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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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
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EC number: 203-631-1 | CAS number: 108-94-1
- 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)
Toxicological Summary
- Administrative data
- Workers - Hazard via inhalation route
- Workers - Hazard via dermal route
- Workers - Hazard for the eyes
- Additional information - workers
- General Population - Hazard via inhalation route
- General Population - Hazard via dermal route
- General Population - Hazard via oral route
- General Population - Hazard for the eyes
- Additional information - General Population
Administrative data
Workers - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 10 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- By inhalation
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 20
- Dose descriptor starting point:
- NOAEC
- Value:
- 408 mg/m³
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 204 mg/m³
- Explanation for the modification of the dose descriptor starting point:
Corrected for 8 h exposure, as proposed in the REACH Guidance (R.8.4.2)
Correction for activity driven differences of respiratory volumes in workers compared to workers in rest (6.7 m3/10 m3).
NOAEC corrected inhalative= 408 * (6/8) * (6.7/10) =204 mg/m3
- AF for dose response relationship:
- 1
- Justification:
- Default factor if a NOAEL is used as starting point.
- AF for differences in duration of exposure:
- 2
- Justification:
- Use of a subchronic study as starting point for long-term systemic DNEL derivation (default assessment factor according to R8 ECHA 2012).
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- Allometric scaling already considered during modification of the starting point.
- AF for other interspecies differences:
- 2
- Justification:
- The default factor of 2.5 is reduced to 2 as the setting of the NOAEL in the 90-day inhalation study is based on a conservative approach and arguable (see endpoint summary for repeated dose toxicity).
- AF for intraspecies differences:
- 5
- Justification:
- Default factor for the worker
- AF for the quality of the whole database:
- 1
- Justification:
- Different inhalation studies in two species available.
- AF for remaining uncertainties:
- 1
- Justification:
- No remaining uncertainties.
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 20 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- By inhalation
DNEL related information
- DNEL extrapolated from long term DNEL
- Dose descriptor starting point:
- NOAEC
- Value:
- 408 mg/m³
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 204 mg/m³
Local effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 10 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 20 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- DNEL extrapolated from long term DNEL
Workers - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 4 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 25
- Modified dose descriptor starting point:
- NOAEL
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 4 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 25
- Modified dose descriptor starting point:
- NOAEL
Local effects
Long term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Workers - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Additional information - workers
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 2.55 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- By inhalation
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 40
- Dose descriptor starting point:
- NOAEL
- Value:
- 408 mg/m³
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 102 mg/m³
- Explanation for the modification of the dose descriptor starting point:
Corrected for 24 h exposure, as proposed in the REACH Guidance (R.8.4.2)
NOAEC corrected inhalative= 408 * (6/24) = 102 mg/m3
- AF for dose response relationship:
- 1
- Justification:
- Default factor if a NOAEL is used as starting point.
- AF for differences in duration of exposure:
- 2
- Justification:
- Use of a subchronic study as starting point for long-term systemic DNEL derivation (default assessment factor according to R8 ECHA 2012).
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- Allometric scaling not necessary (NOAEL from inhalation study).
- AF for other interspecies differences:
- 2
- Justification:
- The default factor of 2.5 is reduced to 2 as the setting of the NOAEL in the 90-day inhalation study is based on a conservative approach and arguable (see endpoint summary for repeated dose toxicity).
- AF for intraspecies differences:
- 10
- Justification:
- Default factor for the general population
- AF for the quality of the whole database:
- 1
- Justification:
- Different inhalation studies in two species available.
- AF for remaining uncertainties:
- 1
- Justification:
- No remaining uncertainties.
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 5 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- By inhalation
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- DNEL extrapolated from long term DNEL
Local effects
Long term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
DNEL related information
General Population - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 1 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 100
- Modified dose descriptor starting point:
- NOAEL
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 1 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 100
- Modified dose descriptor starting point:
- NOAEL
Local effects
Long term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
General Population - Hazard via oral route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 1.5 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 100
- Modified dose descriptor starting point:
- NOAEL
Acute/short term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 1.5 mg/kg bw/day
- Most sensitive endpoint:
- repeated dose toxicity
DNEL related information
- Overall assessment factor (AF):
- 100
- Modified dose descriptor starting point:
- NOAEL
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Additional information - General Population
For the systemic DNELs concerning dermal and inhalation exposure the rationales are presented above.
Concerning oral short-term and long-term exposures, the DNELs are based upon the NOAEL (143 mg/kg bw/d) in the BASF subchronic drinking water study. The chronic drinking water studies which are also available do not show a decrease of the NOAEL with exposure time. Furthermore, in the course of the intravenous studies, no significant difference was seen between single administration and repeated administration; the effects observed were reversible within 30 min. Hence, the time extrapolation factor can be fixed to 1. In the light of known qualitative differences in the metabolic profiles between rodents and humans (Mraz et al., loc.cit.) a default factor of 2.5 is proposed in addition to the allometric factor of 4. (This does not necessarily mean that humans are more sensitive.) The interindividual variability towards Cyclohexanone appears to be low in the species investigated and also in human adults; however, children may be more sensitive and therefore an interspecies factor of 10 is proposed, which leads to an overall factor of 100 and oral DNELs of 1.5 mg/kg bw (acute and chronic).
For the inhalation DNELs, the calculation procedure is similar as for the workplace. However, in terms of systemic toxicity a 4 -fold higher intraspecies variability was taken into account and led to a total intraspecies factor of 10.
Similarly, also the dermal DNELs for the workplace (derived from the subacute infusion study in rats with a NOAEL of 100 mg/kg/d; see above) were divided by 4.
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.
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