2,4,6-tri-tert-butylphenol

Endpoint summary

Description of key information

ORAL
A single acute toxicity study is currently available in which the acute oral LD50 of the substance was determined to be >200 mg/kg in the rat.
DERMAL
A single acute toxicity study is currently available in which the acute dermal LD50 of the substance was determined to exceed 2000 mg/kg in the rat.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

200 mg/kg bw

Quality of whole database:

A single study of reliability K2 is available to address this endpoint. The quality of the database is therefore considered to be good.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

A single study of reliability K1 is available to address this endpoint. The quality of the database is therefore considered to be high.

Additional information

Oral

A single acute toxicity study is currently available as a part of the data set on this substance. It has been assigned a reliability score of 2 according to the criteria of Klimisch et al. (1997) and has therefore been used for chemical safety assessment. In this study the acute toxicity potential of the test material was investigated in a study conducted in accordance with the standardised guidelines OECD 401 and EU Method B.1 under GLP conditions. A group of ten fasted Sprague-Dawley rats (five males and five females) was given a single oral dose of the test material as a suspension in arachis oil B.P. at a dose level of 2000 mg/kg bodyweight. An additional group of ten fasted animals was then treated with the test material administered as a suspension in arachis oil B.P. a t a dose level of 200 mg/kg bodyweight. The surviving animals were observed for fourteen days. All animals were subjected to a gross pathological examination. Two females treated with 2000 mg/kg were found dead one day after dosing. Four animals (one male and three females) in this group were killed in extremis one or four days after dosing. Common signs of systemic toxicity noted in this group were ataxia, hunched posture, lethargy, decreased respiratory rate and laboured respiration with additional signs of ptosis and loss of righting reflex. Surviving animals in this group recovered three or ten days after dosing. There were no deaths or signs of systemic toxicity noted in animals treated with 200 mg/kg. One male treated with 2000 mg/kg showed a slightly reduced gain in bodyweight during week one. All other surviving animals showed the expected gain in bodyweight during the study. Abnormalities noted at necropsy of animals that died or were killed in extremis during the study were haemorrhagic lungs, dark or pale liver, patchy pallor of the liver or red-coloured possible necrosis of the liver and haemorrhagic or pale gastric mucosa. No abnormalities were noted at necropsy of one female treated with 2000 mg/kg that was killed in extremis during the study, four males treated with 2000 mg/kg and animals treated with 200 mg/kg that were sacrificed at the end of the study. Under the conditions of this study the LD50 was found to be greater than 200 mg/kg bw but less than 2000 mg/kg bw.

 

Dermal

A single acute toxicity study is currently available as a part of the data set on this substance. It has been assigned a reliability score of 1 according to the criteria of Klimisch et al. (1997) and has therefore been used for chemical safety assessment.

The potential of the test material to cause acute dermal toxicity in the rat was investigated in accordance with the standardised guidelines OECD 402, EU Method B.3, US EPA OPPTS 870.1200 and JMAFF 12 Nousan, Notification No 8147 under GLP conditions.

The test material was administered to five Wistar rats of each sex by a single dermal application in an occlusive fashion at a limit dose of 2000 mg/kg body weight for 24 hours. After the exposure period, dressings were removed and the skin cleaned of residual test material using tap water. Animals were subjected to daily observations and weekly determination of body weight. Macroscopic examination was performed after terminal sacrifice (Day 15). No mortality occurred and there were no clinical signs noted for the animals. However, general erythema was noted for one female animal on Day 2. The changes noted in body weight gain in males and females were within the range expected for rats used in this type of study and were therefore considered not indicative of toxicity.

No abnormalities were found at macroscopic post mortem examination of the animals.

Under the conditions of this study the LD50 value was found to exceed 2000 mg/kg bw.

Justification for selection of acute toxicity – oral endpoint
A single study assessing this endpoint was available. As such the results of this study have been used for chemical safety assessment.

Justification for selection of acute toxicity – dermal endpoint
A single study assessing this endpoint was available. As such the results of this study have been used for chemical safety assessment.

Justification for classification or non-classification

Oral

Under the conditions of the available study (Tuffnell, 1992), the LD50 of the substance was determined to be between 200 and 2000 mg/kg. In the absence of information to the contrary and as a worst case scenario, the substance has been determined to require classification in accordance with the criteria for classification as defined in Annex I, Regulation (EC) No. 1272/2008 as Acute toxicity: Category 3 via the oral route and will be assigned the Hazard Statement H301: Toxic if swallowed.

 

Dermal 

In accordance with the criteria for classification as defined in Annex I, Regulation (EC) No 1272/2008, the substance does not require classification with respect to acute dermal toxicity.