N-[3-(triethoxysilyl)propyl]ethylenediamine

Endpoint summary

Description of key information

Skin sensitisation (WoE, OECD 406/429): sensitising (RA from CAS 1760-24-3 and CAS 3069-29-2)

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:

weight of evidence

Study period:

16.09.1991 to 19.10.1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The test was performed in 1992 when the OECD Guideline 406 adopted in 1992 was the current version. According to this guideline "the Guinea Pig Maximisation Test (GPMT) [...] and the non-adjuvant Buehler Test are given preference over other methods".

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: young adult
- Weight at study initiation: 300-500 g
- Housing: by sex and in groups of up to 5 or 6 (2 for the preliminary studies), in polystyrene cages with perforated flooring
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20±3
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Route:

intradermal and epicutaneous

Vehicle:

other: sterile Codex liquid paraffin

Concentration / amount:

Intradermal injections: 0.1%
Epicutaneous induction: 10%

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

other: sterile Codex liquid paraffin

Concentration / amount:

Topical challenge: 10%

No. of animals per dose:

Control: 20
Test: 20

Details on study design:

Induction
Treated group:
By intradermal route: 3 series of 2 x 0.1 ml injections.
1) FCA at 50% (v/v) in an isotonic injectable solution;
2) test substance in a 0.1% (v/v) solution in sterile Codex liquid paraffin;
3) mixture 50/50 (v/v): test substance in a 0.2% (v/v) in sterile Codex liquid paraffin + FCA at 50% (v/v) in an isotonic injectable solution, i.e. a final 0.1% concentration of the test substance.

By topical occlusive route for 48 hours: with 0.5 ml of the test substance in a 10% (v/v) solution in sterile Codex liquid paraffin. As this application only provoked a weak irritation during the preliminary study, a skin painting was performed on Day 8, with 0.5 ml of sodium lauryl sulfate at 10% (w/w) in Codex paraffin.

Control: The intradermal injections and the topical occlusive application for 48 hours were carried out under the same conditions as in the treated group, sterile Codex liquid paraffin replacing the test substance.

The rest period was 11 days without treatment.

Challenge
Topical occlusive application for 24 hours performed in the treated and control groups with the test substance in a 10% (v/v) solution in
sterile Codex liquid paraffin and at a rate of 0.5 ml. The vehicle was also applied during the challenge.

The cutaneous macroscopic examinations were performed according to Magnusson & Kligman scale and to the challenge application site, 24 and 48 hours after removal of the patches. Histopathological examinations of the skin were performed for nine animals of the treated group that showed doubtful macroscopic reactions at 24 hours and for one animal of the control group, which showed abnormal macroscopic reactions at 24 hours.

Challenge controls:

The control group is actually a chellenge control.

Positive control substance(s):

not specified

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

intradermal induction 0.1 % (v/v); challenge 10% (v/v)

No. with + reactions:

6

Total no. in group:

20

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

intradermal induction 0%; challenge 10% (v/v)

No. with + reactions:

0

Total no. in group:

20

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

intradermal induction 0.1 % (v/v); challenge 10% (v/v)

No. with + reactions:

6

Total no. in group:

20

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

intradermal induction 0%; challenge 10% (v/v)

No. with + reactions:

0

Total no. in group:

20

Group:

positive control

Remarks on result:

not measured/tested

Signs of irritation were noted during the induction.

The macroscopic and histopathological examinations revealed pathological lesions of delayed hypersensitivity in 6 out of the 20 treated animals. A weak irritation was noted in one animal of the control group. No other cutaneous abnormality was noted in the 19 other guinea pigs examined in the control group.

Overall, the test substance provoked a reaction of cutaneous sensitisation in 30% of the animals examined.

Interpretation of results:

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

Conclusions:

In a guinea pig maximisation study conducted to OECD 406 and to GLP the test material provoked a positive reaction in 30% of the test animals. Hence, this test substance is considered to be a skin sensitiser.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

No data are available to assess the skin sensitisation potential of N-[3-(triethoxysilyl)propyl]ethylenediamine (CAS 5089-72-5), however, reliable data are available for the structural analogue substances N-(3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) and 3-(2-aminoethylamino)propylmethyldimethoxysilane (CAS 3069-29-2).

 

READ-ACROSS JUSTIFICATION

To reduce animal testing REACH recommends to make use of a read-across approach where appropriate based on the high accordance in properties relevant for the specific endpoint. In the case of skin sensitisation relevant properties are structural similarity as well as physical-chemical and basic toxicological parameters in the same range. In the following paragraphs the read-across approach for N-[3-(triethoxysilyl)propyl]ethylenediamine is evaluated point by point.

 

Read-across hypothesis

Four skin sensitisation studies (3 GPMT studies and 1 LLNA study) are available for the analogue substances N-[3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) and 3-(2-aminoethylamino)propylmethyldimethoxysilane (CAS 3069-29-2). All four studies gave clear positive results, thus concluding-[3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) and 3-(2-aminoethylamino)propylmethyldimethoxysilane (CAS 3069-29-2) to be skin sensitisers.

 

N-[3-(triethoxysilyl)propyl]ethylenediamine (CAS 5089-72-5), N-[3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) and 3-(2-aminoethylamino)propylmethyldimethoxysilane (CAS 3069-29-2) have a medium to high dermal absorption potential (40, 20 and 80%, respectively), corresponding to a dermal absorption of 7.79E-03, 7.11E-04 and 4.35E-02 mg/cm²/h, respectively. This prediction was calculated with DERWIN (v2.02.2012) on the basis of molecular weight (264.4, 222.4 and 206.36 g/mol), water solubility (2.4E+04, 1E+06 and 8.6E+05 mg/l), and log Kow (1.2, -1.67 and 1.0).

All three substances could undergo hydrolysis resulting in the common or similar silicon-containing hydrolysis products, N-(3-(trihydroxysilyl)propyl)ethylenediamine or 3-(2-aminoethylamino)propylmethyldihydroxyysilane, respectively. The hydrolysis products are supposed to have a dermal absorption that is higher than that of the parent substances. Since skin penetration is one essential step during skin sensitisation, it is considered appropriate to read-across this result to the other members of the aminofunctional alkoxysilane analogue group. This is supported by a larger data set of skin sensitisation studies for aminofunctional alkoxysilanes (PFA, 2013t). In addition the hydrolysis products methanol and ethanol are not sensitising to skin.

Discussion

There are four good quality skin sensitisation studies, all of which give clear positive results.

The first study is a guinea pig maximisation test, conducted with N-(3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) according to OECD 406 and in compliance with GLP. Animals were intradermally induced with 0.1% test substance solution and epicutaneously induced with 10% test substance solution. Challenge exposure was conducted with 10 % test substance formulation and provoked a positive reaction in 30% of the test animals, concluding the test substance to be a moderate skin sensitiser (Cat 1B according to Regulation (EC) No. 1272/2008) (Hazleton France, 1992). 

 

A further study, also a guinea pig maximisation test, was conducted with N-(3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) according to OECD 406 and in compliance with GLP. Animals were intradermally induced with 0.5% test substance solution and epicutaneously induced with undiluted test substance. Challenge exposure was conducted with neat test substance and provoked a positive reaction in 100% of the test animals, concluding the test substance to be a moderate skin sensitiser (Cat 1B according to Regulation (EC) No. 1272/2008) under the conditions of this test (SafePharm Laboratories Ltd, 1987).

 

Another study employed a mouse Local Lymph Node Assay, conducted with N-(3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) according to OECD 429 and in compliance with GLP. The stimulation indices for 5, 10, 25 and 50% test substance (in 3+1 (v/v) acetone/olive oil) were 1.7, 2.5, 4.7 and 7.9, respectively. The negative and positive (P-Phenylenediamine) controls gave stimulation indices of 1.0 and 12.1, respectively. Based on these results, the EC3 value was calculated at a concentration of 13% of the test substance. The test substance was therefore a moderate sensitiser (Cat 1B according to Regulation (EC) No. 1272/2008) under the conditions of this test (BSL, 2005).

 

The skin sensitising study was conducted with 3-(2-aminoethylamino)propylmethyldimethoxysilane (CAS 3069-29-2) according to OECD 406 and in compliance with GLP. The study for skin sensitisation in guinea pig reports the test substance to be an extreme sensitiser to skin as assessed by a Magnusson & Kligman Maximisation Test (SafePharm Laboratories Ltd., 1988) in accordance with OECD 406 and GLP. 19/20 test animals showed positive responses at both 24 and 48 hour readings. 

 

In conclusion, based on the available data from the structural analogues N-(3-(trimethoxysilyl)propyl]ethylenediamine (CAS 1760-24-3) and 3-(2-aminoethylamino)propylmethyldimethoxysilane (CAS 3069-29-2) it was concluded that the registered substance N-[3-(triethoxysilyl)propyl]ethylenediamine (CAS 5089-72-5) is sensitising to the skin following the weight of evidence approach.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Study not required according to Annex VII-X of Regulation (EC) No 1907/2006.

Justification for classification or non-classification

Based on reliable data from the analogue substances N-(3 -(trimethoxysilyl)propyl)ethylenediamine (CAS 1760 -24 -3) and 3-(2-aminoethylamino)propylmethyldimethoxy-silane (CAS 3069-29-2), the registered substance N-(3 -(triethoxysilyl)propyl)ethylenediamine (CAS 5089 -72 -5) is classified as Skin Sens. 1B (H317: May cause an allergic skin reaction) according to Regulation (EC) No. 1272/2008 following the weight of evidence approach.