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EC number: 203-806-2 | CAS number: 110-82-7
- 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
Endpoint summary
Administrative data
Description of key information
Cyclohexane is of low acute toxicity by the oral (LC50 >5,000 mg/kg), inhalation (4 h LC50 >32,880 mg/m3) or dermal (LD50 >2,000 mg/kg) routes.
Key value for chemical safety assessment
Acute toxicity: via oral route
Link to relevant study records
- Endpoint:
- acute toxicity: oral
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: GLP status unknown, near guideline study, available as unpublished report, restrictions in design and/or reporting but otherwise adequate for assessment
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 401 (Acute Oral Toxicity)
- GLP compliance:
- not specified
- Test type:
- standard acute method
- Limit test:
- yes
- Species:
- rat
- Strain:
- not specified
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- Not reported
- Route of administration:
- oral: unspecified
- Vehicle:
- not specified
- Details on oral exposure:
- Not reported
- Doses:
- 5000 mg/kg bodyweight
- No. of animals per sex per dose:
- 5
- Control animals:
- no
- Sex:
- male/female
- Dose descriptor:
- LD50
- Effect level:
- > 5 000 mg/kg bw
- Remarks on result:
- other: no mortalities
- Mortality:
- No mortalities
- Clinical signs:
- other: Depression, slight depression, salivation and soft faeces were seen 1 hour after dosing until day 1. All animals appeared normal by day 2.
- Gross pathology:
- No abnormalities.
- Interpretation of results:
- practically nontoxic
- Remarks:
- Migrated information Criteria used for interpretation of results: EU
- Conclusions:
- The acute oral LD50 of cyclohexane to male and female rats was in excess of 5000 mg/kg bodyweight.
- Executive summary:
The acute oral LD50 of cyclohexane to male and female rats was in excess of 5000 mg/kg bodyweight.
Reference
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LD50
- Value:
- 5 000 mg/kg bw
- Quality of whole database:
- Studies in rats demonstrate that the oral LD50 for cyclohexane is greater than 5000 mg/kg bw.
Acute toxicity: via inhalation route
Link to relevant study records
- Endpoint:
- acute toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Non GLP, near guideline study, available as unpublished report, restrictions in design and/or reporting but otherwise adequate for assessment
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 403 (Acute Inhalation Toxicity)
- GLP compliance:
- no
- Test type:
- standard acute method
- Limit test:
- yes
- Species:
- rat
- Strain:
- not specified
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- No details reported
- Route of administration:
- inhalation: vapour
- Type of inhalation exposure:
- whole body
- Vehicle:
- other: air
- Details on inhalation exposure:
- No details reported
- Analytical verification of test atmosphere concentrations:
- yes
- Duration of exposure:
- 4 h
- Concentrations:
- Nominal concentration 32.88 mg/L (9570.43 ppm)
Mean analytical concentration 21250.0±925.82 ppm - 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 recorded once per hour during exposure and once per day thereafter. Bodyweights recorded pre-exposure and on days 2, 3, 4, 7 and 14 post-exposure.
- Necropsy of survivors performed: yes - Statistics:
- Not required, limit dose
- Sex:
- male/female
- Dose descriptor:
- LC50
- Effect level:
- > 32 880 mg/m³ air
- Exp. duration:
- 4 h
- Remarks on result:
- other: no mortalities
- Mortality:
- No mortalities
- Clinical signs:
- other: During exposure, observations in males and females included tremors, hyperactivity, rapid respiration and lying prostrate in cage. During the post-exposure period all females appeared normal, one male had localised alopecia up to day 10 and sores around t
- Body weight:
- No exposure-related effects
- Gross pathology:
- No exposure-related effects
- Interpretation of results:
- not classified
- Remarks:
- Migrated information Criteria used for interpretation of results: EU
- Conclusions:
- The acute inhalation LC50 of cyclohexane to male and female rats, following a 4 hour exposure, was >32.88 mg/L.
- Executive summary:
The acute inhalation LC50 of cyclohexane to male and female rats, following a 4 hour exposure, was >32.88 mg/L.
Reference
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LC50
- Value:
- 32 880 mg/m³ air
- Quality of whole database:
- Studies in rats demonstrate that the inhalation LC50 for cyclohexane exceeds 32,880 mg/m3.
Acute toxicity: via dermal route
Link to relevant study records
- Endpoint:
- acute toxicity: dermal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: GLP status unknown, near guideline study, available as unpublished report, restrictions in design and/or reporting but otherwise adequate for assessment
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 402 (Acute Dermal Toxicity)
- GLP compliance:
- not specified
- Test type:
- standard acute method
- Limit test:
- yes
- Species:
- rabbit
- Strain:
- not specified
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- No details reported
- Type of coverage:
- not specified
- Vehicle:
- not specified
- Duration of exposure:
- Not reported
- Doses:
- 2000 mg/kg
- No. of animals per sex per dose:
- 3
- Control animals:
- no
- Details on study design:
- Animals were observed 1, 2 and 4 hours on the day of application and daily thereafter for a further 14 days.
- Sex:
- male/female
- Dose descriptor:
- LD50
- Effect level:
- > 2 000 mg/kg bw
- Remarks on result:
- other: no mortalities
- Mortality:
- No mortalities.
- Clinical signs:
- other: All rabbits vocalised as test substance applied. No other clinical observations observed.
- Gross pathology:
- No abnormalities.
- Other findings:
- Dermal irritation: Erythema on day 1 ranged from very slight in 2 males to well-defined in 1 female. On day 3 erythema was very slight in 2 males and 2 females but had cleared by day 7. Oedema on day 1 ranged from very slight in 1 male and 3 females to slight in 1 male but had cleared by day 3. Scaling was present in 1 female on day 10.
- Interpretation of results:
- practically nontoxic
- Remarks:
- Migrated information Criteria used for interpretation of results: EU
- Conclusions:
- Acute dermal LD50 of cyclohexane to male and female rabbits was in excess of 2000 mg/kg bodyweight.
- Executive summary:
Acute dermal LD50 of cyclohexane to male and female rabbits was in excess of 2000 mg/kg bodyweight.
Reference
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LD50
- Value:
- 2 000 mg/kg bw
- Quality of whole database:
- Studies in rats demonstrate that the dermal LD50 for cyclohexane exceeds 2000 mg/kg bw.
Additional information
The acute toxicity of cyclohexane was reviewed and reported in the EC RAR (2004). No additional relevant data has been sourced in the updated literature search.
Non-human information
Acute toxicity: oral
An oral LD50 value in rats of >5,000 mg/kg is derived from what is considered to be the key study (HLA, 1982a) as the most recent with the lowest LD50 value reported.
As summarised in the RAR (2004), Kimura et al (1971) reported oral LD50 values ranging from 8,000-39,000 mg/kg, dependent on the age of the animal with symptoms of toxicity including a depressive effect on the central nervous system, salivation and soft faeces. Deichmann and Le Blanc (1943) reported an LD50 value of 29,800 mg/kg. In rabbits the lowest lethal dose was found to be 6 g/kg (Treon et al., 1943a) with symptoms including severe diarrhoea, weight loss and increased respiration rate. The authors reported no evidence of acute involvement of the central nervous system (narcosis or convulsions).
Acute toxicity: inhalation
A 4-hour exposure LC50 on rats of > 9,500 ppm (32,880 mg/m3) reported by HLA (1982b) and this is considered to be the key study as it is the most recent study and has the guideline exposure period. No death occurred at this concentration with symptoms noted during the exposure being tremors, hyperactivity, rapid respiration and hypoactivity. The acute neurotoxicity of cyclohexane is discussed under the relevant section of the submission.
Also cited in the RAR (2004) is a Treon et al. (1943b) publication reporting acute inhalation exposure of rabbits. A 1 hour exposure produced effects on the central nervous system, with exposure-related observations including convulsions, tremors, hyperactivity, rapid respiration, cyanosis and diarrhoea. All the animals exposed to 26,000 ppm (89.6 mg/L) died
Acute toxicity: dermal
An acute dermal toxicity test is available on cyclohexane in rabbits (HLA, 1982d) and this is considered to be the key study. The LD50 was estimated to be greater than 2,000 mg/kg with no deaths or systemic symptoms observed. In a few animals slight erythema and oedema were noted.
Acute toxicity: other routes
This information is not available.
Human information
Acute neurotoxicity data is available and reported under the relevant sections of the dossier. The NOAEC in a human volunteer study (Lammers et al, 2009) was 250 ppm (860 mg/m3).
Summary and discussion of acute toxicity
Although the RAR (2004) reports that most of the LD50 studies are old and performed without GLP information, the protocols and results were correctly described and it was concluded that they should be considered reliable.
Justification for selection of acute toxicity – oral endpoint
The acute oral LD50 of cyclohexane in male and female rats is greater than 5000 mg/kg bw.
Justification for selection of acute toxicity – inhalation endpoint
The acute inhalation LC50 of cyclohexane exceeds 9,500 ppm (32,880 mg/m3).
Justification for selection of acute toxicity – dermal endpoint
The acute dermal LD50 of cyclohexane in male and female rats is greater than 2000 mg/kg bw.
Justification for classification or non-classification
The applicant submits that cyclohexane is of low acute toxicity by the oral, inhalation or dermal routes with LD50/LC50 values exceeding the doses which would warrant classification under CLP.
The low viscosity of cyclohexane (kinematic viscosity of 1.259.10-6 m2/s and a surface tension of 25.3 mN/m at 20°C) justifies classification under CLP, Aspiration toxicity Category 1 assigned H304.
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