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Diss Factsheets
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EC number: 222-389-8 | CAS number: 3457-61-2
- 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)
Endpoint summary
Administrative data
Link to relevant study record(s)
- Endpoint:
- basic toxicokinetics, other
- Remarks:
- G.I. human passive absorption
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
- Objective of study:
- absorption
- Guideline:
- other: REACH Guidance on QSARs R.6
- Principles of method if other than guideline:
- Model to predict either high or low fraction absorbed for an orally administered, passively transported substance on the basis of a new absorption parameter. The model includes only two inputs: the octanol-water partition coefficient (Kow) and the dimensionless oversaturation number (OLumen). The latter is the ratio of the concentration of drug delivered to the gastro-intestinal (GI) fluid to the solubility of the compound in that environment.
- Species:
- other: Human
- Route of administration:
- oral: unspecified
- Type:
- absorption
- Results:
- Absorption from gastrointestinal tract for 1 mg dose: 100%
- Type:
- absorption
- Results:
- Absorption from gastrointestinal tract for 1000 mg dose: 90%
- Endpoint:
- dermal absorption, other
- Remarks:
- QSAR
- Type of information:
- (Q)SAR
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- results derived from a (Q)SAR model, with limited documentation / justification, but validity of model and reliability of prediction considered adequate based on a generally acknowledged source
- Guideline:
- other: REACH Guidance on QSARs R.6
- Principles of method if other than guideline:
- IH SkinPerm (v2.0) is a mathematical tool for estimating dermal absorption. The rate of mass build-up (or loss) on the skin comes from the deposition rate onto the skin minus the absorption rate into the Stratum Corneum (SC) and the amount evaporating from the skin to the air.
- Species:
- other: human
- Type of coverage:
- open
- Vehicle:
- unchanged (no vehicle)
- Details on study design:
- DATA INPUT
Molecular weight: 208.3 g/mol
Temperature: 25 °C
Vapour Pressure: 3 Pa (Epiwin)
Water solubility: 10.7 mg/L
Log Kow: 4.47
Density: 963.2 mg/cm3
Melting point: 11.3°C
SCENARIO PARAMETERS
- Instantaneous deposition
Deposition dose*: 4493 mg (4.8 mL * density mg/cm3)
Affected skin area**: 1000 cm²
Maximum skin adherence***: 2 mg/cm²
Thickness of stagnant air****: 1 cm
Weight fraction: 1
Timing parameters
. Start deposition: 0 hr
. End time observation: 8 hr
Report parameters
. Calculation (intervals/hr): 10000
. Report (intervals/hr): 100
- Deposition over time
Affected skin area**: 1000 cm²
Maximum skin adherence***: -1 mg/cm²
Dermal deposition rate: 2 mg/cm²/hr
Thickness of stagnant air****: 1 cm
Weight fraction: 1
Timing parameters
. Start deposition: 0 hr
. Duration of deposition: 8hr
. End time observation: 8 hr and 24 hr
Report parameters
. Calculation (intervals/hr): 10000
. Report (intervals/hr): 100
*Approximately 2 mL of a liquid having a viscosity similar to water will practically wet the palms of two hands (420 cm2). So ca. 4.8 mL will wet all the skin surface of both hands. It is reasonably expected more liquid will be excess and wash/fall off.)
**Estimated skin surface of two hands of an adult.
***The skin adherence field is greyed out and a default of -1 is indicated if the substance is a liquid at 25°C. Smart logic is built into IH SkinPerm; the program recognizes whether a substance is a solid or liquid at standard temperature (25°C) based on the physicochemical properties. For substances
that are solids at 25°C a maximum adherence value up to 2 mg/cm² is allowed based on studies of soil-on-skin adherence. If the deposition rate results in an increase above the input figure (0.2-2 mg/cm²), it is assumed that the surplus disappears just by removal from the skin.
*** 3 cm if clothing involved, 1 cm if bare skin involved - Time point:
- 8 h
- Dose:
- 4493 mg/1000cm²/8hr
- Parameter:
- percentage
- Absorption:
- 0.61 %
- Remarks on result:
- other: Instantaneous deposition
- Time point:
- 8 h
- Dose:
- 1 mg/cm²/h
- Parameter:
- percentage
- Absorption:
- 0.34 %
- Remarks on result:
- other: Deposition over time for 8 hr
- Time point:
- 24 h
- Dose:
- 1 mg/cm²/h
- Parameter:
- percentage
- Absorption:
- 1.03 %
- Remarks on result:
- other: Deposition over time for 8 hr
- Conclusions:
- The dermal absorption of tert-butyl 1-methyl-1-phenylethyl peroxide is estimated to be loiw (<= 1%).
- Executive summary:
The dermal absorption of tert-butyl 1-methyl-1-phenylethyl peroxide leads to the following results, obtained using the SkinPerm v2.0 model according to the input data:
Instantaneous deposition
Deposition over time
End time observation 8 hr
Deposition over time
End time observation 24hr
Total deposition (mg)
4490
8000
8000
Fraction absorbed (%)
0.611
0.343
1.03
Amount absorbed (mg)
27.5
27.5
82.4
Lag time stratum corneum (min)
6.97
6.97
6.97
Max. derm. abs. (mg/cm²/h)
0.00172
0.00172
0.00172
Referenceopen allclose all
Description of key information
No data on toxicokinetics, metabolism and distribution are available for tert-butyl a,a-dimethylbenzyl peroxide (TBCP).
Absorption
The assessment of the toxicokinetics of TBCP is based on the available toxicological data and its physicochemical properties as suggested by the REACH Guidance Chapter R.7c.
TBCP is a colourless liquid with a molecular weight of 208.3 g/mol. The substance is only slightly soluble in water (10.7 mg/L). The measured log Kow is 4.4. The vapour pressure is relatively low: 14 Pa at 40 °C. TBCP is considered to be potentially bioaccumulate in body, regarding the calculated BCF of 794.
TBCP is not degraded hydrolytically at pH 4, 7 and 9. At pH 1.2, TBCP is hydrolysed, with a half-life time of 6.7 hours. Only 2-phenyl 2 -propanol has been shown to be a by-product of hydrolysis.
Dermal absorption
Based on physico–chemical properties, TBCP is not likely to penetrate skin to a large extent as the high log Kow value and the low water solubility do not favour dermal penetration. Water solubility of 1-100 mg/l is in favour of a low to moderate dermal absorption. For substances with a log Kow between 4 and 6, the rate of penetration is limited by the rate of transfer between the stratum corneum and the epidermis. Only the uptake into the stratum corneum will be high. Nevertheless, application of TBCP to skin of rabbits causes irritation, which could increase the dermal uptake.
The rate of absorption was estimated using the IH SkinPerm model (v2.0) and leads to the following results according to the input data:
|
Instantaneous deposition |
Deposition over time End time observation 8 hr |
Deposition over time End time observation 24hr |
Total deposition (mg) |
4490 |
8000 |
8000 |
Fraction absorbed (%) |
0.611 |
0.343 |
1.03 |
Amount absorbed (mg) |
27.5 |
27.5 |
82.4 |
Lag time stratum corneum (min) |
6.97 |
6.97 |
6.97 |
Max. derm. abs. (mg/cm²/h) |
0.00172 |
0.00172 |
0.00172 |
The rate of absorption is estimated to be low (<= 1%). Therefore, according to the REACH guidance R7c (2017) a default value of 10% skin absorption is chosen. However, the substance is a skin irritant Cat. 2. Therefore, the dermal absorption is assumed to be 20%.
Oral absorption
Oral absorption is favoured for molecular weights below 500 g/mol. Based on the high log Kow of 4.4 TBCP can be regarded as lipophilic substance. Such a lipophilic compound may be taken up by micellular solubilisation. This mechanism may be of particular importance for TBCP as the substance is only slightly soluble and would otherwise be poorly absorbed. TBCP showed toxic effects at dose level of 600 mg/kg bw/day in repeated dose and reproduction toxicity studies when administered in corn oil, whereas administered in an acute study lead to a high LD0 ( > 2000 mg/kg). Therefore it can be assumed that significant absorption across the gastrointestinal tract epithelium will occur when administered in repeated dosages. Using a model to predict either high or low fraction absorbed for an orally administered, passively transported substance, the rates of absorption were 100 and 90% for a dose of 1 and 1000 mg, respectively.
As hydrolysis occurs at pH 1.2 (human gastric pH), whereas it does not occur at pH 4 (rat gastric pH), there may be differences between rats and humans for oral toxicity, since at pH 1.2, humans will be partly exposed to hydrolysis byproducts. Nevertheless, regarding the half-life time (6.7 h) and the water solubility (10.7 mg/L), these differences should remain relatively negligible. The oral aborption rate is assumed to be 100%.
Inhalation exposure
Based on the low vapour pressure of 14 Pa at 40 °C, inhalation exposure is less likely than oral absorption. Nevertheless, if the substance reaches the lung, TBCP may be absorbed by micellular solubilisation (see above). The low water solubility may enhance penetration to the lower respiratory tract.
Therefore, according to the REACH Guidance, default values of 100, 20 and 100% will be used for oral, dermal and inhalation absorptions, respectively.
Key value for chemical safety assessment
- Absorption rate - oral (%):
- 100
- Absorption rate - dermal (%):
- 20
- Absorption rate - inhalation (%):
- 100
Additional information
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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