2,6-di-tert-butylphenol

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23/01/1991-06/02/1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD Guideline 404)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2,6-di-tert-butylphenol

EC Number:

204-884-0

EC Name:

2,6-di-tert-butylphenol

Cas Number:

128-39-2

Molecular formula:

C14H22O

IUPAC Name:

2,6-di-tert-butylphenol

Details on test material:

- Name of test material (as cited in study report): Phenol, 2,6-bis(1,1-dimethylethyl)
- Substance type: di-alkylphenol
- Physical state: white crystalline solid
- Analytical purity: 99.26% (GC)
- Purity test date: 03/10/1990
- Lot/batch No.: 2,6-AP/308
- Storage condition of test material: in original container at room temperature in the dark

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: David Percival Ltd., Moston, sandbach, Cheshire, UK
- Age at study initiation: approximately twelve to sixteen weeks old
- Weight at study initiation: 2.08-2.74 kg
- Housing: The animals were individually housed in suspended metal cages
- Diet: ad libitum (Spillers Rabbit Diet, Dalfety Agriculture Ltd., Almondsbury, Bristol)
- Water: ad libitum, drinking water
- Acclimation period:minimum acclimatisation period of five days


ENVIRONMENTAL CONDITIONS
- Temperature: the animal room was maintained at 17-22°C
- Humidity: 49-61%
- Air changes: approximately 15 changes per hour
- Photoperiod: 12 hrs dark / 12 hrs light

Test system

Type of coverage:

semiocclusive

Preparation of test site:

other: clipped

Vehicle:

water

Controls:

not required

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied:A quantity of 0.5 g of the test material, moistened with 0.5 ml of distilled water, was introduced under a 2.5 cm x 2.5 cm gauze patch and placed in position on the shorn skin.

Duration of treatment / exposure:

4 hours

Observation period:

1, 24, 48 and 72 hours. Additional observations were made on day 7 and 14 to assess the reversibility of the skin reactions.

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: 0.5 g of the test material, moistened with 0.5 ml of distilled water, was introduced under a 2.5 x 2.5 cm gauze patch and placed in position on the shorn skin
- Type of wrap if used: The patch was secured in position with a strip of surgical adhesive tape (BLENDERM: approximate size 2.5 x 4.0 cm). To prevent the animals interfering with the patches, the trunk of each rabbit was wrapped in an elasticated corset (TUBIGRIP) and the animals were returned to their cages for the duration of the exposure period.


REMOVAL OF TEST SUBSTANCE
- Washing (if done): corset and patches were removed from each animal and any residual test material removed by gentle swabbing with cotton wool soaked in distilled water
- Time after start of exposure: four hours


SCORING SYSTEM: according to the scale from Draize J. H. (1959) Association of Food and Drug Officials of the United States, Austin, Texas, "The appraisal of the Safety of Chemicals in Foods, Drugs and Cosmetics"

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

other: 1, 24, 48, 72 hours

Score:

1 - 2

Max. score:

4

Results 2

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

other: 7 days

Max. score:

4

Remarks on result:

other: 7 days: Adverse reactions prevented accurate evaluation of erythema. 9 days: animal killed

Results 3

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

other: 1, 24, 48, 72 hours

Score:

2

Max. score:

4

Remarks on result:

other: Haemorrhage of the dermal capillaries. Light brown discolouration of the epidermis. Thickening of the skin. Loss of skin elasticity.

Results 4

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

other: 7, 14 days

Score:

0

Max. score:

4

Reversibility:

other: reversible within 7 days

Remarks on result:

other: Crust formation after 7 d. Reduced fur re-growth after 14 days

Results 5

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

other: 1, 24, 48, 72 hours

Score:

2

Max. score:

4

Results 6

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

other: 7, 14 days

Score:

0

Max. score:

4

Reversibility:

other: reversible after 14 days

Remarks on result:

other: 7 days: adverse reactions prevented evaluation. 14 days: crust formation and reduced fur re-growth

Results 7

Irritation parameter:

edema score

Basis:

animal #1

Time point:

other: 1, 24, 48, 72 hours

Score:

1

Max. score:

4

Results 8

Irritation parameter:

edema score

Basis:

animal #1

Time point:

other: 7 days

Max. score:

4

Remarks on result:

other: 7 days: adverse reactions prevented accurate evaluation of oedema. 9 days: animal killed

Results 9

Irritation parameter:

edema score

Basis:

animal #2

Time point:

other: 1, 24, 48, 72 hours, 7 & 14 days

Score:

0 - 3

Max. score:

4

Reversibility:

fully reversible within: 7 days

Results 10

Irritation parameter:

edema score

Basis:

animal #3

Time point:

other: 1, 24, 48, 72 hours, 7 & 14 days

Score:

0 - 3

Max. score:

4

Reversibility:

fully reversible within: 14 days

Remarks on result:

other: 7 days: adverse reactions prevented accurate evaluation of oedema

Results 11

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

other: S/6, S = Sum of 24 and 72 hour reading

Time point:

other: 24, 72 hours

Score:

3.8

Max. score:

8

Remarks on result:

other: moderate irritant

Results 12

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 24, 48, 72 hours

Score:

2

Max. score:

4

Remarks on result:

other: positive criteria

Results 13

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 24, 48, 72 hours

Score:

1 - 2.3

Max. score:

4

Remarks on result:

other: positive criteria

Irritant / corrosive response data:

Very slight to well-defined erythema was noted at all treated skin sites one hour after patch removal, with well-defined erythema at all treated skin sites at the 24, 48, and 72-hours observations.

Very slight to moderate oedema was noted at all treated skin sites one and 24 hours after patch removal with very slight to slight oedema at the 48 and 72-hour observations.

Other effects:

Other adverse skin reactions noted at one treated skin site at this time were haemorrhage of dermal capillaries, light brown discolouration of the epidermis, thickening of the skin and loss of elasticity. Crust formation was noted at the 7 day observation. Hardened light brown-coloured scabs and thickening of the skin were noted at two treated skin sites at the 7 day observation. These reactions prevented accurate evaluation of erythema and oedema. Crust formation and/or reduced re-growth of fur was noted at two treated skin sites at the 14-day observation.

Any other information on results incl. tables

Key to tables:

Br = light brown discolouration of the epidermis

Cf = crust formation

Fr = reduced fur re-growth

Hd = haemorrhage of dermal capillaries

Le = loss of skin elasticity

Sp = hardened light brown-coloured scab

Th = thickening of the skin

?e = adverse reactions prevented accurate evaluation of erythema

?Od = adverse reactions prevented accurate evaluation of oedema

Individual skin reactions

Skin reaction	Observation time	Individual Scores – Rabbit Number and Sex (Bodyweight Kg)
		191 Female (2.08)	196Female (2.74)	204 Male (2.44)	Total
Erythema/eschar formation	1 h	1	2 Hd	2	(5)
	24 h	2	2 Hd	2	6
	48 h	2	2 Br	2	(6)
	72 h	2	2 BrThLe	2	6
	7 days	?eSpTh	0 Cf	?eSpTh	(0-8)
	14 days	-	0Fr	0CfFr	(0)
Oedema formation	1 h	1	3	3	(7)
	24 h	1	3	3	7
	48 h	1	2	2	(5)
	72 h	1	2	1	4
	7 days	?Od	0	?Od	(0-8)
	14 days	-	0	0	(0)
Sum of 24 and 72-Hour readings (S): 23
Primary Irritation Index (S/6): 23/6 = 3.8
Classification: Moderate irritant ( ) = total values not used for calculation of primary irritation index - = animal killed Individual daily and individual mean scores Skin reaction Reading (h) Individual Scores – Rabbit Number and Sex (Bodyweight Kg)   191 Female (2.08) 196 Female  (2.74) 204 Male (2.44)  Erythema/eschar formation  24 2 2 2   48 2 2 2   72 2 2 2   Total   6 6  6  Mean Score   2.0+ 2.0+ 2.0+   Oedema formation  24 1 3 3   48 1 2 2   72 1 2 1  Total   3 7 6  Mean Score   1.0 2.3+ 2.0+ + = positive criteria

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritant) based on GHS criteria

Conclusions:

The test material produced a primary irritation index of 3.8 and was classified as moderate irritant to rabbit skin according to the Draize Classification scheme. No corrosive effects were noted. The test material produced positive criteria in 3/3 rabbits according to the EEC labelling regulations and was classified as irritant to rabbit skin. The symbol "Xi" and risk phrase R38 "irritating to skin" are therefore required.

Executive summary:

A study was performed to assess the irritancy potential of the test material to the skin of the New Zealand White rabbit. The method used followed that described in the OECD Guidelines for Testing of Chemicals (1981) No. 404 "Acute Dermal Irritation/Corrosion" referenced as Method B4 in Commission Directive 84/449/EEC (which constitutes Annex V of Council Directive 67/548/EEC.

The results may be used as a basis for classification and labelling under Annex VI of Council Directive 67/548/EEC (as adapted to technical progress by Commission Directive 83/467/EEC).

A single 4 -hour, semi-occluded application of the test material to the intact skin of three rabbits produced well-defined erythema and very slight to moderate oedema. Other adverse skin reactions noted were haemorrhage of the dermal capillaries, light brown discolouration of the epidermis, thickening of the skin, loss of skin elasticity, crust formation, hardened light brown-coloured scab and reduced re-growth of fur.

The test material produced a primary irritation index of 3.8 and was classified as moderate irritant to rabbit skin according to the Draize Classification scheme. No corrosive effects were noted. The test material was also classified as irritant according to the EEC labelling regulations. The symbol "Xi" and risk phrase R38 "irritating to skin" are therefore required.