2,2,3-trimethylbutane

Endpoint summary

Description of key information

Acute toxicity oral LD₅₀ >5000 mg/kg bw in rats (OECD TG 401)

Acute toxicity dermal LD₅₀ >2000 mg/kg bw in rabbits

Acute toxicity inhalation LC₅₀ >33520 mg/m³ in rats (OECD TG 403)

 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles, acceptable for assessment.

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 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

Limit test with 5000 mg/kg versus 2000 mg/kg as per guideline

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

Limit test with 5000 mg/kg versus 2000 mg/kg as per guideline

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Doses:

5000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: observations daily; weighing on initiation and on days 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Mortality:

No mortality occurred in any test animal over the 14-day observation period.

Clinical signs:

other: Clinical observations noted one-hour post exposure in 8 of 10 animals included depression, salivation, wheezing, rough coat, and soft feces. Two female rats appeared normal throughout the study. All animals appeared normal from day 2 through termination

Gross pathology:

No abnormal gross pathology findings were noted in any of the animals upon necropsy.

Interpretation of results:

other: not classified

Remarks:

Criteria used for interpretation of results: other: GHS, EU, 2007

Conclusions:

Based on the study design the test substance, 2,2,4-trimethylpentane, needs not to be classified.

Executive summary:

Based on the study design the test substance, 2,2,4 -trimethylpentane, needs not to be classified.

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

1961

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions (limited documentation).

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 401 (Acute Oral Toxicity)

Principles of method if other than guideline:

Study was performed before actual guideline was established. Limited documentation.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 101 - 132 g
- Fasting period before study: Food was withheld from the animals for a period of 3 to 4 hours prior to dosage.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 0.1, 1.0 or 10 % volume/volume solution in corn oil (Mazola)

Doses:

31.6; 100; 316; 1000; 3160; and 10,000 µL/kg body weight

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations (mortality and toxic effects): immediately after administration; at 1, 4 and 24 hours; and once daily thereafter for a total of 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: body weight, pathology (brain, liver, kidney), blood levels were collected by exsanguination

Statistics:

no data

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

> 10 mL/kg bw

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

> 7 100 - 7 800 mg/kg bw

Remarks on result:

other: recalculated values based on the LD50 of 10 mL/kg bw; the range is due to the range of density (0.71-0.78 g/cm3)

Mortality:

The test material produced no deaths at any dosage level tested.

Gross pathology:

There were no pathological findings in any animal at autopsy following sacrifice.

Other findings:

The animals at all dosage levels seemed normal in appearance and behaviour following intubation and daily during the 14 -day observation period.

The acute oral LD50 of MRD-61-33 for male albino rats is therefore greater than 10 mL/kg body weight corresponding to 7100 - 7800 mg/kg bw.

Interpretation of results:

other: Not classified

Remarks:

Criteria used for interpretation of results: other: CLP

Conclusions:

Under the conditions of this study the test substance, hydrocarbons, C7-C9, isoalkanes, does not need to be classified.

Executive summary:

Under the conditions of this study the test substance, hydrocarbons, C7-C9, isoalkanes, does not need to be classified.

Reference 3

Endpoint:

acute toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

July - September 1961

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions. Limited documentation.

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 401 (Acute Oral Toxicity)

Principles of method if other than guideline:

Study was performed before actual guideline was established.

GLP compliance:

no

Test type:

standard acute method

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 101 - 132 g
- Fasting period before study: Food was withheld from the animals for a period of 3 to 4 hours prior to dosage.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 0.1, 1.0 or 10 % volume/volume solution in corn oil (Mazola)

Doses:

31.6; 100; 316; 1000; 3160; and 10,000 µL/kg body weight

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations (mortality and toxic effects): immediately after administration; at 1, 4 and 24 hours; and once daily thereafter for a total of 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: body weight, pathology (brain, liver, kidney), blood levels were collected by exsanguination

Statistics:

no data

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

> 10 mL/kg bw

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

> 7 100 - 7 800 mg/kg bw

Remarks on result:

other: recalculated values based on the LD50 of 10 mL/kg bw; the range is due to the range of density (0.71-0.78 g/cm3)

Mortality:

The test material produced no deaths at any dosage level tested.

Gross pathology:

There were no pathological findings in any animal at autopsy following sacrifice.

Other findings:

The animals at all dosage levels seemed normal in appearance and behaviour following intubation and daily during the 14 -day observation period.

The acute oral LD50 of MRD-61-33 for male albino rats is therefore greater than 10 mL/kg bw corresponding to 7100 - 7800 mg/kg bw.

Interpretation of results:

other: Not classified

Remarks:

Criteria used for interpretation of results: other: CLP

Conclusions:

Under the conditions of this study the test substance, hydrocarbons, C7-C9, isoalkanes, does not need to be classified.

Executive summary:

Under the conditions of this study the test substance, C7-C9, isoalkanes, does not need not to be classified.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 5 000 mg/kg bw

Quality of whole database:

Three key read across studies from structural analogues available for assessment.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles, acceptable for assessment. Vapour generation and analysis not well documented.

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 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

- limit test concentration: 5 mg/L

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Duration of exposure:

4 h

Concentrations:

33.52 mg/L nominal concentration
21561.5 ± 776.32 ppm mean analytical concentration

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: day 2, 3, and 4 mentioned, not further specified
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Statistics:

not reported

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 33.52 mg/L air (nominal)

Exp. duration:

4 h

Mortality:

No mortality occurred during the 14-day observattion period.

Clinical signs:

other: Exposure-related observations noted in all animals during the exposure period included lying prostrate in the cage and rapid respiration. All animals appeared normal throughout the post exposure period.

Body weight:

Sightly decreased body weights were noted in the males on day 2 post exposure and in the females on days 2, 3 and 4 post exposure.

Gross pathology:

No abnormal gross pathology observations were noted in any animals upon necropsy.

Inhalation LC50 > 33.52 mg/L air (nominal) for 4 hours in male and female rats.

Interpretation of results:

other: not classified

Remarks:

Criteria used for interpretation of results: other: GHS, EU, 2007

Conclusions:

Based on the study design the test substance, 2,2,4-trimethylpentane, needs not to be classified.

Executive summary:

Based on the study design the test substance, 2,2,4 -trimethylpentane needs not to be classified.

Reference 2

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions. Limited documentation.

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

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 21 mg/L air (analytical)

Exp. duration:

4 h

Remarks on result:

other: 21 mg/L correspond to 4504 ppm.

Mortality:

no mortality

Clinical signs:

other: During exposure (after 2 of 4 hours), the dosed animals showed signs for irritation (eye, nose and throat). Dosed animals also appeared to be more alert than control animals after 2 hours of dosing. After exposure 3 of 12 rats had dried red nasal dischar

Body weight:

Mean animal body weights for all males and females were unremarkable at all weighing intervals.

Gross pathology:

There were 7 control rats and 8 dosed rats without abnormalities at necropsy. Of the remainder, there was a greater incidence of focal lung discoloration in the controls than in the dosed rats, a comparable incidence of dilated renal pelvis, and one instance of a dosed rat having a broken upper incisor. None of these observations was considered to be related to treatment with the test substance.

Interpretation of results:

other: Not classified

Remarks:

Criteria used for interpretation of results: EU

Executive summary:

This data is being read across from the source study that tested Hydrocarbons, C7-C9, isoalkanes based on analogue read across.

Reference 3

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions. Only 6 males tested per dose level, limited documentation on environmental conditions.

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 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

Study was performed before actual guideline was established.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: adult
- Weight at study initiation: mean weight range: 254 - 397 g
- Fasting period before study: no
- Housing: in groups
- Diet (e.g. ad libitum): ad libitum during pre-and postexposure period
- Water (e.g. ad libitum): ad libitum during pre-and postexposure period
- Acclimation period: yes, duration not reported

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dynamic exposure chamber
- Exposure chamber volume: 20 liter
- Method of holding animals in test chamber: none
- System of generating particulates/aerosols: The compound was mixed with air and metered: room air was passed through the heated test substance in a fritted-disc glass gas washing bottle. Different chamber concentrations were obtained by: 1) dilution of the saturated main air stream with make-up air in varying ratios, or 2) elevating the generation temperature and thus increasing the vapour pressure to provide a supersaturated vapour. The test material vapour was generated at 75°F (23.9°C).
- Method of particle size determination: not applicable


TEST ATMOSPHERE
- Brief description of analytical method used: 1) Determination of the ratio of the net loss of material to the total air flow volume for the period of exposure; 2) Sampling with a Model 40 M.S.A. Combustible Gas Meter standardized against pentane. The latter method required the use of a correction for each reading due to a Lower Explosive Limit of 1.4 for pentane and of 1.0 for the test compound.
- Samples taken from breathing zone: no


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: not applicable, vapour

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Sampling with a Model 40 M.S.A. Combustible Gas Meter standardized against pentane

Duration of exposure:

4 h

Concentrations:

1850, 3100, 5750, 10000 ppm

No. of animals per sex per dose:

6 males

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, histopathology (not performed, but sections of lungs, liver, spleen, kidneys, adrenals and testes were prepared for possible future analysis)

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

4 240 ppm

Exp. duration:

4 h

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

17.3 - 22.2 mg/L air

Exp. duration:

4 h

Remarks on result:

other: Recalculated values based on the LC50 of 4240 ppm; the range of LC50 is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9.

Mortality:

1850 ppm: 0/6
3100 ppm: 0/6
5750 ppm: 6/6
> 10000 ppm: 6/6

Clinical signs:

other: Exposure to lethal concentrations induced a rapid and dramatic response. Repeated episodes of violent epileptiform convulsions, interspersed with periods of running and jumping. If the animal succumbed, it was always in a position with all four legs fully

Gross pathology:

The lungs of animals which died during exposure showed hemorrhagic areas with gray spots on the surfaces. Severe lung congestion was an isolated finding and lung consolidation was seen infrequently. In general, the livers and kidneys were congested in these animals, but all other organs appeared normal. Animals surviving the 14-day observation period revealed little of interest at autopsy. In a few instances, hemorrhagic areas were noted on the lung surfaces and an occasionally darkened liver or kidney was seen. All other organs appeared normal.

Vapour concentrations in the air in the range of 0.5 to 1.0 % are easily produced by the volatilization of the test substance at room temperature.

Interpretation of results:

other: Harmful

Remarks:

Criteria used for interpretation of results: expert judgment

Conclusions:

The LC50 value was calculated to be 4240 ppm, corresponding to 17300 -22200 mg/m³ (recalculated values based on the LC50 of 4240 ppm). The range of LC50 is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9.

Due to the unknown composition of the test substance of hydrocarbons of varying chain length (C7-C9), there is the possibility of a recalculated LC50 below 20 mg/L. Therefore, the test substance should be classified as harmful if inhaled (Category 4) according to the criteria of the CLP.

Executive summary:

The LC₅₀ value was calculated to be 4240 ppm, corresponding to 17300 -22200 mg/m³ (recalculated values based on the LC50 of 4240 ppm). Ther ange of LC₅₀ is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9.

Due to the unknown composition of the test substance of hydrocarbons of varying chain length (C7-C9), there is the possibility of a recalculated LC₅₀ below 20 mg/L. Therefore, the test substance should be classified as harmful if inhaled (Category 4) according to the criteria of the CLP.

Reference 4

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions. Only 6 males tested per dose level, limited documentation on environmental conditions.

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 403 (Acute Inhalation Toxicity)

Principles of method if other than guideline:

Study was performed before actual guideline was established.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: adult
- Weight at study initiation: mean weight range: 272 - 318 g
- Fasting period before study: no
- Housing: in groups
- Diet (e.g. ad libitum): ad libitum during pre-and postexposure period
- Water (e.g. ad libitum): ad libitum during pre-and postexposure period
- Acclimation period: yes, duration not reported

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dynamic exposure chamber
- Exposure chamber volume: 20 liter
- Method of holding animals in test chamber: none
- System of generating particulates/aerosols: The compound was mixed with air and metered: room air was passed through the heated test substance in a fritted-disc glass gas washing bottle. Different chamber concentrations were obtained by: 1) dilution of the saturated main air stream with make-up air in varying ratios, or 2) elevating the generation temperature and thus increasing the vapour pressure to provide a supersaturated vapour. The test material vapour was generated at 75°F (23.9°C).
- Method of particle size determination: not applicable


TEST ATMOSPHERE
- Brief description of analytical method used: 1) Determination of the ratio of the net loss of material to the total air flow volume for the period of exposure; 2) Sampling with a Model 40 M.S.A. Combustible Gas Meter standardized against pentane. The latter method required the use of a correction for each reading due to a Lower Explosive Limit of 1.4 for pentane and of 1.0 for the test compound.
- Samples taken from breathing zone: no


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: not applicable, vapour

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Sampling with a Model 40 M.S.A. Combustible Gas Meter standardized against pentane

Duration of exposure:

4 h

Concentrations:

1050, 2390, 4450, 7140 ppm

No. of animals per sex per dose:

6 males

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs (histopathology was not performed, but sections of lungs, liver, spleen, kidneys, adrenals and testes were prepared for possible future analysis)

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

4 450 ppm

Exp. duration:

4 h

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

18.2 - 23.3 mg/L air (analytical)

Exp. duration:

4 h

Remarks on result:

other: Recalculated values based on the LC50 of 4450 ppm; the range of LC50 is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9.

Mortality:

1050 ppm: 0/6
2390 ppm: 0/6
4450 ppm: 3/6
> 7140 ppm: 6/6

Clinical signs:

other: Animals exposed to lethal concentrations exhibited clonic convulsions, laboured respiration, ataxia, and prostration preterminally. At the highest concentration, all six rats died within 1 hour; animals which survived 4 hours of exposure to 4450 ppm had a

Gross pathology:

The lungs of animals which died during exposure showed hemorrhagic areas with gray spots on the surfaces. Severe lung congestion was an isolated finding and lung consolidation was seen infrequently. In general, the livers and kidneys were congested in these animals, but all other organs appeared normal. Animals surviving the 14-day observation period revealed little of interest at autopsy. In a few instances, hemorrhagic areas were noted on the lung surfaces and an occasionally darkened liver or kidney was seen. All other organs appeared normal.

Vapour concentrations in the air of the order of 0.5 to 1.0 % are easily produced by the volatilization of the test substance at room temperature.

Interpretation of results:

other: Harmful

Remarks:

Criteria used for interpretation of results: expert judgment

Conclusions:

The LC50 value was calculated to be 4450 ppm, corresponding to 18200 -23300 mg/m³ (recalculated values based on the LC50 of 4450 ppm). The range of LC50 is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9.

Due to the unknown composition of the test substance of hydrocarbons of varying chain length (C7-C9), there is the possibility of a recalculated LC50 below 20 mg/L. Therefore, the test substance should be classified as harmful if inhaled (Category 4) according to the criteria of the CLP.

Executive summary:

The LC₅₀ value was calculated to be 4450 ppm, corresponding to 18200 -23300 mg/m³ (recalculated values based on the LC₅₀ of 4450 ppm). The range of LC₅₀ is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9.

Due to the unknown composition of the test substance of hydrocarbons of varying chain length (C7-C9), there is the possibility of a recalculated LC₅₀ below 20 mg/L. Therefore, the test substance should be classified as harmful if inhaled (Category 4) according to the criteria of the CLP.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

> 33 520 mg/m³ air

Quality of whole database:

One key, three weight of evidence, and two supporting read across studies from structural analogues available for assessment.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: dermal

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles, acceptable for assessment.

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 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

Only 3 animals per sex versus 5 as per guideline

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

Only 3 animals per sex versus 5 as per guideline

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Type of coverage:

not specified

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2000 mg/kg bw

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: observation continuous, weighing on initiation and days 7 and 14
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, dermal score

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

No mortality occurred during the 14-day observation period.

Clinical signs:

other: All rabbits appeared normal throughout the study. Very slight dermal erythema was noted in all animals on day 1 after dosing, which persisted in one male and one female on day 3. All erythema had cleared by day 7. Very slight edema was noted in two males

Gross pathology:

No abnormal gross pathology was noted in any rabbits upon necropsy.

Interpretation of results:

other: not classified

Remarks:

Migrated information Criteria used for interpretation of results: other: GHS, EU, 2007

Conclusions:

Based on the study design the test substance, 2,2,4-trimethylpentane, needs not to be classified.

Executive summary:

Based on the study design the substance, 2,2,4 -trimethylpentane, needs not to be classified.

Reference 2

Endpoint:

acute toxicity: dermal

Type of information:

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

Adequacy of study:

key study

Study period:

July - September 1961

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

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

Principles of method if other than guideline:

Standard acute method, applying 4 different doses to the clipped, intact abdominal skin

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

other: albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 1.4 - 2.3 kg
- Housing: Throughout the observation period, the rabbits were housed individually in metal cages elevated above the droppings. Purina Rabbit Pellets and water were freely available at all times.

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: abdominal skin
- Type of wrap if used: dental daming binder; wrapped with gauze and adhesive tape


REMOVAL OF TEST SUBSTANCE
- Washing (if done): with sponge and warm water
- Time after start of exposure: 24 hours

Duration of exposure:

24 hours

Doses:

100, 316, 1000, 3160 µL/kg bw

No. of animals per sex per dose:

4

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days (daily)
- Frequency of observations and weighing: 0, 1, 4, 24 hours
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 3.16 mL/kg bw

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 200 - 2 500 mg/kg bw

Remarks on result:

other: Recalculated values based on the LD50 of 3.16 mL/kg bw; the range of LD50 is due to the range of density 0.71 -0.78 g/cm3.

Mortality:

No deaths at any dosage level.

Clinical signs:

other: Apart from 3 rabbits (2 of the 100 µL/kg dose group and one of the 3160 µL/kg dose group) which showed diarrhea for 2 to 4 days during the observation period, all animals seemed normal in appearance and behaviour throughout the study.

Gross pathology:

At autopsy, the 3 rabbits which showed diarrhea for 2 to 4 days during the observation period, exhibited pathological findings. One animals of the 100 µL/kg dose group showed paleness of the cortical portion of the kidneys. The other animals from the 100 µL/kg dose group showed an excessive amount of clear fluid in the peritoneal cavity and congested, pitted, tough kidneys. The rabbit of the high dose group showed inflammation of the intestines.

Other findings:

Dermal effects: Following removal of the binders at the end of the exposure period, the abdomens and binders were dry. At this time, the exposed skin areas of the animals showed a slight degree of erythema. Within an additional one to three days, the erythema had completely subsided in all animals. The low level animals showed no other signs of irritation during the reminder of the observation period. The high level animals showed slight or moderate desquamation during the final few days of the first week and during most of the second week. At termination, however, the exposed skin of the surviving animals was completely free of signs of irritation.

Interpretation of results:

other: Not classified

Remarks:

Criteria used for interpretation of results: other: CLP

Conclusions:

There is no need for classification.

Executive summary:

There is no need for classification.

Reference 3

Endpoint:

acute toxicity: dermal

Type of information:

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

Adequacy of study:

key study

Study period:

July - September 1961

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

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

Principles of method if other than guideline:

Standard acute method, applying 4 different doses to the clipped, intact abdominal skin

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

other: albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 1.4 - 2.3 kg
- Housing: Throughout the observation period, the rabbits were housed individually in metal cages elevated above the droppings. Purina Rabbit Pellets and water were freely available at all times.

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: abdominal skin
- Type of wrap if used: dental daming binder; wrapped with gauze and adhesive tape


REMOVAL OF TEST SUBSTANCE
- Washing (if done): with sponge and warm water
- Time after start of exposure: 24 hours

Duration of exposure:

24 hours

Doses:

100, 316, 1000, 3160 µL/kg bw

No. of animals per sex per dose:

4

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days (daily)
- Frequency of observations and weighing: 0, 1, 4, 24 hours
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 3.16 mL/kg bw

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 200 - 2 500 mg/kg bw

Remarks on result:

other: Recalculated values based on the LD50 of 3.16 mL/kg bw; the range of LD50 is due to the range of density 0.71 -0.78 g/cm3.

Mortality:

There were three deaths, one at each at the 100, 1000, and 3160 µL/kg bw levels. These deaths were apparently the result of a severe intestinal infection. Blood samples were collected by cardiac puncture. All samples were frozen

Clinical signs:

other: 100 µL/kg dose: 2 animals normal in appearance and behaviour; One animal normal until 11th day, at which time this animal showed diarrhea and on day 14 depression, labored respiration, diarrhea 316 µL/kg dose: all animals showed normal behaviour 1000 µL/k

Gross pathology:

100 µL/kg dose: congestion of the kidneys, inflammation of the samll intestine, and a large amount of fluid in the gastrointestinal tract was found in one animal sacrificed
316 µL/kg dose: no pathology observed
1000 µL/kg dose: no pathology observed
3160 µL/kg dose: firm, elevated, blanched areas on the gallbladder, and extensive amount of fluid in the peritoneal cavity, and inflammation of the intestines

Other findings:

Dermal effects: Following removal of the binders at the end of the exposure period, the abdomens and binders were dry. At this time, the exposed skin areas of the animals showed a slight degree of erythema. Within an additional one to three days, the erythema had completely subsided in all animals. The low level animals showed no other signs of irritation during the reminder of the observation period. The high level animals showed slight or moderate desquamation during the final few days of the first week and during the second week. At termination, however, the exposed skin of the surviving animals was completely free of signs of irritation.

Interpretation of results:

other: Not classified

Remarks:

Criteria used for interpretation of results: other: CLP

Conclusions:

There is no need for classification.

Executive summary:

There is no need for classification.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 2 000 mg/kg bw

Quality of whole database:

Three key read across studies from structural analogues available for assessment.

Additional information

No acute toxicity data is available for 2,2,3-Trimethylbutane. However, data is available for structural analogues, Hydrocarbons, C7-C9, isoalkanes and 2,2,4 -trimethylpentane. This data is read across to based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

Oral:

 

2,2,4-trimethylpentane

 

The acute oral LD₅₀ value in rats was greater than 5000 mg/kg for 2,2,4-trimethylpentane. Clinical observations noted one-hour post exposure in 8 of 10 animals included depression, salivation, wheezing, rough coat, and soft faeces. Two female rats appeared normal throughout the study. All animals appeared normal from day 2 through termination of the study. (Chevron Phillips, 1982).

Hydrocarbons, C7-C9, isoalkanes

The acute oral LD₅₀ value in rats was greater than 10 mL/kg for hydrocarbons, C7-C9, isoalkanes in two studies performed according to a protocol similar to OECD 401. The test material produced no deaths at any dosage level tested (31.6-10000 µL/kg body weight). There were no pathological findings in any animal at autopsy following sacrifice. The animals at all dosage levels seemed normal in appearance and behaviour throughout the study period (ExxonMobil Chemical, 1961a,b).

 

Inhalation:

2,2,4-trimethylpentane

 

Male and female Sprague-Dawley rats (5/sex/dose) were exposed to 2,2,4-trimethylpentane at a nominal concentration of 33520 mg/m³ (21561.5 ± 776.32 ppm mean analytical concentration) for 4 h in a study similar to OECD 403 (limit test). No mortality occurred during the 14-day observation period. Exposure-related observations noted in all animals during the exposure period included lying prostrate in the cage and rapid respiration. All animals appeared normal throughout the post exposure period. No abnormal gross pathology observations were noted in any animal upon necropsy. The LC₅₀ value was greater than the nominal concentration of 33520 mg/m³ (Chevron Phillips, 1982).

 

Hydrocarbons, C7-C9, isoalkanes

Hydrocarbons, C7-C9, isoalkanes, have been tested in several studies for acute inhalation toxicity following both standard (similar to OECD 403) and non-standard protocols.

 

In one study, 6 rats (male and female) were exposed to a nominal concentration of 21500 mg/m³ (21000 mg/m³ actual concentration) in a whole body chamber for 4 h. Another group of 6 animals was sham-exposed to room air and served as control. No mortalities occurred throughout the duration of the study (14 days). After exposure 3 of 12 rats had dried red nasal discharge, 1 of 12 rats had slight salivation, and 1 of 12 rats had slight lacrimation. All abnormal signs in the dosed animals were cleared by day 2 post-exposure. One control rat exhibited dried red nasal discharge on days 10 and 11 post-exposure, but this sign was considered inconsequential to the study outcome. There were 7 control rats and 8 dosed rats without abnormalities at necropsy. Of the remainder, there was a greater incidence of focal lung discoloration in the controls than in the dosed rats, a comparable incidence of dilated renal pelvis, and one instance of a dosed rat having a broken upper incisor. None of these observations was considered to be related to treatment with the test substance. The LC₅₀was greater than 21000 mg/m³, corresponding to 4504 ppm (ExxonMobil Chemical, 1985).

 

In two earlier studies, rats (6 males) were exposed for 4 h to 1850, 3100, 5750 and 10000 ppm and 1050, 2390, 4450 and 7140 ppm, respectively. In the first study, mortalities occurred at 5750 ppm (6/6) and higher. Exposure to lethal concentrations induced a rapid and dramatic response. Repeated episodes of violent epileptiform convulsions, interspersed with periods of running and jumping. Death occurred within 17 minutes for all rats tested at the highest concentration. The lungs of animals which died during exposure showed hemorrhagic areas with gray spots on the surfaces. Severe lung congestion was an isolated finding and lung consolidation was seen infrequently. In general, the livers and kidneys were congested in these animals, but all other organs appeared normal. Animals surviving the 14-day observation period revealed little of interest at autopsy. In a few instances, hemorrhagic areas were noted on the lung surfaces and an occasionally darkened liver or kidney was seen. All other organs appeared normal. The LC₅₀value was calculated to be 4240 ppm, corresponding to 17300 -22200 mg/m³. The range of LC₅₀is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9 (ExxonMobil Chemical, 1962).

 

In the second study, 3/6 and 6/6 animals died at 4450 and 7140 ppm, respectively. Animals exposed to lethal concentrations exhibited clonic convulsions, laboured respiration, ataxia, and prostration preterminally. At the highest concentration, all six rats died within 1 hour; animals which survived 4 hours of exposure to 4450 ppm had a bloody exudate around the eyes and nose at the end of the exposure period. The lungs of animals which died during exposure showed hemorrhagic areas with gray spots on the surfaces. Severe lung congestion was an isolated finding and lung consolidation was seen infrequently. In general, the livers and kidneys were congested in these animals, but all other organs appeared normal. Animals surviving the 14-day observation period revealed little of interest at autopsy. In a few instances, hemorrhagic areas were noted on the lung surfaces and an occasionally darkened liver or kidney was seen. All other organs appeared normal. The LC₅₀value was 4450 ppm, corresponding to 18200 -23300 mg/m³. As mentioned above, the range of LC₅₀is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9 (ExxonMobil Chemical, 1962).

 

Two further studies were performed on guinea pigs and rats following non-guideline procedures. In each study, 5 animals were exposed to 9400 mg/m³ for 10 min every 30 min during 4 h, yielding a total of eight 10-min exposures. In both studies, none of the guinea pigs or rats exposed died during the exposures or during the 14-day observation period which followed. No pathological, histopathological or behavioural effects were observed throughout the study. The LC₅₀value in both guinea pigs and rats was greater than 9400 mg/m³ (ExxonMobil Chemical, 1972).

 

Dermal:

 

2,2,4-trimethylpentane

 

The dermal LD₅₀ value of 2,2,4-trimethylpentane, as determined in rabbits, was greater than the limit dose of 2000 mg/kg. All rabbits appeared normal throughout the study. Very slight dermal erythema was noted in all animals on day 1 after dosing, which persisted in one male and one female on day 3. All erythema had cleared by day 7. Very slight oedema was noted in two males and one female on day 1 and cleared by day 3. Epidermal scaling was noted in one female on day 10 (Chevron Phillips, 1982). 

Hydrocarbons, C7-C9, isoalkanes

Two studies were performed in which hydrocarbons, C7-C9, isoalkanes, were applied to the clipped, intact abdominal skin of albino rabbits (4/sex/dose) at 100, 316, 1000, 3160 µL/kg bw for 24 h under occlusive conditions. In the first study, there were three deaths, one each at the 100, 1000, and 3160 µL/kg bw levels. These deaths were apparently the result of a severe intestinal infection. In the 100 µL/kg group one animals showed diarrhea on day 11 and on day 14 depression, labored respiration and diarrhoea. In the same group, congestion of the kidneys, inflammation of the small intestine, and a large amount of fluid in the gastrointestinal tract was found in one animal at necropsy. At the 3160 µL/kg level, firm, elevated, blanched areas on the gallbladder, and extensive amount of fluid in the peritoneal cavity, and inflammation of the intestines were observed.

 

In the second study, no deaths at any dosage level occurred. Apart from 3 rabbits all other animals showed normal behaviour and appearance throughout the study. Two rabbits from the lowest dose treatment showed diarrhoea for two to four days and a decrease in body weight. At autopsy one showed paleness of the cortical portion of the kidneys, the other an excessive amount of clear fluid in the peritoneal cavity and congested, pitted, tough kidneys. One rabbit of the high dose group showed inflammation of the intestines.

 

In both studies the following dermal effects were noted: After removal of the binders at the end of the exposure period, the abdomens and binders were dry. At this time, the exposed skin areas of the animals showed a slight degree of erythema. Within an additional one to three days, the erythema had completely subsided in all animals. The low dose animals showed no other signs of irritation during the remainder of the observation period. The high dose animals showed slight or moderate desquamation during the final few days of the first week and during the second week. At termination, however, the exposed skin of the surviving animals was completely free of signs of irritation.

 

The LD₅₀ value was greater than 3.16 mL/kg bw in both studies (ExxonMobil Chemical, 1961).

Justification for classification or non-classification

Based on available read across data, 2,2,3-Trimethylbutane is minimally toxic via ingestion where the LD₅₀ is >5000 mg/kg bw, via dermal exposure where the LD₅₀ is >2000 mg/kg bw, and by inhalation where the LC₅₀ is >33520 mg/m³. These findings do not warrant classification under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).

2,2.3-Trimethylbutane is classified under EU CLP guidelines as STOT Single Exposure Category 3 (narcosis) based on non-lethal narcotic effects observed in acute inhalation exposure.

 

2,2.3-Trimethylbutane is classified under EU CLP guidelines as a Category 1 aspiration hazard based on its physical and chemical properties (hydrocarbon fluid, viscosity ≤ 20.5 mm²/s).