6,6'-di-tert-butyl-2,2'-methylenedi-p-cresol

Endpoint summary

Description of key information

The acute dermal and oral toxicity of the test substance 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (DBMC) is very low, indicated by LD50 values greater than 5000 mg/kg. The acute oral LD50 value in rats is greater than 5000 mg/kg bw mg/kg (Takagi 1994) and the dermal LD50 value in rabbits is greater than 10000 mg/kg bw (American Cyanamid Company 1965). 

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: limited but acceptable documented study report which meets basic scientific principles

Principles of method if other than guideline:

other: acute oral toxicity study

GLP compliance:

no

Test type:

other: acute oral toxicity study

Species:

rat

Strain:

other: Albino rats

Sex:

male

Route of administration:

oral: gavage

Vehicle:

water

Doses:

10000 mg/kg

No. of animals per sex per dose:

10 males

Control animals:

no

Sex:

male

Dose descriptor:

LD50

Effect level:

> 10 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: clinical signs: depression

Clinical signs:

other:

Mortality: no death occurred during the study

Clinical signs: depression, noted 6 to 24 h after test substance application, recovery 24 h after application

Gross autopsy: normal

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: limited but acceptable documented study report which meets basic scientific principles

Principles of method if other than guideline:

other: acute dermal toxicity study

GLP compliance:

no

Test type:

other: acute dermal toxicity study

Species:

rabbit

Strain:

other: Albino rabbit (no additional data given)

Sex:

male

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Duration of exposure:

24 h

Doses:

10000 mg/kg bw

No. of animals per sex per dose:

5 males per dose

Control animals:

not required

Sex:

male

Dose descriptor:

LD50

Effect level:

> 10 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: no mortality and clinical signs observed during the study

Clinical signs:

other:

Mortality: none during the study (0/5)

Skin irritation: not observed during the study

Clinical signs: not observed during the study

Gross autopsy: normal

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

10 000 mg/kg bw

Additional information

Acute toxicity: oral

The oral toxicity of 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (DBMC) was evaluated in several studies with rats or mice. The available study data are limited compared to current guideline studies, but are acceptable well-documented and sufficient for risk assessment. In an acute oral toxicity study male and female Wistar rats were dosed once with 5000 mg/kg bw 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (Takagi 1994). The test substance suspended in olive oil (30% w/v) was administered to 5 male and five female rats. Toxic signs and mortality were monitored for 9 hrs on the day of administration and then twice a day up to day 14 when the test was terminated. Body weights were recorded at days 3, 7, 10 and 14 after administration. No mortality occurred during the study. Diarrhoea was observed 1 h after the administration of the test material or vehicle alone (controls). Diarrhoea disappeared within 1 day (controls) or 6 days (treatment group). No other clinical signs were indicated. In both sexes, no significant differences in body weight gain was observed between control and treated rats. An oral LD50 value greater 5000 mg/kg bw was suggested.

In another early acute oral toxicity study with male Albino rats (American Cyanamid Company 1965) an oral LD50 value greater than 10000 mg/kg bw was suggested. Further studies with rats and mice confirmed the very low acute oral toxicity of 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol indicated by LD50 values greater than 5000 mg/kg bw (Hagan 1952, Garlanda 1962, Stasenkova 1977).

Acute toxicity: dermal

The acute dermal toxicity of 6,6’-di-tert-butyl-2,2’-methylendi-p-cresol (DBMC) was evaluated in an early toxicity study with male albino rabbits (American Cyanamid Company 1965). However, the study design and documentation are not inline with current guidelines but the study is acceptable well-documented and sufficient for risk assessment. Five male rabbits were exposed with 10000 mg/kg test substance for 24 hours, followed by a 14day-observation period. No mortality and clinical signs occurred during the study (0/5). No skin irritation was observed. Gross autopsy performed at study termination revealed no abnormalities. Based on the findings of this study the authors suggested a dermal LD50 greater than 10000 mg/kg bw.

Justification for classification or non-classification

No classification is required according to the classification criteria 67/548/EWG and regulation no. 1272/2008 (GHS).