Hexamethyldisiloxane

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994/05/12 - 1996/04/11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: modified methods of CTFA Safety Testing Guidelines, published by the Cosmetic, Toiletry and Fragrancy Association on September 27, 1985, and Preclinical Safety Evaluation of Materials used in Medical Devices HIMA Report 85-1.

Deviations:

yes

Remarks:

The water contained Trihalomethane (162 μg/l) that was above the EPA recommended level of 100 μg/l.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Hexamethyldisiloxane

EC Number:

203-492-7

EC Name:

Hexamethyldisiloxane

Cas Number:

107-46-0

Molecular formula:

C6H18OSi2

IUPAC Name:

trimethyl[(trimethylsilyl)oxy]silane

Test animals

Species:

guinea pig

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS

- Source: not stated

- Age at study initiation: ca. 3 months

- Weight at study initiation: 2.31-2.59 kg

- Housing: individual housing, in conventional design stainless steel cages

- Diet: Purina 5325 Certified High Fiber Rabbit Chow, ad libitum

- Water: ad libitum

- Acclimation period: 7 day quarantine


ENVIRONMENTAL CONDITIONS

- Temperature (°F): 61-70

- Humidity (%): 40-60

- Air changes (per hr): 10-15

- Photoperiod (hrs dark / hrs light): 12/12

Test system

Type of coverage:

other: occluded, semi-occluded or open

Preparation of test site:

other: intact and abraded

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL

- Amount(s) applied (volume or weight with unit): 0.5 ml

- Concentration (if solution): undiluted

Duration of treatment / exposure:

10 applications over 14 days

Observation period:

14 days

Number of animals:

3/group

Details on study design:

TEST SITE

- Area of exposure: the back

- Type of wrap if used: For occlusive application; a cotton gauze patch covered with a piece of SARAN plastic wrap, held in place by a cotton cloth bandage taped to their hair for 24 hours. Semi-occlusive wrap; a cotton gauze patch, held in place by a cotton cloth bandage taped to the hair for 24 hours. For unocculuded applicaiton, no wrap was used.


REMOVAL OF TEST SUBSTANCE

- Washing (if done): not reported


SCORING SYSTEM: The skin responses were cored on a 0-4 scale, 0 representing no reaction and 4 representing a severe reaction.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

other: Occluded application

Basis:

other: Repeated application

Time point:

other: Repeated 14 day exposure

Max. score:

2

Remarks on result:

other: Very slight to well defined erythema. See Table 1 for complete mean values.

Results 2

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Results 3

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Results 4

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Results 5

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Results 6

Irritation parameter:

edema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Results 7

Irritation parameter:

edema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

Occlusive group: very slight to well defined erythema and moist exfoliation was observed in all animals in this group by the fourth day of testing and continued throughout the study (abraded sites were healed by the fourth test day). A difference between intact and abraded sites showed a persistence of exfoliation at the abraded sites (exfoliation was present days 4 through 6 at intact sites and days 4 through 10 at abraded sites).

Semi-occlusive group: no test material - related irritation was observed in these animals during the study (abraded sites were healed by the fourth test day). No differences were observed between the intact and abraded sites.

Unoccluded group: No irritation was observed in animals during the course of the study (abraded sites were healed by the fourth day). No differences were seen between the intact and abraded sites.

Other effects:

There were no apparent test material-related effects on clinical signs, food consumption or body weight gains. The occluded wrapped animals gained less weight than the other groups. This equivocal result was possibly due to the occlusive wrappings.

Any other information on results incl. tables

Table 1: Mean Skin irritation scores at various intervals (30 minutes scoring)

Method	Skin Response	Score after application number*
		1	2	3	4	5	6	7	8	9	10
Occlusive	ErythemaMax. score: 4	0/0	0/0	0/0	2/2	2/2	1.3/1.3	0/1	0.7/1.7	1/1.7	0/1
	Edema     Max. score: 4	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0
Semi-occlusive	ErythemaMax. score: 4	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0
	Edema     Max. score: 2	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0
Unoccluded	ErythemaMax. score: 4	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0
	Edema     Max. score: 2	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0	0/0

 *intact/abraded

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

In a test that was conducted in accordance with a suitable test guideline and in compliance with GLP, L2 did not meet the criteria for classification as a skin irritant in the EU. The study involved repeated applications over 14 days and as such exceeds the requirements of the OECD 404 skin irritation study.