2,5-di-tert-butylhydroquinone

Endpoint summary

Description of key information

Oral (OECD 420); di-tert-butyl hydroquinone; LD50 50 mg/kg bw

Dermal (OECD 402); di-tert-butyl hydroquinone; LD50 > 2 000 mg/kg bw

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 (Acute Toxicity (Oral))

Deviations:

no

GLP compliance:

yes

Test type:

fixed dose procedure

Limit test:

no

Specific details on test material used for the study:

The test substance is identified as di-tert-butyl hydroquinone. The purity is 99.6%. The physical state/appearance of material is white solid. The expiry date of material is 01 march 2019. The substance can be stored at room temperature in the dark conditions.

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

Female Wistar (RccHanTM :WIST) strain rats were supplied by Envigo RMS (UK) Limited, Oxon, UK. On receipt the animals were randomly allocated to cages. The females were nulliparous and non-pregnant. After an acclimatization period of at least 5 days the animals were selected at random and given a number unique within the study by indelible ink-marking on the tail and a number written on a cage card. At the start of the study the animals were 8 to 12 weeks of age. The body weight variation did not exceed ±20% of the mean body weight at the start of treatment.

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

All animals were dosed once only by gavage, using a metal cannula attached to a graduated syringe. The volume administered to each animal was calculated according to the fasted body weight at the time of dosing. Treatment of animals was sequential. Sufficient time was allowed between each dose group to confirm the survival of the previously dosed animals.

Doses:

300 and 50

Details on study design:

A total of five animals were therefore treated at a dose level of 50 mg/kg in the study and 1 for 300 mg/kg.

Sex:

female

Dose descriptor:

LD50

Effect level:

50 - 300 mg/kg bw

Based on:

test mat.

Mortality:

The animal treated at a dose level of 300 mg/kg was killed for humane reasons, 1 day after dosing, due to the occurrence of clinical signs of toxicity that approached the severity limit set forth in the UK Home Office Project Licence. There were no deaths noted at a dose level of 50 mg/kg

Clinical signs:

other: Signs of systemic toxicity noted in the animal treated at a dose level of 300 mg/kg were ataxia, hunched posture, lethargy, pilo-erection, ptosis, occasional body tremors, tiptoe gait, emaciation, pallor of the extremities, hypothermia and elevated tail.

Gross pathology:

Hemorrhagic non-glandular epithelium of the stomach was noted at necropsy of the animal treated at a dose level of 300 mg/kg. No abnormalities were noted at necropsy of animals treated at a dose level of 50 mg/kg.

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

The acute oral median lethal dose (LD50) of the test item in the female Wistar strain rat was estimated to be in the range of 50 - 300 mg/kg body weight (Globally Harmonized Classification System — Category 3).

Executive summary:

The study was performed to assess the acute oral toxicity of the test item in the Wistar strain rat. Following a sighting test at dose levels of 300 mg/kg and 50 mg/kg, a further group of four fasted females was given a single oral dose of test item, as a suspension in arachis oil BP, at a dose level of 50 mg/kg body weight. Clinical signs and body weight development were monitored during the study. All animals were subjected to gross necropsy. The animal treated at a dose level of 300 mg/kg was killed for humane reasons, 1 day after dosing, due to the occurrence of clinical signs of toxicity that approached the severity limit set forth in the UK Home Office Project Licence. There were no deaths noted at a dose level of 50 mg/kg. Signs of systemic toxicity noted in the animal treated at a dose level of 300 mg/kg were ataxia, hunched posture, lethargy, pilo-erection, ptosis, occasional body tremors, tiptoe gait, emaciation, pallor of the extremities, hypothermia and elevated tail. There were no signs of systemic toxicity noted at a dose level of 50 mg/kg.

Animals treated at a dose level of 50 mg/kg showed expected gains in body weight. In necropsy Hemorrhagic non-glandular epithelium of the stomach was noted at necropsy of the animal treated at a dose level of 300 mg/kg. No abnormalities were noted at necropsy of animals treated at a dose level of 50 mg/kg.The acute oral median lethal dose (LD50) of the test item in the female Wistar strain rat was estimated to be in the range of 50 - 300 mg/kg body weight (Globally Harmonized Classification System — Category 3).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

50 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 August 2019 - 23 September 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

GLP compliance:

yes

Test type:

fixed dose procedure

Limit test:

yes

Specific details on test material used for the study:

Name of Test Item : YAPOX 2245
Chemical Name (IUPAC) : 2,5-Di-tertiary butyl hydroquinone
CAS No. : 88-58-4
Physical Appearance (with color) : White to light tan Crystalline powder
Batch No. : 20015011219
Purity (as per Certificate of Analysis) : 99.37%
Date of Manufacture : June 2019
Date of Expiry : May 2021
Storage Condition : Ambient (21 to 29ºC)
Batch Produced by
(Name and address) : YASHO INDUSTRIES LIMITED
Plot No. 2514/2515, Phase IV, G. I. D. C.,
Vapi- 396195, Gujarat, India
Test Item Code by Test Facility : D819-002

Species:

rat

Strain:

Sprague-Dawley

Sex:

female

Details on test animals or test system and environmental conditions:

Source of Supply : In-house bred animals
Body Weight Range at Receipt : Between 203 and 220 g
No. of Animals and Sex : Total of 05 females were received (Females used were nulliparous and non-pregnant)
Age at Treatment : 10 to 11 weeks
Animal Identification : Acclimatization period: All the animals were identified by tail marking using a black permanent marker pen and cage cards.
Treatment period:The animals were identified by writing last four digits of animal number on tail using a red permanent marker pen and cage cards.
Environmental Conditions : Animals were housed under standard laboratory conditions, in an environmentally monitored air-conditioned room with adequate fresh air supply (12 to 15 air changes per hour), room temperature 22±3°C and relative humidity 30% to 70% with 12 hours fluorescent light and 12 hours dark cycle. The temperature and relative humidity were recorded once daily.
Housing : Maximum three animals were housed in a standard polypropylene cage (size: L 430 x B 285 x H 150 mm) with stainless steel mesh top grill having facilities for holding pelleted feed and drinking water in water bottle fitted with stainless steel sipper tube. For range finding study animals were housed individually after treatment. For main study, during treatment, the animals were housed individually; and after patch removal, animals were housed together. Clean sterilized paddy husk were provided as bedding material. Paper shredding will be provided as enrichment.
Feed : Altromin maintenance diet for rats and mice (manufactured by Altromin Spezialfutter GmbH & Co. KG) were provided ad libitum to the animals throughout the experimental period. T
Water : Water was provided ad libitum throughout the acclimatization and experimental period. Deep bore-well water passed through Reverse osmosis unit was provided in plastic water bottles with stainless steel sipper tubes.
Acclimatization : Healthy and young adult animals were acclimatized for a minimum period of five days to laboratory conditions prior to dosing and were observed for clinical signs once daily. Veterinary examination of all the animals was performed on the day of receipt and on 5th day of acclimatization.

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: not specified
- % coverage: 10
- Type of wrap if used: The area was covered with cotton gauze and held in place with non-irritating adhesive tape. The whole area was wrapped with a suitable semi-occlusive dressing (crepe bandage).

REMOVAL OF TEST SUBSTANCE
- Washing (if done): At the end of the contact period, the residual test item was washed using distilled water and dried with absorbent cotton.
- Time after start of exposure: 24h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): The dose volume eas calculated based on the body weight
- Concentration (if solution): undiluted
- Constant volume or concentration used: no

Duration of exposure:

24h

Doses:

The dose levels of 200, 1000 and 2000 mg/kg body weight.

No. of animals per sex per dose:

Range finding Study:
200 mg/kg : 1F
1000 mg/kg : 1F
2000 mg/kg : 1F
Main study
2000 mg/kg : 2F

Control animals:

not required

Details on study design:

The study was performed in two phases that is range finding study and main study. Range finding study was performed with one animal and main study was performed with two animals.
The animals were dosed in a stepwise procedure with one female in range finding study. As the LD50 of the test item was not available a starting dose of 200 mg/kg body weight was selected from the fixed dose levels of 50, 200, 1000 and 2000 mg/kg body weight. Depending on the presence or absence of moribund conditions or mortality, further animals were treated as per the OECD 402 guideline Annex 2.
Dosing was sequential, allowing at least 48 hours between the testing of each step. The time interval between dosing at each level was determined by the onset, duration and severity of toxic signs.
Based on the outcome of range finding study, further dose was selected for the main study and treatment was carried out with two animals. Details of the step wise test procedure according to the OECD 402 guideline is presented as Annexure 1.
The test item was applied topically (dermal exposure). Required volume of the test item was calculated based on individual animal body weight and then undiluted test item was applied on the clipped area (approximately 10% of the total body surface area) and was covered with cotton gauze and held in place with non-irritating adhesive tape. The whole area was wrapped with a suitable semi-occlusive dressing (crepe bandage). The contact period of test item was 24 hours. At the end of the contact period, the residual test item was washed using distilled water and dried with absorbent cotton.
For example:
Volume applied (mL) = Dose (mg/kg)/1000 x Body weighyt (g) / Density (mg/mL)
All the animals were observed for clinical signs of toxicity and mortality at 20 to 30 min, 1 hr (±10 mins), 2 hrs (±10 mins), 4 hrs (±10 mins) and 6 hrs (±10 mins) post dosing on day 1 and thereafter at least once daily for clinical signs of toxicity and twice daily for mortality during the 14 days observation period. Individual animal body weight was recorded at receipt, on day 1 before test item application and on day 8 and 15 during the experimental period.
At the end of observation period on day 15, all surviving animals were humanely sacrificed by carbon dioxide asphyxiation and subjected to gross pathological examination.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

no indication of skin irritation up to the relevant limit dose level

Mortality:

no mortalility was observed

Clinical signs:

other: no clinical signs were observed

Gross pathology:

No gross pathological chenges were observed

Interpretation of results:

GHS criteria not met

Conclusions:

The acute dermal median lethal dose (LD50) of test item YAPOX 2245 in Sprague Dawley rats is >2000 mg/kg body weight

Executive summary:

YAPOX 2245 was evaluated for acute dermal toxicity in Sprague Dawley rats as per the OECD Guideline 402. The study was performed in two phases i.e range finding study and main study. The study animals were dosed in a stepwise procedure with one female in range finding study. Range finding study was performed with three female rats (one rat per each dose) and main study was performed with two female rats. On the day before the application of the test item, fur on the dorso-lateral area of the trunk of the animals was removed by clipping closely with an electric hair clipper and care was taken to avoid abrading the skin. Required volume of the test item was calculated based on individual animal body weight and then undiluted test item was applied on the clipped area and was covered with cotton gauze and held in place with non-irritating adhesive tape. the whole are was wrapped with a sutable semi-occlusive dressing. The contact period of the test item was 24 hours. At the end of the contact period, the residual test item was washed using distilled water and dried with absorbent cotton.

No clinical signs and mortalities were observed at the dose level of 200 mg/kg bw. Further one animal was dosed at 1000 mg/kg bw. No clinical signs and mortalities were observed at the dose level of 1000 mg/kg bw in range finding study. Next one animal was dosed at 2000 mg/kg bw. No clinical signs and mortalities were observed at the dose level of 2000 mg/kg bw in range finding study. hence, during main study two animals were administered with the same dose level of 2000 mg/kg bw. No clinical signs and mortalities were observed at the dose level of 2000 mg/kg bw in the main study.

All animals were observed for clinical signs of toxicity and mortality at 20 to 30 min, 1 hrs, 2hrs, 4 hrs, and 6 hrs on treatment day 1 and thereafter once daily for clinical signs of toxicity and twic daily for mortality during the 14 days observation period. The body weight was recorded on day 1 before test item application and on day 8 and 15. At the end of observation period, all the animals were humanely sacrificed and subjected to necropsy and detailed gross pathological examination.

No mortality, clinical signs and skin reactions were noted. No treatment related changes in body weights and percent change in body weight with respect to day 1 were noted. Normal increase in body weights were noted during the observation period. No treatment related gross pathological changes were noted in any of the dosed animals during necropsy.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

ACUTE ORAL TOXICITY

A key acute oral toxicity study was conducted according to Guideline OECD 420. Signs of systemic toxicity noted in the animal treated at a dose level of 300 mg/kg were ataxia, hunched posture, lethargy, pilo-erection, ptosis, occasional body tremors, tiptoe gait, emaciation, pallor of the extremities, hypothermia and elevated tail. There were no signs of systemic toxicity noted at a dose level of 50 mg/kg. Animals treated at a dose level of 50 mg/kg showed expected gains in body weight. Hemorrhagic non-glandular epithelium of the stomach was noted at necropsy of the animal treated at a dose level of 300 mg/kg. No abnormalities were noted at necropsy of animals treated at a dose level of 50 mg/kg. The acute oral median lethal dose (LD50) of the test item in the female Wistar strain rat was estimated to be in the range of 50 - 300 mg/kg body weight.

ACUTE DERMAL TOXICITY

2,5,-di-tert-butylhydroquinone was evaluated for acute dermal toxicity in Sprague Dawley rats as per the OECD Guideline 402. The study was performed in two phases i.e range finding study and main study. The study animals were dosed in a stepwise procedure with one female in range finding study. Range finding study was performed with three female rats (one rat per each dose) and main study was performed with two female rats. On the day before the application of the test item, fur on the dorso-lateral area of the trunk of the animals was removed by clipping closely with an electric hair clipper and care was taken to avoid abrading the skin. Required volume of the test item was calculated based on individual animal body weight and then undiluted test item was applied on the clipped area and was covered with cotton gauze and held in place with non-irritating adhesive tape. the whole are was wrapped with a sutable semi-occlusive dressing. The contact period of the test item was 24 hours. At the end of the contact period, the residual test item was washed using distilled water and dried with absorbent cotton.

No clinical signs and mortalities were observed at the dose level of 200 mg/kg bw. Further one animal was dosed at 1000 mg/kg bw. No clinical signs and mortalities were observed at the dose level of 1000 mg/kg bw in range finding study. Next one animal was dosed at 2000 mg/kg bw. No clinical signs and mortalities were observed at the dose level of 2000 mg/kg bw in range finding study. hence, during main study two animals were administered with the same dose level of 2000 mg/kg bw. No clinical signs and mortalities were observed at the dose level of 2000 mg/kg bw in the main study.

All animals were observed for clinical signs of toxicity and mortality at 20 to 30 min, 1 hrs, 2hrs, 4 hrs, and 6 hrs on treatment day 1 and thereafter once daily for clinical signs of toxicity and twic daily for mortality during the 14 days observation period. The body weight was recorded on day 1 before test item application and on day 8 and 15. At the end of observation period, all the animals were humanely sacrificed and subjected to necropsy and detailed gross pathological examination.

No mortality, clinical signs and skin reactions were noted. No treatment related changes in body weights and percent change in body weight with respect to day 1 were noted. Normal increase in body weights were noted during the observation period. No treatment related gross pathological changes were noted in any of the dosed animals during necropsy.

Justification for classification or non-classification

Di-tert-butyl hydroquinone is classified for Acute Oral Tox. Cat. 3 H301 according to the CLP Regulation No. 1272/2008.No classification is warranted via dermal route.