2,2-dimethylbutane

Endpoint summary

Description of key information

No studies are available for the registered substance 2,2-Dimethylbutane. Based on the read-across approach, information on n-hexane is used.

One key study for skin irritation was identified (Shell, 1987a; Klimisch score=1).  One key read-across eye irritation study of C-6 normal and iso paraffins (hexanes) and naphthenes (methyl-cyclohexane, dimethylcyclohexane), 25-35% n-hexane was identified (Hine, 1970; Klimisch score = 2).

Skin Irritation - OECD 404 in rabbits - irritating to the skin, harmonised classification for skin irritation.

Eye Irritation - OECD 405 in rabbits - Not an ocular irritant

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

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. 

Reference 2

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 source

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

Reference 1

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

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. 

Reference 2

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 source

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

There is no data available for 2,2 -Dimethylbutane. Based on an analogue approach data are read-across to n-Hexane.

Skin Irritation

In a key skin irritation study (Shell, 1987a; Klimisch score = 1), 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. 

Eye Irritation

In a key read-across eye irritation study of C-6 normal and iso paraffins (hexanes) and naphthenes (methyl-cyclohexane, dimethylcyclohexane), 25-35% n-hexane (Hine, 1970; Klimisch score = 2), 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. 

Justification for classification or non-classification

2,2 -Dimethylbutane has a harmonised classification for Skin irrit. 2 (H315: Causes skin irritation) under the Regulation (EC) 1272/2008 on classification, labelling and packaging of substances and mixtures (CLP).