Triethoxypropylsilane

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Pretest: 05.08.1996 to 08.08.1996. Main test: 07.10.1996 to 06.11.1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler 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.

Test material

Test material information

Constituent 1

Reference substance name:

Trimethoxypropylsilane

EC Number:

213-926-7

EC Name:

Trimethoxypropylsilane

Cas Number:

1067-25-0

Molecular formula:

C6 H16 O3 Si

IUPAC Name:

trimethoxy(propyl)silane

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmann GmbH, Borchen, GERMANY
- Age at study initiation: young adults
- Weight at study initiation: <500 g
- Housing: Makrolon Type IV, max 5/cage
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/-3
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: Pretest: 05.08.1996 to 08.08.1996. Main test: 07.10.1996 to 06.11.1996

Study design: in vivo (non-LLNA)

Induction

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

100%

Challenge

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

25%

No. of animals per dose:

20 (test group); 10 (control)

Details on study design:

RANGE FINDING TESTS: conducted with groups of 3 animals.
Applications (6 h occluded contact) of 5, 25, 50 and 100% TS with examination at 24 and 48 h following patch removal. 100% was identified as a suitable induction concentration (causing mild irritation), while 25% was identified as the lowest non-irritant challenge concentration.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3 dermal occlusive
- Exposure period: 6 h
- Test groups: 20
- Control group: 10
- Frequency of applications: application on Days 0, 7, 14
- Concentrations: TS neat or vehicle (corn oil) applied to the test and control groups, respectively (0.3 cc applied to a 2x2 cm patch)

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (at two sites: TS and vehicle)
- Day(s) of challenge: Day 28
- Exposure period: 6 h
- Test groups: 20
- Control group: 10
- Site: flank
- Concentrations: 25% TS in corn oil and neat corn oil applied to both the test and control groups.
- Evaluation (hr after challenge): 24 and 48 h following patch removal

Challenge controls:

25% TS in corn oil and neat corn oil applied to both the test and control groups.

Positive control substance(s):

yes

Remarks:

2-mercaptobenzothiazol

Results and discussion

Positive control results:

Response rate of 30% (3/10 animals) indicates that the standard allergen is a sensitizer in the guinea pig under the conditions of this study. (See table 1.)

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100% at induction, 25% at challenge

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

100% at induction, 25% at challenge

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

None

Results 3

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0% at induction, 25% at challenge

No. with + reactions:

0

Total no. in group:

10

Results 4

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0% at induction, 25% at challenge

No. with + reactions:

0

Total no. in group:

10

Results 5

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

50%

No. with + reactions:

3

Total no. in group:

10

Any other information on results incl. tables

Table 1: Incidence of dermal response to challenge dosing

GROUP	MATERIAL	INTERVAL (AFTER 6h CHALLENGE)	SKIN REACTIONS (NUMBERS OF ANIMALS)	NO. ANIMALS	SENSITIZATION INCIDENCE INDEX**
Test	TS (25%)	24h	0	20	0/20=0%
		48h	0	20
	Vehicle	24h	0	20	0/20=0%
		48h	0	20
Positive control (2-mercaptobenzothiazol)	50% MCBT in vehicle	24h	3	10	3/10=30%*
		48h	0	10
	Vehicle (Vaseline)	24h	0	5	0/5=0%
		48h	0	5
Negative (vehicle) control	TS (25%)	24h	0	10	n/a
		48h	0	10
	Vehicle	24h	0	10	n/a
		48h	0	10

* The response of 30% in the positive controls confirms that the standard allergen tested is sensitizing in guinea pig under the conditions of this study.

Applicant's summary and conclusion

Interpretation of results:

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

Conclusions:

In a guinea pig skin sensitisation study (Buehler test), conducted according to OECD 406 and in compliance with GLP (reliability score 1) the structural analogue substance trimethoxypropylsilane (CAS: 1067-25-0) was not a skin sensitiser.