1,4-Dihydroxy-2,2,6,6-tetramethylpiperidine

Endpoint summary

Description of key information

The acute oral median lethal dose (LD50) of the test item in the male and female Sprague Dawley strain rat was  200 - 2000 mg/kg bodyweight, based on this the acute point toxicity estimate is 500 mg/kg bw.

In an acute dermal toxicity test the limit dose of 2000 mg/kg bw did not lead to mortality, the dermal LD50 is therefore >2000.

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Male and female Sprague Dawley CD strain rats were supplied by Charles River UK Ltd.
- Age at study initiation: Eight to twelve weeks of age
- Weight at study initiation: males 230 - 265g and females 209 - 241g. The bodyweights fell within an interval of ±20% of the mean initial bodyweight of the first treated group.
- Fasting period before study: Overnight fast immediately before dosing and for approximately three to four hours after dosing
- Housing: The animals were housed in groups of three by sex in suspended solid floor polypropylene cages furnished with woodflakes.
- Diet (e.g. ad libitum): Food (Rat and mouse expandd diet No. 1, Special Diets Services LTD) was allowed throughout the study.
- Water (e.g. ad libitum): Free access to mains drinking water was allowed throughout the study.
- Acclimation period: At least five days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Set to achieve limits of 19 to 25°C
- Humidity (%): Set to achieve limits of 30 to 70%
- Air changes (per hr): At least fifteen changes per hour
- Photoperiod (hrs dark / hrs light): lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 200mg/ml for 2000 mg/kg dose level, 20mg/ml for 200 mg/kg dose level

DOSE VOLUME APPLIED:
10ml/kg

DOSAGE PREPARATION:
For the purpose of the study the test material was freshly prepared, as required as a suspension at the appropriate concentration in dried arachis. Preparation was aided by the use of a vortex mixer and homogeneity was assured by the use of a Silverson homogeniser.

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 bodyweight at the time of dosing. Treatment of animals was sequential. Sufficient time was allowed between each dose level to confirm the survival of the previously dosed animals.

Doses:

200 mg/kg and 2000 mg/kg

No. of animals per sex per dose:

3 females and 3 males at 2000 mg/kg
3 females and 3 males at 200 mg/kg

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days

- Frequency of observations and weighing: The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for up to fourteen days.

Individual bodyweights were recorded prior to dosing and seven and fourteen days after treatment or at death.

- Necropsy of survivors performed: yes; At the end of the observation period the surviving animals were killed by cervical dislocation. All animals were subjected to gross pathological examination. This consisted of an external examination and opening of the abdominal and thoracic cavities for examination of major organs. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 200 - <= 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: Mortalities were observed at 2000mg/kg bw, no mortalities were observed at 200 mg/kg bw

Mortality:

Individual mortality data are given the attached background material.
Three animals treated with 2000 mg/kg (one female and two males) were found dead either on the day of dosing or one day after the day of dosing. There were no deaths observed at the dose level of 200 mg/kg.

Clinical signs:

other: Individual clinical observations are given in the attached background information. Signs of toxicity observed at a dose level of 2000 mg/kg were ataxia, hunched posture and lethargy with additional signs of elevated tail, ptosis decreased respiratory rate

Gross pathology:

Individual necropsy findings are given in the attached background information.
Abnormalities observed at necropsy of animals that died during the study were haemorrhagic lungs, dark liver, dark kidneys, haemorrhagic gastric mucosa and haemorhagic small and large intestine.
No abnormalities were noted at necropsy of animals that were killed at the end of the study.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

The acute oral median lethal dose (LD50) of the test item in the male and female Sprague Dawley strain rat was estimated to be 200 - 2000 mg/kg bodyweight (Globally Harmonised Classification System – Category 4).

Executive summary:

Introduction.

The study was performed to assess the acute oral toxicity of the test item following a single oral administration in the Sprague Dawley strain rat. The method was designed to be compatible with the following

- OECD Guidelines for the Testing of Chemicals No. 423 “Acute Oral Toxicity – Acute Toxic Class Method” (adopted 22 March 1996)

- Method B1trisAcute Toxicity (Oral) of Commission Directive 96/54/EC

Method.

A group of three fasted females was treated with the test item at a starting dose of 2000 mg/kg bodyweight. This was followed by a group of three fasted males at the same dose level. Based on the results from this dose level further groups of fasted animals were treated at a dose level of 200 mg/kg bodyweight. Dosing was performed sequentially.

The test item was administered orally as a suspension in dried arachis oil BP. The animals were observed ½, 1, 2 and 4 hours after dosing and once daily for upto fourteen days. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality. 

One female and two males treated with 2000 mg/kg died during the study.

Clinical Observations. 

The following signs of systemic toxicity were observed at a dose level of 2000 mg/kg,ataxia, hunched posture and lethargy with additional signs of elevated tail, ptosis decreased respiratory rate, laboured respiration, occasional body tremors and splayed gait.

Bodyweight. 

All surviving animals showed expected gains in bodyweight over the study period.

Necropsy. 

Abnormalities observed at necropsy of animals that died during the study were haemorrhagic lungs, dark liver, dark kidneys, haemorrhagic gastric mucosa and haemorhagic small and large intestine.

No abnormalities were noted at necropsy of animals that were killed at the end of the study.

Conclusion.

The acute oral median lethal dose (LD50) of the test item in the male and female Sprague Dawley strain rat was estimated to be 200 - 2000 mg/kg bodyweight (Globally Harmonised Classification System – Category 4).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

500 mg/kg bw

Quality of whole database:

The study has been conducted according to OECD Guideline 423 and GLP and is adequately reported. The study has been assigned a reliability 1.

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Five male and five femake Sprague Dawley CD (Crl : CD (SD) IGS BR) strain rats were supplied by Charles River UK Ltd., Margate, Kent.
- Age at study initiation: Eight to twelve weeks of age
- Weight at study initiation: 207 - 242g males and 209 - 230g females.
- Fasting period before study: None.
- Housing: The animals were housed in suspended solid-floor polypropylene cages furnished with woodflakes. The animals were housed individually during the 24-Hour exposure period and in groups of five, by sex, for the remainder of the study.
- Diet (e.g. ad libitum): Free access to food (Rat and Mouse Expanded Diet No.1, Special Diets Services Limited, Witham Essex, UK) was allowed throughout the study.
- Water (e.g. ad libitum): Free access to mains drinking water was allowed throughout the study.
- Acclimation period: At least five days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Set to achieve limits of 19 to 25°C
- Humidity (%): Set to achieve limits of 30 to 70%
- Air changes (per hr): At least fifteen changes per hour
- Photoperiod (hrs dark / hrs light): lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.

Type of coverage:

semiocclusive

Vehicle:

other: The test material was moistened with dried arachis oil

Details on dermal exposure:

PROCEDURE:
On the day before treatment the back and flanks of each animal were clipped free of hair.

A group of 5 males and 5 females was treated with the test material at a dose level of 2000 mg/kg.

The appropriate amount of test material moistened with dried arachis oil BP was applied uniformly to an area of shorn skin (approximately 10% of the total body surface area). A piece of surgical gauze was placed over the treatment area and semi-occluded with a piece of self-adhesive bandage. The animals were caged individually for the 24-Hour exposure period. Shortly after dosing the dressings were examined to ensure that they were securely in place.

REMOVAL OF TEST SUBSTANCE:
After the 24-Hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with dried arachis oil BP to remove any residual test item. The animals were returned to group housing for the remainder of the study period.

Duration of exposure:

24 hours

Doses:

2000 mg/kg body weight

No. of animals per sex per dose:

5 male and 5 female at 2000 mg/kg

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days

- Frequency of observations and weighing:
The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for fourteen days.

After removal of the dressings and subsequently once daily for fourteen days, the test sites were examined for evidence of primary irritation and scored according to the Draize scale (see evaluation of skin reactions).

Any other skin reactions, if present were also recorded.

Individual bodyweights were recorded prior to application of the test item on Day 0 and on Days 7 and 14.

- Necropsy of survivors performed: yes
At the end of the study the animals were killed by cervical dislocation. All animals were subjected to gross necropsy. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

Individual mortality data are given in the attached background material.
There were no deaths.

Clinical signs:

other: Individual clinical observations are given in the attached background material. No clinical signe of toxicity were noted during the study.

Gross pathology:

Individual necropsy findings are given in the attached background material.
No abnormalities were noted at necropsy.

Other findings:

Dermal Reactions:
Individual dermal reactions are given in the attached background material.
No signs of dermal irritation were noted during the study.

Interpretation of results:

GHS criteria not met

Conclusions:

The acute dermal median lethal dose (LD50) of the test item in the Sprague Dawley strain rat was found to be >2000 mg/kg bodyweight.

Executive summary:

Introduction.

The study was performed to assess the acute dermal toxicity of the test item in the Sprague Dawley strain rat. The method was designed to be compatible with the following:

• OECD Guidelines for the Testing of Chemicals No. 402 "Acute Dermal Toxicity" (adopted 24 February 1987)

• Method B3 Acute Toxicity (Dermal) of Commission Directive 92/69/EEC

Method.

A group of ten animals (five males and five females) was given a single, 24 hour, semi-occluded dermal application of the undiluted test item to intact skin at a dose level of 2000 mg/kg bodyweight. The animals were observed for 14 days, clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality.

There were no deaths at 2000 mg/kg.

Clinical Observations.

There were no signs of systemic toxicity or dermal irritation

Bodyweight.

All animals showed expected gains in bodyweight over the study period.

Necropsy.

No abnormalities were noted at necropsy.

Conclusion.

The acute dermal median lethal dose (LD50) of the test item in the Sprague Dawley CD strain rat was found to be >2000 mg/kg bodyweight and therefore did not meet the criteria for classification according to the Classification, Labelling and Packaging Regulation (CLP) .

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The study has been conducted according to OECD Guideline 402 and GLP and is adequately reported. The study has been assigned a reliability 1.

Additional information

Acute Oral Toxicity

The study was performed to assess the acute oral toxicity of the test item following a single oral administration in the Sprague Dawley strain rat. The method was designed to be compatible with the following

- OECD Guidelines for the Testing of Chemicals No. 423 “Acute Oral Toxicity – Acute Toxic Class Method” (adopted 22 March 1996)

- Method B1trisAcute Toxicity (Oral) of Commission Directive 96/54/EC

A group of three fasted females was treated with the test item at a starting dose of 2000 mg/kg bodyweight. This was followed by a group of three fasted males at the same dose level. Based on the results from this dose level further groups of fasted animals were treated at a dose level of 200 mg/kg bodyweight. Dosing was performed sequentially.

The test item was administered orally as a suspension in dried arachis oil BP. The animals were observed ½, 1, 2 and 4 hours after dosing and once daily for upto fourteen days. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality: One female and two males treated with 2000 mg/kg died during the study.

Clinical Observations: The following signs of systemic toxicity were observed at a dose level of 2000 mg/kg,ataxia, hunched posture and lethargy with additional signs of elevated tail, ptosis decreased respiratory rate, laboured respiration, occasional body tremors and splayed gait.

Bodyweight: All surviving animals showed expected gains in bodyweight over the study period.

Necropsy: Abnormalities observed at necropsy of animals that died during the study were haemorrhagic lungs, dark liver, dark kidneys, haemorrhagic gastric mucosa and haemorhagic small and large intestine.

No abnormalities were noted at necropsy of animals that were killed at the end of the study.

Conclusion:

The acute oral median lethal dose (LD50) of the test item in the male and female Sprague Dawley strain rat was estimated to be 200 - 2000 mg/kg bodyweight (Globally Harmonised Classification System – Category 4).

Acute Dermal Toxicity

The study was performed to assess the acute dermal toxicity of the test item in the Sprague Dawley strain rat. The method was designed to be compatible with the following:

• OECD Guidelines for the Testing of Chemicals No. 402 "Acute Dermal Toxicity" (adopted 24 February 1987)

• Method B3 Acute Toxicity (Dermal) of Commission Directive 92/69/EEC

A group of ten animals (five males and five females) was given a single, 24 hour, semi-occluded dermal application of the undiluted test item to intact skin at a dose level of 2000 mg/kg bodyweight. The animals were observed for 14 days, clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality: There were no deaths at 2000 mg/kg.

Clinical Observations: There were no signs of systemic toxicity or dermal irritation

Bodyweight: All animals showed expected gains in bodyweight over the study period.

Necropsy: No abnormalities were noted at necropsy.

Conclusion:

The acute dermal median lethal dose (LD50) of the test item in the Sprague Dawley CD strain rat was found to be >2000 mg/kg bodyweight and therefore did not meet the criteria for classification according to the Classification, Labelling and Packaging Regulation (CLP) .

Justification for classification or non-classification

The substance is classified as Acute Toxicity Category 4 - H302: Harmful if swallowed, in accordance with Regulation (EC) No 1272/2008.