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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: 202-653-9 | CAS number: 98-29-3
- 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:
- 1.48 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):
- 75
- Dose descriptor starting point:
- LOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- LOAEC
- Value:
- 111.1 mg/m³
- Explanation for the modification of the dose descriptor starting point:
The starting point is converted using an oral-to-inhalation route extrapolation, assuming 90%* absorption for oral route and 100% absorption for inhalation and using standard respiratory volumes of 0.38 m3/kg over 8 hours for rats, 6.7 m3/person over 8 hours and 10 m3/person over 24 hours for humans):
LOAEC worker (8 h)= 70 x (1 / 0.38) x (6.7 / 10) x (90/100) = 111.1 mg/m3
* According to US NTP (2002) study (oral route, rats), approximately 90% of the radiolabel ([14C]-p-tert-butylcatechol) was recovered in the urine. For more details see discussion below.
- AF for dose response relationship:
- 3
- Justification:
- For the use of an LOAEL
- AF for differences in duration of exposure:
- 2
- Justification:
- ECHA R8 guidance default factor (subchronic to chronic)
- AF for interspecies differences (allometric scaling):
- 4
- Justification:
- ECHA R8 guidance default factor for rats
- AF for other interspecies differences:
- 2.5
- Justification:
- ECHA R8 guidance default factor
- AF for intraspecies differences:
- 5
- Justification:
- ECHA R8 guidance default factor
Acute/short term exposure
- Hazard assessment conclusion:
- hazard unknown but no further hazard information necessary as no exposure expected
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:
- low hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- low hazard (no threshold derived)
DNEL related information
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
1. Acute / short-term exposure - systemic effects
1.1 For oral route:
The oral route is not relevant to workers.
1.2 For inhalation route:
No valid data are available for this route of administration which is not the most relevant comparing to oral and dermal route.
No DNEL could be calculated. Furthermore there is no potential for high peak exposure in normal conditions of production for this substance.
1.3 For dermal route:
The dermal rat acute toxicity study (CIT, 1992b), where 500 mg/kg was a LOAEL, was taken into consideration. The relevant systemic effects considered are the clinical signs (hypokinesia, sedation and dyspnea) observed within the few hours following cutaneous application. Furthermore local effects characterized by a severe cutaneous reaction were observed at all doses tested.
Due to corrosive effect and regarding the value of the LOAEL, it is possible that local effects always appear before any systemic effects caused by cutaneous absorption. The derivation of an acute worker DNEL by dermal route for systemic effects was therefore considered not relevant. The corrosive effect is considered to appear without threshold. Percutaneous absorption measured in toxicokinetics study confirm that local effect appeared before dermal absorption and seems to facilitate the dermal absorption, without threshold.
Therefore qualitative risk assessment is recommended.
2. Acute / short-term exposure - local effects
For local effects, no sufficient information as to concentration-response relationship of irritation or corrosion is available to enable DNEL derivation.The corrosive effects observed should be considered as the most important hazard and qualitative risk assessment performed for the local effects.
3. Long term exposure - systemic effects
For systemic effects, DNEL derivation was performed following the method proposed in the ECHA Guidance on information requirements and chemical safety assessment, Chapter R.8.
3.1 For oral route:
The oral route is not relevant to workers.
3.2 For inhalation route:
Determination of the human DNEL from rat oral study:
The 14-week rat dietary toxicity study (US NTP, 2002), where the low dose of 781 ppm, equivalent to 70 mg/kg, was a LOAEL, was selected for DNEL derivation. This study was selected preferably to its counterpart in mice, because the rat species appeared more sensitive to the test substance toxicity than the mouse species at the dose levels selected. The relevant systemic effects considered are the changes in hematology and clinical chemistry seen at all dose levels, based on the limited relevance of forestomach lesions also observed in the study but not relevant to humans. These effects were considered to bear a threshold mode of action.
- Modification of the starting point:
According to the same study (US NTP, 2002), in which the excretion of [14C]-p-tert-butylcatechol administered to rats by gavage were analysed, approximately 90% of the radiobabel was recovered in the urine. It is proposed to use precautionary principle and assume that absorption following oral exposure in rats is 90%.
The starting point is therefore converted using an oral-to-inhalation route extrapolation, assuming 90% absorption for oral route and 100% absorption for inhalation, and using standard respiratory volumes of 0.38 m3/kg over 8 hours for rats, 6.7 m3/person over 8 hours and 10 m3/person over 24 hours for humans):
LOAEC worker (8 h)= 70 x (1 / 0.38) x (6.7 / 10) x (90/100) = 111.1 mg/m3
- Assessment factors:
The following assessment factors were applied:
· Remaining interspecies differences (mainly toxicodynamic): 2.5 (default value)
· Intraspecies differences: 5 (default value for workers)
· Differences in duration of exposure: 2 (default value for subchronic to chronic extrapolation)
· Issues related to severity and dose-response: 3 (because of the use of LOAEL as a starting point)
· Quality of whole database: 1 (reliability 1 study).
Global assessment factor = 2.5 x 5 x 2 x 3 x 1= 75
- DNEL:
Worker-DNEL long-term for inhalation route-systemic = 111.1 / 75 = 1.48 mg/m3
3.3 For dermal route:
No repeated-dose dermal toxicity data that would enable DNEL derivation are available.
The corrosive effects observed should be considered as the most important hazard and qualitative risk assessment performed for the local effects.
4. Reproductive and developmental toxicity
Effects on reproductive parameters (sperm count and motility, and estrous cycle parameters) were also noted in the 14-week dietary study in rats (US NTP, 2002). These effects were observed at dose levels higher than those considered for the systemic effect DNEL derivation (LOAEL = 718 ppm).
Therefore the long-term DNEL appears sufficiently protective and no specific DNEL for potential effects on fertility was calculated.
In addition, in order to clarify effects of 4-tert-butylpryrocatechol on the reproduction, an extended one-generation study (OECD TG 443) has been launched (Charles River, 2021). Based on this study no reproduction effects were seen up to the highest tested dose (3125 ppm).
Based on the two OECD 414 test guideline studies (rats and rabbits) and since the substance is not considered as teratogenic for the both species there is no need to derive a DNEL for this endpoint.
General Population - Hazard via inhalation route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- DNEL (Derived No Effect Level)
- Value:
- 365 µg/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):
- 150
- Dose descriptor starting point:
- LOAEL
- Value:
- 70 mg/kg bw/day
- Modified dose descriptor starting point:
- LOAEC
- Value:
- 54.81 mg/m³
- Explanation for the modification of the dose descriptor starting point:
The starting point is converted using an oral-to-inhalation route extrapolation, assuming 90%* absorption for oral route and 100% absorption for inhalation, and using standard respiratory volumes of 1.15 m3/kg over 24 hours for rats:
LOAEC humans via environment (24 h) = 70 x (1 / 1.15) x (90/100)= 54.81 mg/m3
* According to US NTP (2002) study (oral route, rats), approximately 90% of the radiolabel ([14C]-p-tert-butylcatechol) was recovered in the urine. For more details, see discussion below.
- AF for differences in duration of exposure:
- 2
- Justification:
- Subchronic to chronic exposure (ECHA R8 default factor).
- AF for interspecies differences (allometric scaling):
- 1
- Justification:
- Already taken into account in the modification of the starting point.
- AF for other interspecies differences:
- 2.5
- Justification:
- For remaining differences (ECHA R8 default factor).
- AF for intraspecies differences:
- 10
- Justification:
- For general population (ECHA R8 default factor).
Acute/short term exposure
- Hazard assessment conclusion:
- low hazard (no threshold derived)
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
General Population - Hazard via dermal route
Systemic effects
Long term exposure
- Hazard assessment conclusion:
- low hazard (no threshold derived)
Acute/short term exposure
- Hazard assessment conclusion:
- low hazard (no threshold derived)
DNEL related information
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:
- 117 µg/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):
- 600
- Dose descriptor starting point:
- LOAEL
- Value:
- 70 mg/kg bw/day
- Explanation for the modification of the dose descriptor starting point:
No modification of the starting point.
Acute/short term exposure
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
DNEL related information
General Population - Hazard for the eyes
Local effects
- Hazard assessment conclusion:
- medium hazard (no threshold derived)
Additional information - General Population
For systemic effects, DNEL derivation was performed following the method proposed in the ECHA Guidance on information requirements and chemical safety assessment, Chapter R.8.
1. Acute / short-term exposure - systemic effects
1.1 For oral route:
An oral rat acute toxicity study (CIT, 1992a) is available in which clinical signs such as decreased activity, piloerection and dyspnea were observed. These effects were reversible between days 8 and 14. Based on this study, no acute DNEL for systemic effects could be calculated. Indeed, decreased activity and piloerection can be secondary to local GI tract effects and should be considered as part of local effects. In addition, it is likely that dyspnea was a gavage-relating complication.
TBC is corrosive and is classified Skin. Corrosive. Cat. 1B, H314 and Eye. Dam. Cat. 1, H318. In order to protect from local effects, a qualitative risk assessment is recommended. This qualitative risk assessment protects also against systemic effects if any.
1.2 For inhalation route:
No valid data are available for this route of administration which is not the most relevant comparing to oral and dermal route.
No DNEL could be calculated.
1.3 For dermal route:
The dermal rat acute toxicity study (CIT, 1992b), where 500 mg/kg was a LOAEL, was taken into consideration. The relevant systemic effects considered are the clinical signs (hypokinesia, sedation and dyspnea) observed within the few hours following cutaneous application. Furthermore local effects characterized by a severe cutaneous reaction were observed at all doses tested.
Due to corrosive effect and regarding the value of the LOAEL, it is possible that local effects always appear before any systemic effects caused by cutaneous absorption. The derivation of an acute DNEL for humans exposed via environment by dermal route for systemic effects was therefore considered not relevant. The corrosive effect is considered to appear without threshold. Percutaneous absorption measured in toxicokinetics study confirm that local effect appeared before dermal absorption and seems to facilitate the dermal absorption, without threshold.
Therefore qualitative risk assessment is recommended.
2. Acute / short-term exposure - local effects
For local effects, no sufficient information as to concentration-response relationship of irritation or corrosion is available to enable DNEL derivation. The corrosive effects observed should be considered as the most important hazard and qualitative risk assessment performed for the local effects.
3. Long term exposure - systemic effects
For systemic effects, DNEL derivation was performed following the method proposed in the ECHA Guidance on information requirements and chemical safety assessment, Chapter R.8.
3.1 For oral route:
The 14-week rat dietary toxicity study (US NTP, 2002), where the low dose of 781 ppm, equivalent to 70 mg/kg, was a LOAEL, was selected for DNEL derivation. This study was selected preferably to its counterpart in mice, because the rat species appeared more sensitive to the test substance toxicity than the mouse species at the dose levels selected. The relevant systemic effects considered are the changes in hematology and clinical chemistry seen at all dose levels, based on the limited relevance of forestomach lesions also observed in the study but not relevant to humans. These effects were considered to bear a threshold mode of action.
- Modification of the starting point:
No modification of the starting point is applied as the routes of exposure are the same in both species.
- Assessment factors:
The following assessment factors were applied:
· Interspecies differences (mainly toxicokinetic): 4 (default value)
· Remaining interspecies differences (mainly toxicodynamic): 2.5 (default value)
· Intraspecies differences: 10 (default value for humans exposed via environment)
· Differences in duration of exposure: 2 (default value for subchronic to chronic extrapolation)
· Issues related to severity and dose-response: 3 (because of the use of LOAEL as a starting point)
· Quality of whole database: 1 (reliability 1 study).
Global assessment factor = 4 x 2.5 x 10x 2 x 3 = 600
- DNEL:
Human via environment-DNEL long-term for oral route-systemic = 70 / 600 = 117 µg/kg bw/day
3.2 For inhalation route:
Determination of the human DNEL from rat oral study:
The same 14-week rat dietary toxicity study (US NTP, 2002), where the low dose of 781 ppm, equivalent to 70 mg/kg, was a LOAEL, was selected for DNEL derivation, using route-to-route extrapolation.
- Modification of the starting point:
According to the same study (US NTP, 2002), in which the excretion of [14C]-p-tert-butylcatechol administered to rats by gavage were analysed, approximately 90% of the radiolabel was recovered in the urine. It is proposed to use precautionary principle and assume that adsorption following oral exposure in rat is 90%.
The starting point is converted using an oral-to-inhalation route extrapolation, assuming 90% absorption for oral route and 100% absorption for inhalation, and using standard respiratory volumes of 1.15 m3/kg over 24 hours for rats:
LOAEC humans via environment (24 h) = 70 x (1 / 1.15) x (90/100) = 54.81 mg/m3
- Assessment factors:
The following assessment factors were applied:
· Remaining interspecies differences (mainly toxicodynamic): 2.5 (default value)
· Intraspecies differences: 10 (default value for humans exposed via environment)
· Differences in duration of exposure: 2 (default value for subchronic to chronic extrapolation)
· Issues related to severity and dose-response: 3 (because of the use of LOAEL as a starting point)
· Quality of whole database: 1 (reliability 1 study).
Global assessment factor = 2.5 x 10x 2 x 3 = 150
- DNEL:
Human via environment-DNEL long-term for inhalation route-systemic = 54.81 / 150 = 365 µg/m3
3.3 For dermal route:
No repeated-dose dermal toxicity data that would enable DNEL derivation are available.
The corrosive effects observed should be considered as the most important hazard and qualitative risk assessment performed for the local effects.
4. Reproductive and developmental toxicity
Effects on reproductive parameters (sperm count and motility, and estrous cycle parameters) were also noted in the 14-week dietary study in rats (US NTP, 2002). These effects were observed at dose levels higher than those considered for the systemic effect DNEL derivation (LOAEL = 718 ppm).
Therefore the long-term DNEL appears sufficiently protective and no specific DNEL for potential effects on fertility was calculated.
In addition, in order to clarify effects of 4-tert-butylpryrocatechol on the reproduction, an extended one-generation study (OECD TG 443) has been launched (Charles River, 2021). Based on this study no reproduction effects were seen up to the highest tested dose (3125 ppm).
Based on the two OECD 414 test guideline studies (rats and rabbits) and since the substance is not considered as teratogenic for the both species there is no need to derive a DNEL for this endpoint.
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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