Registration Dossier
Registration Dossier
Data platform availability banner - registered substances factsheets
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 201-193-6 | CAS number: 79-29-8
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
![](https://echa.europa.eu./o/diss-blank-theme/images/factsheets/A-REACH/factsheet/print_toxicological-information.png)
Carcinogenicity
Administrative data
Description of key information
No standard carcinogenicity studies are available for 2,3-Dimethylbutane. However, data is available for structural analogue, 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.
Commercial hexane
Carcinogenicity Study (OECD TG 451)
Inhalation NOAEC (rat) = 31743 mg/m3
Inhalation NOAEC (mouse) = 31680 mg/m3
Key value for chemical safety assessment
Carcinogenicity: via oral route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Carcinogenicity: via inhalation route
Link to relevant study records
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Study period:
- 1990-01-23 to 1992-01-30
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: This study is classified as reliable without restriction because it followed a protocol comparable to OECD Guideline 451.
- 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
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 451 (Carcinogenicity Studies)
- GLP compliance:
- yes (incl. QA statement)
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Raleigh, North Carolina
- Age at study initiation: 8 weeks
- Weight at study initiation: approx. 167 g males, approx. 119 g females
- Housing: individually in stainless steel wire mesh cages, identified by tail tattoo
- Diet (e.g. ad libitum): Purina Certified Rodent Chow Brand Animal Diet #5002, ad libitum, except during exposure
- Water (e.g. ad libitum): Elizabethtown Water Company, ad libitum, except during exposure
- Acclimation period: 26 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23
- Humidity (%): 53 +/- 14
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark
IN-LIFE DATES: From: Jan. 23, 1990 To: Jan. 29, 1992 - Route of administration:
- inhalation: vapour
- Type of inhalation exposure (if applicable):
- whole body
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 10,000 l glass and stainless steel exposure chamber
- Method of holding animals in test chamber: individual cages
- Source and rate of air: chamber supplied air, 2000-2130 lpm
- Method of conditioning air: Test substance in a Protectoseal laboratory can passed through a fluid metering pump into teflon tubing to a coiled glass rod in the volatilization generator. Nitrogen was also fed into the volitization generator. A heating element was positioned in the center of the glass coil to aid volatilization. The nitrogen and test substance mixture then entered the exposure chamber.
- Air flow rate: 2000-2130 lpm
- Air change rate: 4.7-5.0 min.
- Method of particle size determination: TSI Aerodynamic Particle Sizer
- Treatment of exhaust air: Air was exhausted through a HEPA filter, charcoal filter, and into a MOCO incinerator. A charcoal drum was used as a back-up in case of incinerator failure.
TEST ATMOSPHERE
- Brief description of analytical method used: GC
- Samples taken from breathing zone: yes, monthly - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Hourly samples were taken from the test chamber and analyzed using a MIRAN 1A Ambient Air Analyzer. In addition, samples were taken monthly and analyzed using GC.
- Duration of treatment / exposure:
- 2 yrs, total of 511 exposures
- Frequency of treatment:
- 6 hrs/day, 5 days/week
- Remarks:
- Doses / Concentrations:
0, 900, 3000, 9000 ppm
Basis:
other: target concentration - Remarks:
- Doses / Concentrations:
0.043, 900, 3000, 9016 ppm
Basis:
analytical conc. - No. of animals per sex per dose:
- 50 per sex/per group
- Control animals:
- yes, sham-exposed
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations: mortality, toxicological and pharmacological signs
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: prior to test and weekly thereafter
BODY WEIGHT: Yes
- Time schedule for examinations: 3 times pretest, weekly for first 13 weeks, monthly thereafter
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
2 times pretest, weekly for first 13 weeks, monthly thereafter
OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: pretest, month 5, termination
HAEMATOLOGY: Yes
- Time schedule for collection of blood: pretest, month 12, month 18, termination
- Anaesthetic used for blood collection: No
- Parameters checked: differential leucocyte counts - Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
nasal cavity, cranial cavity, brain, spinal cord, thoracic cavity, abdominal cavity, pelvic cavity, and neck
HISTOPATHOLOGY: Yes
lungs, abdominal aorta, adrenals, bone, bone marrow, brain, esophagus, exorbital lacrimal gland, eyes, gonads, heart, intestine, kidneys, larynx, liver, lymph nodes, nasopharyngeal tissues, nerves, pancreas, pituitary, prostate, salivary gland, seminal vesicles, skin, spinal cord, spleen, stomach, thymic region, thyroid, trachea, urinary bladder, uterus, gross lesions, tissue masses - Statistics:
- Body weight, body weight change, and mean food consumption were statistically analyzed.
- Clinical signs:
- effects observed, treatment-related
- Mortality:
- mortality observed, treatment-related
- Body weight and weight changes:
- effects observed, treatment-related
- Food consumption and compound intake (if feeding study):
- no effects observed
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- no effects observed
- Haematological findings:
- no effects observed
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- not examined
- Gross pathological findings:
- no effects observed
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Histopathological findings: neoplastic:
- no effects observed
- Details on results:
- CLINICAL SIGNS AND MORTALITY
67% of control males and 76% of control females survived. Results for treatment groups were similar. Excess lacrimation was noticed in all groups, including controls, but was increased in 3000 ppm and 9016 ppm males.
BODY WEIGHT AND WEIGHT GAIN
There was a small dose related decrease (0.8-11.2%) in body weight gain in both sexes. This may have been due to reduced food consumption.
FOOD CONSUMPTION
There was decreased food consumption in treatment groups, however, there was no clear dose related response.
OPHTHALMOSCOPIC EXAMINATION
Some corneal dystrophy was seen, however, this is common in Fischer 344 rats and is not considered treatment related.
HAEMATOLOGY
No treatment related effects were noted.
GROSS PATHOLOGY
No macroscopic abnormalities related to treatment were observed.
HISTOPATHOLOGY:
Hyperplasia of the respiratory epithelium was seen most frequently in males and females exposed to 9000 ppm. The 3000 ppm and 9016 ppm groups had the most frequent hypertrophy/hyperplasia of goblet cells. This effect was more severe in exposure groups, and quite severe in the 9016 ppm group. These effects were likely due to mucosal irritation. Intracytoplasmic eosinophilic material in the respiratory epithelial cells, and sustentacular cells of the olfactory epithelium was seen in almost all animals in the exposure groups. This effect was most severe in the 3000 and 9016 ppm groups, but was also seen in the 900 ppm group. Inflammatory cells debris in the nasal lumen was also observed in most treatment groups, along with subacute /chronic inflammation of the nasal mucosa.
Squamous/squamoid metaplasia/hyperplasia of the pseudostratified columnar epithelium was seen in animals from both the control and exposure groups. Highest incidence was in the 9016 ppm group, followed by the 3000 ppm group. - Key result
- Dose descriptor:
- NOAEC
- Effect level:
- 9 016 ppm
- Sex:
- male/female
- Basis for effect level:
- other: Carcinogenicity
- Remarks on result:
- other: 31743 mg/m3
- Key result
- Dose descriptor:
- NOAEC
- Effect level:
- 9 016 ppm
- Sex:
- male/female
- Basis for effect level:
- other: Systemic Toxicity
- Key result
- Dose descriptor:
- LOAEC
- Effect level:
- 900 ppm
- Sex:
- male/female
- Basis for effect level:
- other: local toxicity (nasalturbinal tissue)
- Conclusions:
- There were no oncogenic effects in rats exposed to the test substance via inhalation at the maximum concentration tested, 9016 ppm (31736 mg/m3).
- Executive summary:
The purpose of this study was to determine the oncogenic effect of inhalation exposure of commercial hexane. Groups of 50 male and 50 female rats were exposed to 0, 900, 3000, or 9016 ppm of test substance for 6 hrs/day, 5 days/week, for 2 yrs. During the study, the animals were examined for clinical signs, mortality, body weight, opthomological, and food consumption effects. At study termination, animals were sacrificed and gross pathology and histopathology performed.
Mortalities of exposure groups were consistant with control groups. Body weight gain was significantly reduced in exposure groups. Histopathology revealed dose-related effects in the nasoturbinal tissue in all exposure groups. Therefore, there was no NOAEC level for local irritation effects. The LOAEC level for both sexes was 900 ppm. No oncogenic effects were seen in the exposure groups. The NOAEC for systemic effects was 9016 ppm in rats of both sexes.
- Endpoint:
- carcinogenicity: inhalation
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Study period:
- 1990-01-23 to 1992-01-20
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: This study is classified as reliable without restriction because it followed a protocol similar to OECD Guideline 451.
- 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
- Reason / purpose for cross-reference:
- reference to same study
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 451 (Carcinogenicity Studies)
- GLP compliance:
- yes (incl. QA statement)
- Species:
- mouse
- Strain:
- B6C3F1
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Portage, MI
- Age at study initiation: 8 weeks
- Weight at study initiation: approx. 24 g males, approx. 20 g females
- Housing: individually in stainless steel wire mesh cages, identified by tail tattoo
- Diet (e.g. ad libitum): Purina Certified Rodent Chow Brand Animal Diet #5002, ad libitum, except during exposure
- Water (e.g. ad libitum): Elizabethtown Water Company, ad libitum, except during exposure
- Acclimation period: 27 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23
- Humidity (%): 53 +/- 14
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark
IN-LIFE DATES: From: Jan. 23, 1990 To: Jan. 20, 1992 - Route of administration:
- inhalation: vapour
- Type of inhalation exposure (if applicable):
- whole body
- Vehicle:
- unchanged (no vehicle)
- Details on exposure:
- GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 10,000 l glass and stainless steel exposure chamber
- Method of holding animals in test chamber: individual cages
- Source and rate of air: chamber supplied air, 2000-2130 lpm
- Method of conditioning air: Test substance in a Protectoseal laboratory can passed through a fluid metering pump into teflon tubing to a coiled glass rod in the volatilization generator. Nitrogen was also fed into the volitization generator. A heating element was positioned in the center of the glass coil to aid volatilization. The nitrogen and test substance mixture then entered the exposure chamber.
- Air flow rate: 2000-2130 lpm
- Air change rate: 4.7-5.0 min.
- Method of particle size determination: TSI Aerodynamic Particle Sizer
- Treatment of exhaust air: Air was exhausted through a HEPA filter, charcoal filter, and into a MOCO incinerator. A charcoal drum was used as a back-up in case of incinerator failure.
TEST ATMOSPHERE
- Brief description of analytical method used: GC
- Samples taken from breathing zone: yes, monthly - Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Hourly samples were taken from the test chamber and analyzed using a MIRAN 1A Ambient Air Analyzer. In addition, samples were taken monthly and analyzed using GC.
- Duration of treatment / exposure:
- 2 yrs, total of 504 exposures
- Frequency of treatment:
- 6 hrs/day, 5 days/week
- Remarks:
- Doses / Concentrations:
0, 900, 3000, 9000 ppm
Basis:
other: target concentration - Remarks:
- Doses / Concentrations:
0.039, 900, 3000, 9018 ppm (0, 3168, 10560, 31680 mg/m3)
Basis:
analytical conc. - No. of animals per sex per dose:
- 50 per sex/per group
- Control animals:
- yes, sham-exposed
- Observations and examinations performed and frequency:
- CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations: mortality, toxicological and pharmacological signs
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: prior to test and weekly thereafter
BODY WEIGHT: Yes
- Time schedule for examinations: 3 times pretest, weekly for first 13 weeks, monthly thereafter
FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
2 times pretest, weekly for first 13 weeks, monthly thereafter
OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: pretest, termination
HAEMATOLOGY: Yes
- Time schedule for collection of blood: pretest, month 12, month 18, termination
- Anaesthetic used for blood collection: No
- Parameters checked: differential leucocyte counts - Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
nasal cavity, cranial cavity, brain, spinal cord, thoracic cavity, abdominal cavity, pelvic cavity, and neck
HISTOPATHOLOGY: Yes
lungs, abdominal aorta, adrenals, bone, bone marrow, brain, esophagus, exorbital lacrimal gland, eyes, gonads, gall bladder, heart, intestine, kidneys, larynx, liver, lymph nodes, nasopharyngeal tissues, nerves, pancreas, pituitary, prostate, salivary gland, seminal vesicles, skin, spinal cord, spleen, stomach, thymic region, thyroid, trachea, urinary bladder, uterus, gross lesions, tissue masses - Statistics:
- Body weight, body weight change, and mean food consumption were statistically analyzed.
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- effects observed, treatment-related
- Food consumption and compound intake (if feeding study):
- effects observed, treatment-related
- Food efficiency:
- not examined
- Water consumption and compound intake (if drinking water study):
- not examined
- Ophthalmological findings:
- no effects observed
- Haematological findings:
- no effects observed
- Clinical biochemistry findings:
- not examined
- Urinalysis findings:
- not examined
- Behaviour (functional findings):
- not examined
- Organ weight findings including organ / body weight ratios:
- not examined
- Gross pathological findings:
- effects observed, treatment-related
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Histopathological findings: neoplastic:
- effects observed, treatment-related
- Details on results:
- CLINICAL SIGNS AND MORTALITY
85% of control males and 80% of control females survived. Results for treatment groups were similar.
BODY WEIGHT AND WEIGHT GAIN
There were no statistically significant differences in body weight or body weight gains in male mice. Females in the 9018 ppm group had significantly reduced weight gain (14%).
FOOD CONSUMPTION AND COMPOUND INTAKE
The 9000 ppm group males had lower food consumption in 29 of 35 measurements. Food consumption was also lower then controls in the 9018 ppm females for 19 of the first 20 measurements.
OPHTHALMOSCOPIC EXAMINATION
No treatment related effects were seen.
HAEMATOLOGY
No treatment related effects were noted.
GROSS PATHOLOGY
Increases in liver masses and nodules were seen in 9018 ppm females. There was also a dose related increase in uterine cysts.
HISTOPATHOLOGY: NON-NEOPLASTIC
Females in the 9018 ppm group had a dose related decrease in the severity and incidence of cystic endometrial hyperplasia, and uterine cysts. There was also an increase in proliferative lesions of the pituitary in all female treatment groups, however, this did not seem to be dose related. These effects may have been due to hormonal imbalances due to treatment.
HISTOPATHOLOGY: NEOPLASTIC
There was a dose related increase in hepatocellular adenomas and carcinomas in females. There was a statistically significant increase in benign tumors, but not in malignant tumors. Incidence in 9018 ppm females was similar to control males. - Key result
- Dose descriptor:
- NOAEC
- Effect level:
- 9 018 ppm
- Sex:
- male
- Basis for effect level:
- other: Carcinogenicity
- Key result
- Dose descriptor:
- NOAEC
- Effect level:
- 3 000 ppm
- Sex:
- female
- Basis for effect level:
- other: Carcinogenicity
- Key result
- Dose descriptor:
- LOAEC
- Effect level:
- 9 018 ppm
- Sex:
- female
- Basis for effect level:
- other: Carcinogenicity
- Critical effects observed:
- not specified
- Conclusions:
- Liver tumors in B6C3F1 mice are known to be sensitive to body weight changes, especially in female B6C3F1 mice (NTP 2004). Therefore, the increased incidence of liver masses and nodules in female mice should be interpreted with care. The NOAEC level for oncogenic effects in female mice is 3000 ppm (10560 mg/m3). The LOAEC for female mice was 9018 ppm (31680 mg/m3). No oncogenic effects were seen in male mice. The NOAEC level for oncogenic effects in male mice is 9018 ppm (31680 mg/m3).
- Executive summary:
The purpose of this study was to determine the oncogenic effect of inhalation exposure of commercial hexane. Groups of 50 male and 50 female mice were exposed to 0, 900, 3000, or 9018 ppm (0, 3168, 10560, 31680 mg/m3) of test substance for 6 hrs/day, 5 days/week, for 2 yrs. During the study, the animals were examined for clinical signs, mortality, body weight, opthamological, and food consumption effects. At study termination, animals were sacrificed and gross pathology and histopathology performed.
Mortalities of exposure groups were consistant with control groups. Histopathology revealed increased liver masses and nodules in female mice at the 9018 ppm exposure group. Liver tumors in B6C3F1 mice are known to be sensitive to body weight changes, especially in female B6C3F1 mice (NTP 2004). Therefore, the increased incidence of liver masses and nodules in female mice should be interpreted with care. The NOAEC level for oncogenic effects in female mice is 3000 ppm (10560 mg/m3). The LOAEC for female mice was 9018 ppm (31680 mg/m3). No oncogenic effects were seen in male mice. The NOAEC level for oncogenic effects in male mice is 9018 ppm (31680 mg/m3).
NTP. 2004. NTP Technical Report on the Toxicology and Carcinogenesis Studies of Stoddard Solvent IIC (CAS No. 64742-88-7) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). NIH Publication No. 04-4453.
Referenceopen allclose all
Results of Rat Oncogenicity Study - Body Weights (g)
Dose |
Males - 13 Weeks |
Females - 13 Weeks |
Males - 105 Weeks |
Females - 105 Weeks |
0 |
290.2 |
179.4 |
345.8 |
250.6 |
900 ppm |
283.4 (-2.3%) |
174.4 (-2.8%) |
342.8 (-0.8%) |
250.7 (0%) |
3000 ppm |
281.3 (-3.1%) |
174.9 (-2.5%) |
327.3 (-5.3%) |
243.3 (-2.9%) |
9000 ppm |
279.3 (-3.8%) |
174.3 (-2.8%) |
321.3 (-7.1%) |
222.5 (-11.2%) |
Dose |
Kidney Inflammation |
Liver Hemorrhage |
Liver Inflammation |
Male |
|||
0 ppm |
2 |
0 |
0 |
900 ppm |
0 |
0 |
0 |
3000 ppm |
4 |
0 |
0 |
9000 ppm |
9 |
3 |
2 |
Female |
|||
0 ppm |
1 |
0 |
0 |
900 ppm |
Not examined |
Not examined |
Not examined |
3000 ppm |
Not examined |
Not examined |
Not examined |
9000 ppm |
1 |
0 |
0 |
Significant Results of Oncegenicity Study in Mice
0 ppm |
900 ppm |
3000 ppm |
9018 ppm |
|
Macroscopic Incidence of Uterine Cysts |
||||
No. Examined |
50 |
50 |
49 |
50 |
Uterine Cysts |
21 |
18 |
14 |
11 |
Liver Neoplasia Females |
||||
No. Examined |
50 |
50 |
49 |
50 |
Hepatocellular Adenomas |
4 |
6 |
4 |
10 |
Hepatocellular Carcinoma |
3 |
2 |
5 |
6 |
Total Neoplasms |
7 |
8 |
9 |
16 |
Liver Neoplasia Males |
||||
No. Examined |
49 |
50 |
50 |
50 |
Hepatocellular Adenomas |
10 |
5 |
7 |
10 |
Hepatocellular Carcinoma |
7 |
11 |
10 |
3 |
Total Neoplasms |
17 |
16 |
17 |
13 |
Incidence of Cystic Endometrial Hyperplasia |
||||
No. Examined |
50 |
32 |
32 |
50 |
No. of Incidences |
48 |
29 |
27 |
44 |
Trace |
3 |
4 |
3 |
10 |
Mild |
14 |
13 |
8 |
19 |
Moderate |
23 |
10 |
15 |
15 |
Severe |
8 |
2 |
1 |
0 |
Pituitary Proliferative Lesions in Females |
||||
No. Examined |
45 |
48 |
48 |
49 |
Hyperplasia |
2 |
4 |
4 |
6 |
Adenoma |
0 |
6 |
7 |
5 |
Adenocarcinoma |
0 |
0 |
1 |
0 |
Total Neoplasms |
0 |
6 |
8 |
5 |
Total Proliferative Lesions |
2 |
10 |
12 |
11 |
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEC
- 31 680 mg/m³
- Study duration:
- chronic
- Species:
- mouse
- Quality of whole database:
- Two key read across studies from a structural analogue available for assessment
Carcinogenicity: via dermal route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Justification for classification or non-classification
Based on available read across data, 2,3-Dimethylbutane is not classified as carcinogenic under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).
Additional information
No standard carcinogenicity studies are available for 2,3-Dimethylbutane. However, data is available for structural analogue, 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.
Commercial hexane
In a two-part study, the oncogenic effects of inhalation exposure to commercial hexane (52% n-hexane) were evaluated in male and female mice and male and female rats (Daughtrey, 1999; Klimisch score = 1). In Part I of the study groups of 50 male and 50 female rats were exposed to 0, 900, 3000, or 9016 ppm of test substance for 6 hrs/day, 5 days/week, for 2 yrs. Mortalities of exposure groups were consistent with control groups. Body weight gain was significantly reduced in exposure groups. Histopathology revealed dose-related irritation-related effects in the nasoturbinal tissue in all exposure groups. Therefore, there was no NOAEC level for local irritation effects. The LOAEC level for both sexes was 900 ppm for irritation. No oncogenic effects were seen in the exposure groups. The NOAEC for systemic effects was 9016 ppm in rats of both sexes.
In Part II of the study, groups of 50 male and 50 female mice were exposed to 0, 900, 3000, or 9018 ppm (0, 3168, 10560, 31680 mg/m3) of commercial hexane (52% n-hexane) for 6 hrs/day, 5 days/week, for 2 yrs. Mortalities of exposure groups were consistent with control groups. Histopathology revealed increased liver masses and nodules in female mice at the 9018 ppm exposure group. As referenced by the National Toxicology Program, liver tumours in B6C3F1 mice are known to be sensitive to body weight changes, especially in female B6C3F1 mice. Therefore, the increased incidence of liver masses and nodules in female mice are deemed of questionable relevance for human health risk assessment. Therefore, the NOAEC level for oncogenic effects in mice is 9018 ppm (31680 mg/m3).
This study directly informs the DNEL.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
![ECHA](/o/diss-blank-theme/images/factsheets/A-REACH/factsheet/echa_logo.png)