Triethyl phosphite

Endpoint summary

Description of key information

Acute toxicity, oral, rat (No GLP, no guideline study): LD50 = 2470 mg/kg bw (males), 1840 mg/kg bw (females)
Acute toxicity, dermal, rabbit (No GLP, no guideline study): LD50 = 2800 mg/kg bw (males), >3000 mg/kg bw (females)
Acute toxicity, inhalation, rat, aerosol (No GLP, no guideline study): LC50 = 11.6 mg/L (males), 11.1 mg/L (females)

Additional information

All data discussed in the endpoint summary for acute toxicity were derived from a secondary source (OECD SIDS, 2003).

Acute toxicity, oral

Data for acute toxicity after oral administration were available from rats and mice. None of the studies were performed according actual guidelines and under GLP. In the key study with male and female Fisher 344 rats, triethyl phosphite was administered at doses from 1000 to 4000 mg/kg bw. Symptoms of rapid breathing and tremors were observed prior to death. The calculated LD50 was 2470 mg/kg bw for males and 1840 mg/kg bw for females (Kinkead et al., 1992). In a supporting study an LD50 of > 2385 mg/kg bw was observed in male rats. No clinical symptoms and mortality were observed at the dose level of 2385 mg/kg bw (Bayer AG, 1959).

In the mouse the toxicity of triethyl phosphite after oral administration was determined by Kinkead et al. (1992). The dose range was from 2000 to 5000 mg/kg bw and the LD50 was determined as 3720 mg/kg bw for males and 3800 mg/kg bw for females. Rapid breathing and tremor were observed in the animals prior to death. No quantitative data regarding dose-response curves were reported in any study.

Acute toxicity, dermal

In the key study 5 New Zealand White rabbits per sex and dose were exposed to doses of 2000, 2500, and 3000 mg/kg bw. The 24 h occlusive application of triethyl phosphite on 30% of the body surface led to an LD50 of 2800 mg/kg bw in males and an LD50 of > 3000 mg/kg bw in females (Kinkead et al., 1992). Clinical signs of toxicity were not reported.

Acute toxicity, inhalation

Two studies were available where each 10 male and female Fisher 344 rats and CD-1 mice per dose were exposed to an aerosol of the test substance with a MMAD of 1.6 - 3.5 µm for 6 hours. A LC50 of 11.6 mg/L for male and 11.1 mg/L for female rats and a LC50 of 6.2 and 9.2 mg/L for male and female mice was deduced, respectively. In both species, signs of toxic stress included eye and upper respiratory irritation, salivation and rapid, shallow breathing; most deaths occurred within 24 hours following treatment. No quantitative data regarding the dose-response curve were reported in the studies (Kinkead et al., 1992).

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

-Classification required for acute toxicity: Xn, R22

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008:

-Oral route: Classification in Category 4

-Inhalation route: no classification required

-Dermal route: no classification required