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Administrative data

Description of key information

There are three good quality skin sensitisation studies, all of which give clear positive results, so they are used in a weight of evidence to make a conclusion for skin sensitising potential.

Two guinea pig maximisation studies (Hazleton, 1992; SafePharm Laboratories Ltd., 1987) conducted according to OECD 406 and in compliance with GLP gave positive results in response to N-(3-(trimethoxysilyl)propyl)ethylenediamine. A mouse Local Lymph Node Assay (BSL Bioservice, 2005) conducted according to OECD 429 and in compliance with GLP was also positive.


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:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
GLP compliance:
yes (incl. QA statement)
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method. Furthermore, the LLNA test method is not considered to be suitable for substances that contain silicon. Please refer to the attached document for further details.
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%
Topical challenge: 10%
Route:
epicutaneous, occlusive
Vehicle:
other: sterile Codex liquid paraffin
Concentration / amount:
Intradermal injections: 0.1%
Epicutaneous induction: 10%
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 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:
Vehicle or water + test article
Positive control substance(s):
yes
Positive control results:
In total, 6 substances were used as positive controls: dihydrocoumarin in solution at 20% (v/v) in ethanol for the induction and the challenge respectively; paraphenylenediamine in solution at 10 and 0.5 % (w/w) in deionised water for induction and challenge respectively; formalin in solution at 5% (w/w) in deionised water for induction and challenge respectively; penicillin G in suspension at 25 and 10% (w/w) in ethanol for induction and challenge respectively; benzocaine (Ethoform) in suspension at 25% (w/w) in absolute ethanol for induction and 10% (w/w) in sterile codex liquid paraffin for challenge.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
10% v/v
No. with + reactions:
6
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10% v/v
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
48
Group:
test chemical
Dose level:
10% v/v
No. with + reactions:
6
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
10% v/v
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
Dihydrocoumarin in solution at 20% (v/v)
No. with + reactions:
20
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
Dihydrocoumarin in solution at 20% (v/v)
No. with + reactions:
20
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
Paraphenylenediamine in solution at 10%
No. with + reactions:
11
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
paraphenylenediamine in solution at 0.5% (w/w) in deionised water
No. with + reactions:
11
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
formalin in dilution at 5% (w/w) in deionised water
No. with + reactions:
14
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
formalin in dilution at 5% (w/w) in deionised water
No. with + reactions:
14
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
penicillin G in suspension at 25% (w/w) in ethanol at 70°C
No. with + reactions:
14
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
penicillin G in suspension at 10% (w/w) in ethanol at 70°C
No. with + reactions:
14
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
Benzocaine in suspension at 25% (w/w) in absolute ethanol
No. with + reactions:
9
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
Benzocaine in suspension at 10% (w/w) in sterile Codex liquid paraffin
No. with + reactions:
9
Total no. in group:
20
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
propylene glycol
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
propylene glycol
No. with + reactions:
0
Total no. in group:
20
Remarks on result:
no indication of skin sensitisation

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 according to OECD 406 and in compliance with GLP (reliability score 1) N-(3-(trimethoxysilyl)propyl)ethylenediamine 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:

There are three good quality skin sensitisation studies, all of which give clear positive results, so they are used in a weight of evidence to make a conclusion for skin sensitising potential.

A guinea pig maximisation study conducted according to OECD 406 and in compliance with GLP (reliability score 1) provoked a positive reaction in 30% of the test animals, which demonstrated that the test substance is a skin sensitiser (Hazleton, 1992).

A second study, also a guinea pig maximisation study conducted according to OECD 406 and in compliance with GLP reports a positive reaction in 100% of the test animals (SafePharm Laboratories Ltd, 1987).

The third available skin sensitisation study is a mouse Local Lymph Node Assay conducted according to OECD 429 and in compliance with GLP. The test substance was clearly sensitising. 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 (BSL Bioservice, 2005).


Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the available information the registered substance is classified as 'Skin Sensitiser 1B' with the hazard statement 'H317: May cause an allergic skin reaction' in accordance with Regulation (EC) No 1272/2008.

Classification of N-(3-(trimethoxysilyl)propyl)ethylenediamine

(CAS#1760-24-3) for skin sensitization – Justification for subcategorization 1b

 

Two Guinea Pig Maximization Tests (GPMT) and a Local Lymph Node Assay (LLNA) are available that address the skin sensitization endpoint of

N-(3-(trimethoxysilyl)propyl)ethylenediamine.

The first GPMT (Hazleton France, 1992) was a guideline-compliant, reliable study that is adequate for the assessment of the skin sensitisation endpoint. After intradermal induction with 0.1 % of test item dissolved in liquid paraffin, the topical challenge resulted in a response rate of 30 % (6/20) both after 24 and 48 hours. In accordance with Annex I to the CLP Regulation (Table 3.4.3), a test result of ≥ 30 % responding at ≤ 0,1 % intradermal induction dose would result in a subcategorization as skin sensitising 1A, whereas a response of ≥ 30 % to < 60 % responding at > 0,1 % to ≤ 1 % intradermal induction dose would result in subcategory skin sens 1B. In conclusion, the test results formally lead to sub-category 1A, being borderline and very close to subcategorisation as a moderate sensitiser (1B).

The second GPMT (SafePharm Laboratories Ltd., 1987) resulted in a 100 % response during challenge after intradermal induction of 0.5 % test substance dissolved in distilled water. However, the test substance is unstable in water, hydrolyzing rapidly to ethylenediaminepropyl silanetriol (Parent DT50 = 0.025 h = 1.5 min). The substance that underwent testing is therefore not the registered substance, but its hydrolysis product. Therefore, the result of this test has limited relevance for classification and labelling of N-(3-(trimethoxysilyl)propyl)ethylenediamine

.

In a murine Local Lymph Node Assay (BSL Bioservice, 2005) conducted according to OECD 429 and in compliance with GLP (reliability score 1) N-(3-(trimethoxysilyl)propyl)ethylenediamine was clearly sensitizing. 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 EC3 is derived by calculating the average of the concentrations relating to stimulation indices below and above 3 (= 2.5 at 10 % and 4.7 at 25 % test item concentration), resulting in an EC3 of 21.9 % test item concentration, which is one order of magnitude higher than the EC3 of 2 % indicated in tables 3.4.3 and 3.4.4 in Annex I to the CLP regulation as discriminating between skin sensitisation 1A and skin sensitisation 1B. An EC3 of 10 % or higher is indicative of weak skin sensitisation potency (ECETOC, 2003; Loveless, 2010)

The LLNA EC3 has shown a high concordance with NOAELs from human data (human repeat insult patch tests (HRIPT) and human maximization tests (HMT) in various analyses (see e.g. Gerberick, 2001; Schneider, 2004; Roberts, 2018; ICCVAM, 2011), with an overall accuracy of approximately 80 % in various data sets.

The LLNA has been shown to deliver false positive results with some irritating substances (OECD 429), specifically with some organosilicon compounds (Petry, 2012). Therefore, the conduction of LLNAs for organosilicon compounds, especially those with irritation potential, is not deemed appropriate. N-(3-(trimethoxysilyl)propyl)ethylenediamine

has shown irreversible damage to eyes, resulting in classification as eye damage category 1, and local effects in a skin irritation assay that was below the threshold of classification. Also, it is an aminofunctional silicon compound such as several of the investigated substances in Petry (2012) which gave false positive results. In conclusion, an existing LLNA is believed to be possibly over-predictive.

For the above reasons, the possibility of the LLNA delivering an under-predictive result can be excluded with reasonable scientific certainty. In conclusion, based on a weight-of-evidence assessment of the existing data set, a classification as skin sensitisation 1B is believed to be appropriate.

 

ECETOC (2003). Contact Sensitisation: Classification According to Potency. Technical Report No. 87. Public available at http://www.ecetoc.org/wp-content/uploads/2014/08/ECETOC-TR-087.pdf

Gerberick GF, Robinson MK, Ryan CA, Dearman RJ, Kimber I, Basketter DA, Wright Z, Marks JG (2001). Contact allergenic potency: correlation of human and local lymph node assay data. Am J Contact Dermat. 12:156-61.

Interagency Coordinating Committee on the Validation of Alternative Methods (2011). Final Background Review Document: Use of the Murine Local Lymph Node Assay for Potency Categorization of Chemicals Causing Allergic Contact Dermatitis in Humans. Appendix C. National Toxicology Program. Public available athttps://ntp.niehs.nih.gov/iccvam/docs/immunotox_docs/llna-pot/3-appc-brd-body.pdf

Loveless S.E., Api A.-M., Crevel R.W.R., Debruyne E., Gamer A. Jowsey I.R., Kern P. Kimber I. Lea L., Mehmood Z., Steiling W., Veenstra G. Woolhiser M., Hennes C. (2010). Potency values from the local lymph node assay: Application to classification, labelling and risk assessment. Regulatory Toxicology and Pharmacology 56: 54-66

OECD Guideline for the testing of chemical No. 429. Skin sensitisation: Local Lymph Node Assay. Adopted 22 July 2010. Public available athttps://www.oecd-ilibrary.org/docserver/9789264071100-en.pdf?expires=1527838384&id=id&accname=guest&checksum=56153D1A0B70153BDCC55FD23896E497

Petry T, Bosch A, Coste X, Dupuis V, Eigler D, Germain P (2012). An assessment of the skin sensitisation hazard of a group of polyfunctional silicones using a weight of evidence approach. Regul Toxicol Pharmacol. 64(2):305-14

Roberts DW, Api A.-M. (2018). Chemical applicability domain of the local lymph node assay (LLNA) for skin sensitization potency. Part 4. Quantitative correlation of LLNA potency with human potency. Regulatory Toxicology and Pharmacology 96:76-84

Schneider K, Akkan Z (2004). Quantitative Relationship between the local lymph node assay and human skin sensitization assays. Regulatory Toxicology and Phamacology 39: 245-255