Klimisch 1), a Guinea pig maximisation test (GPMT), reported wholly negative results. Another GPMT study, following a similar test procedure but non-GLP, used a higher challenge concentration (50% rather than 25%) and found 30% of test animals showing evidence of sensitisation. Two other Guinea pig sensitisation studies using different test protocols showed no or less than 30% response. The GPMT is an accepted test for hazard identification of skin sensitising substances. It has been regarded as a more sensitive assay that may also, for certain substances, overestimate the sensitisation hazard for the substance tested. This is partially compensated for by the fact that a positive reaction in at least 30 % of the animals is required for classifying the test substance as sensitiser.

Also taken into account is that human patch testing of the registered substance found no contact sensitising activity, and even large-scale patch testing of patients referred for allergy testing has identified only a minor incidence (< 5% ) of sensitised individuals.

Justification for selection of skin sensitisation endpoint:
Concerns a reliable Guinea pig maximisation study reporting no evidence of sensitising activity, supported by other studies indicating no or only a weak sensitising activity. In no case the results show that the substance is of sufficient sensitizing power to merit formal classification.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the overall conclusion for contact sensitisation, the test substance possesses no sufficient sensitizing power to merit formal classification.