Registration Dossier

Diss Factsheets

Administrative data

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).