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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
Study period:
The study was conducted in 1979.
Reliability:
2 (reliable with restrictions)
Qualifier:
no guideline followed
Principles of method if other than guideline:
Induction: Days 0 – 20.
On Day 0, 0.1 mL of the test material undiluted and at progressively diluted solutions were applied to an area measuring 8 cm2 on the clipped flank skin of six guinea pigs per concentration groups.
The applications were repeated daily for three weeks, or done 5 times weekly during four weeks, always using the same skin site. Te application site was left uncovered. If very strong skin reactions were provoked then the application site was changed.

Challenge: Days 21 to 35.
To determine whether or not contact sensitisation was induced, all groups of guinea pigs previously treated for 21 days, as well as 6 to 8 untreated or only with the vehicle pre-treated controls are tested on Days 21 and 35 on the contralateral flank with the test material at the minimal irritating and some lower concentrations. The minimal irritating concentration of each material is used in order to confirm the biological activity determined before starting the induction (Day -1) and to exclude false results based on instability of the test materials. These tests are performed by applying with a pipette 0.025 mL of each concentration to skin areas measuring 2 cm2, the reactions being read after 24, 48 and / or 72 hours. This procedure enables to determine the minimal sensitising concentration necessary for inducing allergic contact hyper-sensitivity and the minimal eliciting concentration necessary to cause a positive reaction.
The test material is considered allergenic at a concentration when at least one out of the eight animals of this concentration group shows positive reactions with non-irritant concentrations used for challenge, i.d. its threshold concentration causing skin-reactions is shifted to the lower part of the concentration range used for challenge.
GLP compliance:
no
Remarks:
Study pre-dates GLP.
Type of study:
open epicutaneous test
Species:
guinea pig
Strain:
not specified
Sex:
not specified
Details on test animals and environmental conditions:
No data
Route:
epicutaneous, open
Vehicle:
other: Ethanol
Concentration / amount:
3, 10, 30 and 100 %
Route:
epicutaneous, open
Vehicle:
other: Ethanol
Concentration / amount:
3, 10, 30 and 100 %
No. of animals per dose:
6 animals / dose
Details on study design:
Induction: Days 0 – 20.
On Day 0, 0.1 mL of the test material undiluted and at progressively diluted solutions were applied to an area measuring 8 cm2 on the clipped flank skin of six guinea pigs per concentration groups.
The applications were repeated daily for three weeks, or done 5 times weekly during four weeks, always using the same skin site. Te application site was left uncovered. If very strong skin reactions were provoked then the application site was changed.

Challenge: Days 21 to 35.
To determine whether or not contact sensitisation was induced, all groups of guinea pigs previously treated for 21 days, as well as 6 to 8 untreated or only with the vehicle pre-treated controls are tested on Days 21 and 35 on the contralateral flank with the test material at the minimal irritating and some lower concentrations. The minimal irritating concentration of each material is used in order to confirm the biological activity determined before starting the induction (Day -1) and to exclude false results based on instability of the test materials. These tests are performed by applying with a pipette 0.025 mL of each concentration to skin areas measuring 2 cm2, the reactions being read after 24, 48 and / or 72 hours. This procedure enables to determine the minimal sensitising concentration necessary for inducing allergic contact hyper-sensitivity and the minimal eliciting concentration necessary to cause a positive reaction.
The test material is considered allergenic at a concentration when at least one out of the eight animals of this concentration group shows positive reactions with non-irritant concentrations used for challenge, i.d. its threshold concentration causing skin-reactions is shifted to the lower part of the concentration range used for challenge.
Reading:
1st reading
Hours after challenge:
504
Group:
test group
Dose level:
100 %
No. with + reactions:
0
Total no. in group:
6
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 504.0. Group: test group. Dose level: 100 %. No with. + reactions: 0.0. Total no. in groups: 6.0.

Capacity to cause allergic sensitisation

After daily applications over 3 weeks

Concentration %

Sensitisation rate number of animals

Positive / total

Day 21

Day 35

100

0 / 6

0 / 6

30

0 / 6

0 / 6

10

0 / 6

0 / 6

3

0 / 6

0 / 6

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The test substance does not sensitise the guinea pig.
Executive summary:

The test substance was assessed for skin sensitisation potential using an open epicutaneous test on guinea pigs. The test substance was not sensitising under the conditions of the test.

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

Induction on Day 0 using 0.1 mL of the test material undiluted and at progressively diluted solutions was applied to an area measuring 8 cm2 on the clipped flank skin of six guinea pigs per concentration groups. The applications were repeated always using the same skin site.

To determine whether or not contact sensitisation was induced, all groups of guinea pigs previously treated for 21 days were tested on Days 21 and 35 on the contralateral flank with the test material at the minimal irritating and some lower concentrations using 0.025 mL of each concentration to skin areas measuring 2 cm2.

There were no skin sensitisation reactions at any concentration tested.

The result of the in vitro DPRA assay when used as part of anintegrated approach for testing and assessment (IATA) with the in vitro KeratinoSens™assay, indicate that these congruent results give a good prediction of the sensitizer hazard particularly when predicting human data.

In this case, the in vitro DPRA assay, in vitro KeratinoSens™assay along with the in vivo guinea pig data indicates a lack of skin sensitisation and hence, no classification is warranted for Limetol.


Migrated from Short description of key information:
The test substance was assessed for skin sensitisation potential using an open epicutaneous test on guinea pigs. The test substance was not sensitising under the conditions of the test.

Justification for selection of skin sensitisation endpoint:
The study was conducted on the target substance in vivo.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

A skin sensitiser is defined as a substance that will lead to an allergic response following skin contact. Sensitisation includes two phases,

The induction of specialised immunological memory in an individual by exposure to an allergen and elicitation where the production of cell-mediated or antibody mediated allergic response by exposure of a sensitised individual to an allergen.

For skin sensitisation, an induction phase is required in which the immune system learns to react; clinical symptoms can then arise when subsequent exposure is sufficient to elicit a visible skin reaction (elicitation phase). Lower levels are usually required for elicitation than are required for induction.

Substances shall be classified as a Category 1 skin sensitiser if there is evidence in humans that the substance can lead to sensitisation by skin contact in a substantial number of persons, or if there are positive results form an appropriate animal test. When an adjuvant type guinea pig test method for skin sensitisation is used, a response of at least 30 % of the animals is considered positive. For a non-adjuvant guinea pig test a response of a t least 15 % of the animals is considered positive.

No positive skin sensitisation reactions were elicited during the study and the test substance is therefore not classified as a skin sensitiser.