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EC number: 218-507-2 | CAS number: 2167-23-9
- 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
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:
- 2.65 mg/m³
- Most sensitive endpoint:
- repeated dose toxicity
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 50
- Dose descriptor starting point:
- NOAEL
- Value:
- 150 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEC
- Value:
- 132.237 mg/m³
- Explanation for the modification of the dose descriptor starting point:
The NOAEL of 150 mg/kg bw/d from an OECD 422 repeat dose oral gavage study in rats was used (males 42 days and females 56 days). assuming an oral/inhalation absorption of 0.5, a dose descriptor of 132.2368 mg/m3 was derived as the starting point.
- AF for dose response relationship:
- 1
- Justification:
- Based on REACH guidance
- AF for differences in duration of exposure:
- 4
- Justification:
- Based on REACH guidance
- AF for other interspecies differences:
- 2.5
- Justification:
- Based on REACH guidance
- AF for intraspecies differences:
- 5
- Justification:
- Based on REACH guidance
- AF for the quality of the whole database:
- 1
- Justification:
- Based on REACH guidance
- AF for remaining uncertainties:
- 1
- Justification:
- Based on REACH guidance
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Workers - Hazard via dermal 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
- Route of original study:
- Oral
DNEL related information
- DNEL derivation method:
- ECHA REACH Guidance
- Overall assessment factor (AF):
- 200
- Dose descriptor starting point:
- NOAEL
- Value:
- 150 mg/kg bw/day
- Modified dose descriptor starting point:
- NOAEL
- Value:
- 300 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
The NOAEL of 150 mg/kg bw/d from an OECD 422 repeat dose oral gavage study in rats was used (males 42 days and females 56 days). Assuming an oral/dermal absorption of 50%, a dose descriptor of 300 mg/kg bw/d was derived as the starting point. A 50% dermal absorption was based on the molecular weight of 234.3 g/mol, log Pow of 5.4 at 300C, water solubility of 8.3 mg/L at 200C.
- AF for dose response relationship:
- 1
- Justification:
- Based on REACH guidance
- AF for differences in duration of exposure:
- 4
- Justification:
- Correction for the duration of subchronic (6 weeks) to chronic (13 weeks); Based on REACH guidance
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- Based on REACH guidance
- AF for other interspecies differences:
- 2.5
- Justification:
- Additional factors (Based on REACH guidance)
- AF for intraspecies differences:
- 5
- Justification:
- Based on REACH guidance
- AF for the quality of the whole database:
- 1
- Justification:
- Based on REACH guidance
- AF for remaining uncertainties:
- 1
- Justification:
- Based on REACH guidance
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
Workers - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- no hazard identified
Additional information - workers
Correction of dose descriptors for route-to-route extrapolation, application of assessment factors and derivation of the endpoint specific DNEL
Phys-Chem data considered for the calculation of DNEL for CAS 2167-23-9 were:
Endpoint CAS Number 2167-23-9:
MW 234.3 g/mol,
Appearance Liquid
Water solubility 8.3 mg/L at 200C (measured)
Log Pow 5.4 (measured)
VP 15 Pa at 25oC (measured)
Skin irritation Mild irritant, but not classifiable
Skin Sensitization No
Initial Dose Descriptor
In a OECD 422 oral gavage reproductive toxicity screening study with rats, a no-observed-adverse-effect-level (NOAEL) of 150 mg/kg/day was established for the systemic toxic effects of 2,2-di(ter-butylperoxy) butane (CAS # 2167-23-9) in males and females. Treatment-related microscopic findings noted in the liver, and thyroid in females were noted at 500 mg/kg/d but were considered to be adaptive changes. Therefore, 150 mg/kg/d was considered to be the no-observed-adverse-effect-level (NOAEL) in females. The microscopic findings in the male kidney (tubular basophilia and proteinaceous casts) were considered to be associated with alpha 2u-globulin and formation of hyaline droplets, an effect recognized as being both species specific and sex specific and not relevant for humans. (Alden, CL and Frith CH. Urinary System, Ch. 15, pp 315-387. In: Handbook of Toxicologic Pathology Eds. Haschek WM and Rousseaux CG. Academic Press, San Diego. 1991). A range of chemicals are known to increase hyaline droplet formation beyond the physiological capacity of the tubular epithelium which may then result in tubular epithelial cell damage (hyaline droplet nephropathy) which was evident in this study. The NOAEL for males was therefore considered to be 150 mg/kg/day. The no-observed-effect-level (NOEL) was 50 mg/kg/d for either sex and the NOEL for reproductive toxicity was considered to be 500 mg/kg/d.
In summary, based on the entire study findings, the systemic NOAEL for DNEL calculations was set a 150 mg/kg/day.
Due to low vapor pressure, inhalation is not expected to be a major route of exposure. For the DNEL covering local effects of inhalation or dermal routes of exposure, route-specific data need to be available (Guidance on information requirements and chemical safety assessment R 8.1.2.6). Exposure to a repeated oral high dose is not expected under normal occupational settings and there are no consumer uses of this substance. Human exposure, via the environment, is unlikely due to the instability of the peroxide. DNELs were derived for systemic long term effects for inhalation and dermal routes.
DNEL dermal-systemic-worker
The NOAEL of 150 mg/kg/day was selected from an OECD 422 repeat dose oral study in rats. Oral absorption rat – oral/dermal absorption human: Assume 50% absorption based on the physical-chemical properties (low water solubility, higher log Kow, low molecular weight) in accordance with Endpoint Specific Guidance Chapter 8 and 7c (R.7.12). Therefore, a dose descriptor of 300 mg/kg/day was derived as the starting point. See discussion for route to route extrapolation calculations.
DNEL dermal-systemic-worker:
150 mg/kg/day / 0.5 = 300 mg/kg/day = dermal dose descriptor
Applying assessment factors in accordance with Endpoint Specific Guidance Chapter 8:
Correction for interspecies differences (apply factor for allometric scaling 4 for rat x 2.5 for additional factors): 10. Therefore, 300 mg/kg/day/10 = 30 mg/kg/day
Correction for intraspecies difference: 5
30 mg/kg/day/5 = 6 mg/kg/day
Correction for duration between sub-chronic (6 weeks) to chronic: 4
6 mg/kg/day/4 = 1.5 mg/kg/day
Correction for dose-response: 1 due to NOAEL
1.5 mg/kg/day/1 = 1.5 mg/kg/day
Correction for whole database: 1 due to quality of study
1.5 mg/kg/day/1 = 1.5 mg/kg/day
Total AF = 200
1.5 mg/kg/day DNEL dermal-worker-systemic
DNEL inhalation-systemic-worker:
The dose descriptor of 150 mg/kg/day was selected from an OECD 422 repeat dose oral study in rats.
Assume ABSoral-rat/ABSinh-human is 50/100 = 0.5 based on physical-chemical properties and Endpoint Specific Guidance chapters 8 and 7c (R.7.12)
Corrected inhalatory NOAEC from oral NOAEL:
Oral NOAEL x (1/sRVrat) x (ABSoral-rat/ABSinh-human) x (sRVhuman/wRV)[ABS: absorption; sRV: standard Respiratory Volume; wRV: worker Respiratory Volume]
Corrected NOAEC = 150 mg/kg/day x (1/0.38 m3/kg/day) x (0.5) x 6.7m3/10m3 =132.2368 mg/m3 = inhalation dose descriptor.
Applying remaining assessment factors in accordance with Endpoint Specific Guidance Chapter 8:
Correction for interspecies differences: 2.5
132.2368 mg/m3/2.5 = 52.89474 mg/m3
Correction for intraspecies difference: 5
52.89474 mg/m3/5 = 10.57895 mg/m3
Correction for duration between sub-chronic to chronic: 4
10.57895 mg/m3/4 = 2.644737 mg/m3
Correction for dose-response: 1
2.644737 mg/m3/1 = 2.644737 mg/m3
Correction for whole database: 1 due to quality of study
2.644737 mg/m3/1 = 2.644737 mg/m3
Total AF = 50
2.65 mg/m3DNEL inhalation-systemic-worker
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
- Explanation for the modification of the dose descriptor starting point:
No exposure to the general population is anticipated for this route of exposure.
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
- Explanation for the modification of the dose descriptor starting point:
No exposure to the general population is anticipated for this route of exposure.
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
General Population - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
Local effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
General Population - Hazard via oral route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- no hazard identified
Acute/short term exposure
- Hazard assessment conclusion:
- no hazard identified
DNEL related information
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- no hazard identified
Additional information - General Population
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