Hexamethylene diisocyanate, trimers, reaction products with 2-hydroxyethyl acrylate

Endpoint summary

Description of key information

Skin sensitisation (OECD 406): sensitising

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:

03 Aug - 27 Aug 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted in 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

adopted in 2008

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Version / remarks:

adopted in 2003

GLP compliance:

yes (incl. QA statement)

Remarks:

OGYÉI, National Institute of Pharmacy and Nutrition, Budapest, Hungary

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The study was conducted prior to the current requirement in Regulation (EC) 1907/2006 to perform an LLNA study (OECD 429) as the preferred in vivo skin sensitisation study.

Species:

guinea pig

Strain:

other: CRL:HA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Sulzfeld, Germany
- Females nulliparous and non-pregnant: yes
- Age at study initiation: approximately 10 weeks
- Weight at study initiation: 467 - 524 g
- Housing: 5 animals of the same sex per cage in macrolon cages size IV, certified wood chips bedding (Lignocel 3/4-S, J. Rettenmeier & Söhne GmbH+CO.KG, Rosenberg, Germany)
- Diet: Cunigra Diet for Rabbits (Bonafarm-Bábolna Takarmány Ltd., Hungary), ad libitum
- Water: tap water containing 50 mg/100 mL ascorbic acid, ad libitum
- Acclimation period: 41 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.4 - 25.0
- Humidity (%): 31 - 84
- Air changes (per hr): 15 - 20
- Photoperiod (hrs dark / hrs light): 12 / 12

Route:

intradermal

Vehicle:

other: 1% (w/v) ethanol in sesame oil

Concentration / amount:

1% (0.1 mL/site)

Day(s)/duration:

single injection

Adequacy of induction:

other: highest technically achievable concentration used in a dose-range-finding study for intradermal induction and induced mild-to-moderate erythema (score 1) in 2/2 animals

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

100% (0.5 g/site)

Day(s)/duration:

48 h

Adequacy of induction:

other: concentration used in a dose-range-finding study and induced slight erythema at 1 h in 2/2 animals and at 24 and 48 h in 1/2 animal

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

other: ethanol:sesame oil 2:3 (v/v) mixture with 1% (w/v) Polysorbate 80

Concentration / amount:

75% and 37.5% (w/v) (0.5 mL/site)

Day(s)/duration:

24 h

Adequacy of challenge:

other: a concentration of 75% was used in a dose-range-finding study for challenge and induced no skin reaction; the concentration of 37.5% is used as a safeguard dose

No. of animals per dose:

Dose-range-finding study: 2
Main study: 5 (controls), 10 (test groups)

Details on study design:

RANGE FINDING TESTS:
For the dose range-finding for intradermal induction two animals were given intradermal injections with 0.1 mL of 0.05, 0.1, 0.5 and 1% test substance in 1% (w/v) ethanol in sesame oil. In the first intradermal preliminary study, 5% test item was also tested in a 1:1 mixture (v/v) of Freund's Complete Adjuvant and physiological saline solution. The evaluation of the injection sites 1, 24, 48 and 72 h after injection showed no more than mild-to-moderate erythema (score 1) at the highest intradermal concentration (1%). Thus, 1% of the test substance was selected for the intradermal induction. For topical induction two animals were applied 25, 50 and 75% (w/v) test substance in ethanol:sesame oil 2:3 (v/v) mixture with 1% (w/v) Polysorbate 80 as vehicle as well as the undilutetd rest substance (100%) under occlusive conditions for 48 h. The skin reactions were evaluated 1, 24, 48 and 72 h after patch removal and based on the findings 100% of the test substance was selected for epicutaneous induction. Since the undiluted test substance caused slight erythema at 1 h in 2/2 animals and at 24 and 48 h in 1/2 animal a concentration of 75% was selected for challenge exposure. As a safeguard dose, 37.5% were selected for challenge exposure, additionally.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single injection (intradermal) and 48 h (epicutaneous)
- Test groups:
Injection 1: Freund's Complete Adjuvant and physiological saline solution in a 1:1 (v/v) mixture
Injection 2: 1% test item in the intradermal vehicle (1% (w/v) ethanol in sesame oil)
Injection 3: 1% test item formulated in a 1:1 mixture (v/v) of Freund's Complete Adjuvant and physiological saline solution
Epicutaneous: 0.5 g of the undiluted test substance
- Control group:
Injection 1: Freund's Complete Adjuvant and physiological saline solution in a 1:1 (v/v) mixture
Injection 2: intradermal vehicle (1% (w/v) ethanol in sesame oil)
Injection 3: intradermal vehicle (1% (w/v) ethanol in sesame oil) formulated in a 1:1 mixture (v/v) of Freund's Complete Adjuvant and physiological saline solution
Epicutaneous: 0.5 mL of the dermal vehicle (ethanol:sesame oil 2:3 (v/v) mixture with 1% (w/v) Polysorbate 80)
- Site: scapular region
- Frequency of applications: single injection (intradermal), single application (epicutaneous induction; one week after intradermal application)
- Duration: 9 days
- Concentrations: intradermal induction 1%, epicutaneous 100%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: two weeks after topical induction
- Exposure period: 24 h
- Test groups: 75% and 37.5% (w/v) test substance in dermal vehicle (ethanol:sesame oil 2:3 (v/v) mixture with 1% (w/v) Polysorbate 80)
- Control group: 75% and 37.5% (w/v) test substance in dermal vehicle (ethanol:sesame oil 2:3 (v/v) mixture with 1% (w/v) Polysorbate 80)
- Site: left and right side
- Concentrations: 75% and 37.5%
- Evaluation (hr after challenge): 24 and 48 h after patch removal

OTHER:
- Clinical signs: The animals were observed for clinical signs at least once daily throughout the entire study period. Detailed clinical observations were performed before the first treatment and at least weekly thereafter.
- Body weights: The body weights of the animals were recorded before the first treatment and at least weekly thereafter.

Challenge controls:

The control group is actually a challenge control.

Positive control substance(s):

yes

Remarks:

2-Mercaptobenzothiazole formulated in 1% methyl cellulose (intradermal induction: 1% (w/v), epicutaneous induction: 75% (w/v), challenge: 50% (w/v))

Positive control results:

Challenge with 2-Mercaptobenzothiazole resulted in a positive response in test animals previously sensitised. The net response values at the 24 and 48 h observations represented an incidence rate of 80% and 70% and net score values of 0.80 and 0.70, respectively. In the control animals no visible changes were found either at the 24 or 48 h examinations following challenge with the reference item. The dermal scores represented discrete erythema (score 1) developed on the skin of sensitised guinea pigs.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

Induction: 0%, challenge: 75% and 37.5% (w/v)

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No clinical signs were observed.

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Induction: 1% (intradermal) and 100% (epicutaneous); challenge: 75%

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

No clinical signs were observed.

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Induction: 1% (intradermal) and 100% (epicutaneous); challenge: 37.5%

No. with + reactions:

9

Total no. in group:

10

Clinical observations:

No clinical signs were observed.

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

Induction: 0%; challenge: 75% and 37.5%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No clinical signs were observed.

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Induction: 1% (intradermal) and 100% (epicutaneous); challenge: 75%

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

No clinical signs were observed.

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Induction: 1% (intradermal) and 100% (epicutaneous); challenge: 37.5%

No. with + reactions:

10

Total no. in group:

10

Clinical observations:

No clinical signs were observed.

Remarks on result:

positive indication of skin sensitisation

- Body weights:

At the end of the study, the mean body weight of the treatment group animals was in the same range than that of the control group animals.

Interpretation of results:

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

Conclusions:

CLP: Skin sens 1A, H317

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

A reliable study regarding skin sensitisation is available for the test substance. A study for respiratory sensitisation potential is not available.

The skin sensitisation potential of the test substance was assessed in a Guinea Pig Maximisation Method (GPMT) performed according to OECD Guideline 406 and in compliance with GLP (Weisz, 2016). 15 female CRL:HA guinea pigs were used (10 animals as test group, 5 animals as control group) to evaluate skin sensitising effects. For intradermal treatments the test material was formulated in 1% (w/v) ethanol in sesame oil and for dermal treatments in an ethanol:sesame oil 2:3 (v/v) mixture with 1% (w/v) Polysorbate 80. The induction and challenge concentrations were determined in a range-finding study with 8 female guinea pigs. The intradermal induction was conducted by administration of three pairs of injections. The first pair of injections was of Freund's complete adjuvant (FCA) diluted 1:1 in physiological saline, the second pair was of 1% of the test substance in the intradermal vehicle, and the third pair of injections was of 1% of the test substance with FCA. The control group received three pairs of injections that were the same as the test group except for the absence of the test material. One week following intradermal induction an epicutaneous induction under occlusive conditions for 48 h was performed. For the test group, the patches contained approximately 0.5 g of the undiluted test substance, while for the control group the patches contained 0.5 mL dermal vehicle. Three weeks after the intradermal induction the animals were challenged with 75% and 37.5% (w/v) of the test substance under occlusive conditions for 24 h. Skin reactions were evaluated at 24 and 48 h after patch removal. In addition, clinical signs and body weights were evaluated. No mortality, clinical signs or differences in body weights in treated and control animals were noted. The incidence rate of sensitization response was 100% at the challenge treatment site with 75% (w/v) of the test substance and 90% with 37.5% (w/v) test substance at 24 h. Discrete erythema (score 1 or 2) were developed on the skin of the test group with 75% (w/v) and 37.5% (w/v) of the test substance. The means of the scores at the 24 h and 48 h observation were 1.30 and 1.40, respectively, at the site of the maximum dermal challenge dose and 1.20 and 1.30 at the site exposed to 37.5% (w/v) of the test substance. Mean score of the control animals was 0.00 according to the 24 and 48 h results. Thus, under the conditions of this study, the test substance is classified as Skin Sensitizer Category 1A according to Regulation (EC) No 1272/2008.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The test substance is classified as Skin Sensitiser Category 1A according to Regulation (EC) 1272/2008.