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Description of key information

Several acute toxicity studies were performed with tributyl phosphate - but only a few can be used for assessment due to insufficient reporting.
In the key study for acute oral toxicity a LD50 = 1553 mg/kg bw was found in rats. This value was supported by another study in rats were a a LD50 = 1400 mg/kg bw was determined.
In the key study for acute dermal toxicity a LD50 > 3100 mg/kg bw (highest applied dose) was notified.
Acute inhalative toxicity was tested with the test substance in male and female Wistar rats(key-study). The doses tested for 4 hours were: 0; 511; 801; 2140; 4242 mg/m³ air. After 4242 mg/m³ air 2 of 5 male rats died; the female rats in this dose group showed no mortalities.
The LD 50 was approx. 4242 mg/m³ air in the the more sensitive male rat. The available acute toxicity studies for other routes were no assignable.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
1 553 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion
Dose descriptor:
LC50
Value:
4 242 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion
Dose descriptor:
LD50
Value:
3 100 mg/kg bw

Additional information

Tributyl phoshate was harmful by inhalation and if swallowed. In the key study for acute oral toxicity a LD50 = 1553 mg/kg bw was found. In the key study for acute inhalation toxicity a LC50 = 4242 mg/m³ (2/5) for male rats and LC50 > 4242 mg/m³ (0/0) for female rats was determined. By dermal application tributyl phosphate was only slightly toxic.

Justification for classification or non-classification

A LD50 = 1530 (oral, rat, male) was found in a valid study, therefore a classification Xn, R22 (GHS: 3.1, Category 4, H203) is justified.

For inhalation a LC50 = 4242 mg/m³ (inhalation, rat, male) and LC50 > 4242 mg/m³ (inhalation, rat, female) was determined. In summary 2/10 rats (combined males and females) died at this concentration (highest applied dose). A classification by inhalation is therefore not justified.

A classification by dermal absorption is not justified.