2,3-dimethylbutane

Endpoint summary

Description of key information

Skin Irritation

Irritating to the skin

 

Ocular Irritation

Not irritating to eyes

 

Respiratory Irritation

No studies were located to indicate that 2,3-Dimethylbutane is a respiratory irritant.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1987

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it closely follows OECD guideline 404.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Sittingbourne Research Centre Breeding Unit
- Age at study initiation: 4-9 months
- Weight at study initiation: 2926-4988 g
- Housing: singly in 67 x 43 x 45 cm stainless steel, wire-mesh cages, identified by metal ear tags
- Diet (e.g. ad libitum): Standard Rabbit Diet, S.Q.C., ad libitum
- Water (e.g. ad libitum): filtered water ad libitum
- Acclimation period: at least two weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 16-19 degree C
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

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

Duration of treatment / exposure:

4 hrs

Observation period:

7 days

Number of animals:

3 male/3 female

Details on study design:

TEST SITE
- Area of exposure: Hair was short between the shoulders and hindquarters. A 2x2 cm lint patch with 0.5 ml of test substance was applied.
- Type of wrap if used: The patch was covered with a single layer of gauze held in place with an elastic adhesive bandage.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Test sites were washed with water.
- Time after start of exposure: 4 hrs

SCORING SYSTEM: Animals were scored for erythema and edema on a scale of 0 (no effects) to 4 (severe effects).

Irritation parameter:

erythema score

Basis:

mean

Remarks:

group score erythema

Time point:

24/48/72 h

Score:

0.8

Max. score:

1

Reversibility:

fully reversible within: 7 days

Irritation parameter:

edema score

Basis:

mean

Remarks:

group score edema

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

fully reversible

Irritant / corrosive response data:

SBP 60/95 LNH caused mild irritation lasting through 72 hrs.

Skin Irritation Results – SBP 60/95 LNH

Animal		Observation
		Hours				Day
		4	24	48	72	7
806-M	Erythema	1	1	1	1	0
	Oedema	0	0	0	0	0
821-M	Erythema	1	1	1	1	0
	Oedema	0	0	0	0	0
803-M	Erythema	1	1	1	0	0
	Oedema	0	0	0	0	0
812-F	Erythema	1	1	1	1	0
	Oedema	0	0	0	0	0
813-F	Erythema	1	1	1	0	0
	Oedema	0	0	0	0	0
820-F	Erythema	1	1	1	0	0
	Oedema	0	0	0	0	0

Interpretation of results:

other: Not irritating

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The average erythema score (24,48, and 72 hours) was 0.8. The average oedema score (24,48, and 72 hours) was 0.0.

Executive summary:

This study examined the skin irritancy of the test substance SBP 60/95 LNH. Groups of six rabbits had 0.5 mL of test substance applied to their dorsal skin. The test area was covered semi-occlusively, and exposure lasted 4 hrs. The test area was then washed.

Animals were scored at 30 min., 24 hrs, 48 hrs, 72 hrs, and 7 days after removal of the test substance. The average erythema score (24,48, and 72 hours) was 0.8. The average oedema score (24,48, and 72 hours) was 0.0. 

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1970

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable with restrictions because it is an acceptable well-documented publication which meets basic scientific principles.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

GLP compliance:

no

Remarks:

Pre-GLP study

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2-3 kg

Vehicle:

unchanged (no vehicle)

Controls:

other: contralateral eye used as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 ml

Duration of treatment / exposure:

72 hrs

Observation period (in vivo):

72 hrs

Number of animals or in vitro replicates:

6 males

Details on study design:

SCORING SYSTEM: Draize

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

other: 1-72 hours

Score:

0.33

Max. score:

1

Reversibility:

fully reversible within: 48 hrs

Irritation parameter:

iris score

Basis:

mean

Time point:

other: 1-72 hours

Score:

0

Max. score:

0

Reversibility:

fully reversible

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: 1-72 hours

Score:

0

Max. score:

0

Reversibility:

fully reversible

Irritation parameter:

chemosis score

Basis:

mean

Time point:

other: 1-72 hours

Score:

0

Max. score:

0

Reversibility:

fully reversible

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: 24, 48, 72 hour scores not specified

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: 24, 48, 72 hour scores not specified

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: 24, 48, 72 hour scores not specified

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

other: 24, 48, 72 hour scores not specified

Irritant / corrosive response data:

1 animal had a redness score of 1 at 24 hrs. No other signs of irritation were noted.

Interpretation of results:

other: Not irritating

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

The mean conjunctivae, chemosis, iris, and cornea scores were 0.33, 0.0, 0.0 and 0.0 respectively.

Executive summary:

This study examined the potential of hexane to cause irritation to eyes. 0.1 ml of test substance was placed in the eyes of six male rabbits. The rabbits were examined for signs of irritation at 24, 48, and 72 hrs after start of exposure.

Only 1 animal showed signs of irritation (score of 1) at 24 hrs. The mean conjunctivae, chemosis, iris, and cornea scores were 0.33, 0.0, 0.0, and 0.0 respectively. 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No irritation data is available for 2,3-Dimethylbutane. However, skin and eye irritation data is available from structural analogues, hexane solvent containing <5% n-hexane and commercial hexane. This data is read across to 2,3-dimethylbutane based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

 

Skin Irritation

 

Hexane solvent containing <5% n-hexane

In a key skin irritation study (Shell, 1987a), the skin irritancy of the test substance a hexane solvent containing <5% n-hexane was examined. Groups of six rabbits had 0.5 mL of test substance applied to their dorsal skin. The test area was covered semi-occlusively, and exposure lasted 4 hours. The test area was then washed. Animals were evaluated for erythema and oedema at 30 min., 24 hrs, 48 hrs, 72 hrs, and 7 days after removal of the test substance. The average erythema score (24,48, and 72 hours) was 0.8. The average oedema score (24,48, and 72 hours) was 0.0. 

 

In a supporting primary dermal irritation study (Exxon Chemical International, 1992), 6 male New Zealand White rabbits were dermally exposed to 0.5 mL of undiluted low n-hexane (MRD-91 -121) for 4 hours under semi-occlusive conditions. Animals then were observed for 7 days. Irritation was scored by the method of Draize. The mean erythema score from the 24, 48, and 72 hour timepoints is 0.89. The mean oedema score from the 24, 48, and 72 hour timepoints is 0 . In this study, low n-hexane is not a dermal irritant based on EU criteria.

 

In another supporting primary dermal irritation study (Exxon Chemical International, 1990), 4 male and 2 female New Zealand White rabbits were dermally exposed to 0.5 mL of undiluted low n-hexane (MRD-89 -517) for 4 hours under semi-occlusive conditions. Animals then were observed for 7 days. Irritation was scored by the method of Draize. The mean erythema score from the 24, 48, and 72 hour timepoints is 1.17. The mean oedema score from the 24, 48, and 72 hour timepoints is 0.33. In this study, low n-hexane (MRD-89 -517) is not a dermal irritant based on EU criteria.

 

Commercial hexane

A supporting study (Hine and Zuidema, 1970) examined the potential of the test substance (hexane) to cause irritation to skin. The test substance was applied to both intact and abraded skin of 6 male rabbits. The test area was covered with gauze for 24 hrs. After the exposure period, the animals were scored for irritation at 24 and 72 hrs after start of exposure. The primary dermal irritation index (PDII) was 1.92 which is calculated from the average erythema score and the average edema score. Additionally, the exposure period was 24 hours. Therefore, classification as a dermal irritant is not warranted under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).

 

Eye Irritation

 

Commercial hexane

A key study (Hine and Zuidema, 1970) examined the potential of hexane to cause irritation to eyes. 0.1 mL of test substance was placed in the eyes of six male rabbits. The rabbits were examined for signs of irritation at 24, 48, and 72 hrs after start of exposure. Only 1 animal showed signs of irritation (score of 1) at 24 hrs. The mean conjunctivae, chemosis, iris, and cornea scores were 0.33, 0.0, 0.0, and 0.0 respectively. 

 

Respiratory Irritation

 

No studies were located to indicate that 2,3-Dimethylbutane is a respiratory irritant.

Justification for classification or non-classification

Skin Irritation:

Based on the available read across data, 2,3-Dimethylbutane does not meet the criteria for classification as a skin irritant under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP). However, 2,3 -Dimethylbutane is classified as a skin irritant Category 2

H315; causes skin irritation) under Annex VI of CLP.

Ocular Irritation:

Based on the available read across data, 2,3-Dimethylbutane does not meet the criteria for classification as an ocular irritant under the new Regulation (EC) 1272/2008 on classification, labelling and packaging of substances and mixtures (CLP).

 

Respiratory Irritation:

There are no studies that warrant classification as a respiratory irritant under the new Regulation (EC) 1272/2008 on classification, labelling and packaging of substances and mixtures (CLP).