Triethyl phosphite

Endpoint summary

Description of key information

In a skin irritation study (OECD TG 404, no GLP) no irritating effect of the test substance was observed in 6 albino-rabbits. In a study (OECD TG 405, no GLP) in 3 male rabbits no eye irritating effects of the test substance have been observed. Due to signs of irritation in an acute inhalation toxicity study and a sensitizing effect of the test substance a respiratory irritation can not be excluded.

Additional information

Skin irritation

A study according to OECD guideline 404 (adopted 1981) employing 6 female albino-rabbits revealed slightly irritating effects on the skin after 4 hours of semi-occlusive exposure to the undiluted test substance. All animals showed slight or clearly visible erythema at the treated sites up to 48 hours after exposure (grade 1 or 2). At day 7, slight erythema (grade 1) still persisted in 5 animals, but had resolved in all but one animal at day 10. None of the animals showed edema at any of the observations (Bayer AG, 1983). No raw data were available to calculate the mean erythema and edema scores over 24, 48, and 72 hours. But the given information together with the fact that all erythema reactions were fully reversible within 10 days and no edema reaction was observed at all leads to the conclusion, that the mean scores (24, 48, and 72 hours) were smaller than 2. Data from a Draize test confirm this result (Kinkead et al., 1992). After semi-occlusive treatment of intact skin of New Zealand White rabbits for 4 hours a dermal irritation index of 1.7 was reported, leading to the conclusion that erythema and edema mean values over 24, 48, and 72 hours have been smaller than 2.

Results from an acute dermal toxicity study where rats were treated with up to 954 mg/kg bw for 2 hours revealed no signs of irritation (Bayer AG, 1959). Furthermore no skin reactions have been observed in a sensitization study, 48 h after occlusive epicutaneous challenge of the control group with 100% test substance.

Eye irritation

A study according to OECD guideline 405 was performed and revealed slightly irritating effects on the eyes of 3 male rabbits. All animals showed slight or clearly visible conjunctival erythema in the treated eyes (grade 1 or 2). Slight chemosis and increased secretion were recorded in two animals, each. The findings appeared within one hour and were completely reversible within 48 hours. A conjunctivae mean score out of all 3 animals of 0.2 (24, 48, and 72 h) was deduced. No effects were noted in corneae and irises at any observation point (Bayer AG, 1959). Another study employing 9 rabbits (6 eyes unwashed and 3 washed) showed moderate but quickly reversible (within 48 hours) irritating effects on the eyes. Effects were more severe after washing with water (Kinkead et al., 1992). This is in concordance with observations of a 6-hour inhalation study with up to 11.6 mg/L triethyl phosphite where eye irritation was observed, but was fully reversible within the observation period (Kinkead, 1992).

Respiratory irritation

There exists no standard test method for the assessment of respiratory irritation. Thus, findings for skin/eye irritation and acute inhalation toxicity are reviewed. The test substance has been shown to be slightly irritating to the skin and the eyes (fully reversible within the observation period). Results from an acute 6 -hour inhalation study revealed signs of toxic stress including eye and upper respiratory irritation, salivation and rapid, shallow breathing. Surviving animals appeared normal to conclusion of observation period. Pathological observations in the dead animals revealed diffuse lung congestion. In conclusion, it can not be excluded that triethyl phosphite is an irritant to the respiratory tract based on the current information. Human data or animal data from repeated inhalation toxicity studies are not available for further assessment of respiratory irritation.

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

-No classification required for skin and eye irritation/corrosion.

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

- Skin corrosion/irritation: no classification required

- Serious eye damage/eye irritation: no classification required

- Specific target organ toxicity, Single exposure: no classification required