N-[3-(trimethoxysilyl)propylcyclohexylamine]

Endpoint summary

Description of key information

Skin sensitisation (OECD 406, guinea pig): not 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:

23 Aug - 15 Oct 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

(1992)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit, Schwabach, Germany

Type of study:

Buehler test

Justification for non-LLNA method:

In a recent study by Petry et al. (unpublished) the applicability of the in vitro direct peptide reactivity assay (DPRA), the KeratinoSens™ and the human cell line activation test (h-CLAT) and in the modified myeloid U937 skin sensitization test (mMUSST) has been determined for eight members of the heterogeneous group of silicone-based substances for which in vivo data was already available. Therein, the data presented provide insights into technical challenges encountered and limitations when testing such type of polysiloxanes and silanes for skin sensitization in currently proposed in vitro models and allow only a preliminary evaluation of current proposals for the hazard assessment and classification of chemical substances for the skin sensitization endpoint solely on the basis of in vitro data. The applicability is further limited by the hydrolytic instability of the test item as well as the fact that silanol hydrolysis products can form condensation products of even lower water solubility.
It is therefore concluded that, at present, the available in vitro test methods are not suitable to correctly predict the skin sensitising potential of these types of polysiloxanes and silanes and that future work has to focus on improving the understanding of the mode of action how such materials cause skin sensitisation and identifying most suitable in vitro skin sensitisation testing strategies accordingly.
The Buehler type of sensitization test was selected since the test substance is a functional silane and the Local Lymph Node Assay as the preferred alternative has shown to provide false positive results for silicone substances.

Literature
Petry, T., Bosch, A., Coste, X., Eigler, D., Germain, P., Seidel, S. and Jean, P. A. Evaluation of in vitro assays for the assessment of the skin sensitization hazard of functional polysiloxanes and silanes (unpublished)

Species:

guinea pig

Strain:

other: Crl: HA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River, Sulzfeld, Germany
- Age at study initiation: 4 weeks
- Weight at study initiation: 301 - 348 g
- Housing: animals were kept in groups in Terfuran cages on Altromin saw fibre bedding
- Diet: autoclaved hay and Altromin 3122 maintenance diet for guinea pigs, ad libitum
- Water: tap water, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 55 ± 10
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Route:

epicutaneous, occlusive

Vehicle:

cotton seed oil

Concentration / amount:

100%

Day(s)/duration:

3 applications each lasting 6 hours

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

cotton seed oil

Concentration / amount:

12.5%

Day(s)/duration:

1 application lasting 6 hours

No. of animals per dose:

10 (controls), 20 (in test groups)

Details on study design:

RANGE FINDING TESTS
Before the initiation of the preliminary test, a solubility test was performed to define the maximum concentration which is technically applicable to the animals. The test item was found to be not soluble at a concentration of 75% in physiological saline 0.9% NaCl. Solubility was found for the vehicle cottonseed oil at a concentration of 75%. The adequate concentrations for the inductions and the challenge were determined by a preliminary test with test concentrations of 6.25, 12.5, 25, 50 and 75% in cottonseed oil. Each concentration and the undiluted test substance were applied topically to the flanks of the animals for 6 h using occlusive dressings. Two animals were treated topically with concentrations of 100 and 75% of the test substance for 6 h. One animal was treated with concentrations of 25 and 50% of the test substance for 6 h and another animal was topically treated with concentrations of 6.25 and 12.5% of the test substance for 6 h. The application sites were assessed for erythema and edema 24, 48 and 72 h after patch removal. Based on the results of the preliminary test concentrations of 100 and 12.5% were chosen for the dermal induction and the challenge application, respectively. A concentration of 12.5% was found to be the highest dose which did not cause any signs of irritation after a topical treatment over a period of 6 h.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 6 h
- Test groups: neat test substance
- Control group: concurrent no treatment
- Site: left flank
- Frequency of applications: every 7 days
- Duration: Days 0 - 21
- Concentrations: 100%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 35
- Exposure period: 6 h
- Test groups: test substance in vehicle and vehicle only
- Control group: test substance in vehicle and vehicle only
- Site: right flank (test substance), left flank (vehicle)
- Concentrations: 12.5%
- Evaluation (hr after challenge): 24 and 48 h after patch removal

Challenge controls:

The control group is actually a challenge control

Positive control substance(s):

yes

Remarks:

mercaptobenzothiazole

Positive control results:

The periodically reliability check was performed with 20 healthy female Crl: HA guinea pigs treated with mercaptobenzothiazole at concentrations of 50 and 25% (in vaseline) in the induction and challenge exposure, respectively. The sensitisation rate after application of the positive control substance was 95%, confirming the reliability of the test system.

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

Induction: 0%; challenge: 12.5%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

neither erythema nor edema observed

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Induction: 100%; challenge: 12.5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

neither erythema nor edema observed

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

Induction: 50%; challenge: 25%

No. with + reactions:

19

Total no. in group:

20

Clinical observations:

slight erythema (grade 1) were observed in 19/20 animals

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

Induction: 0%; challenge: 12.5%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

neither erythema nor edema observed

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Induction: 100%; challenge: 12.5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

neither erythema nor edema observed

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

Induction: 50%; challenge: 25%

No. with + reactions:

13

Total no. in group:

20

Clinical observations:

slight erythema (grade 1) were observed in 13/20 animals

Interpretation of results:

other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008

Conclusions:

In a skin sensitisation study (Buehler test) according to OECD guideline 406 and in compliance with GLP, the test substance caused no skin reactions identified as sensitisation at the tested concentrations (induction: 100%, challenge: 12.5%) in Crl: HA guinea pigs. Thus, the test substance is not considered to be a skin sensitizer under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Skin sensitisation

The skin sensitising properties of N-[3-(trimethoxysilyl)propylcyclohexylamine] (CAS 3068-78-8) were tested in a study according to OECD TG 406 under GLP conditions using the test for delayed contact hypersensitivity in guinea pigs (Buehler test, BSL, 2016). The Buehler test was performed on 30 female Crl: HA guinea pigs. For the dermal inductions the initially test item concentration was 100% (v/v). A 12.5% (v/v) preparation of the test item was selected for the challenge application. Topical application of the appropriate test substance concentrations (20 test animals) or vehicle (10 control animals) was performed once a week at the flanks of each animal for three consecutive weeks. Fourteen days after the last topical application of the test substance or vehicle all animals were challenged with the test substance at a concentration of 12.5% (v/v). Skin reactions of all animals were evaluated 24 and 48 hours after challenge administration. After the challenge application (12.5%) no skin reactions were observed in either the test or the control group 24 and 48 hours following 6 hours topical exposure. Periodically performed validity checks in the test strain with mercaptobenzothiazole gave the respective results. Thus, N-[3-(trimethoxysilyl)propylcyclohexylamine] (CAS 3068-78-8) was not skin sensitising under the conditions of this Buehler test.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The available data on skin sensitisation of the registered substance do not meet the criteria for classification according to Regulation (EC) No. 1272/2008, and are therefore conclusive but not sufficient for classification.