Phosphine

Endpoint summary

Description of key information

The acute inhalation of phosphine is high. Four-hour LC50 value between 26.5 ppm (37.5 mg/m3) and 33.4 ppm (47.3 mg/m3), for mice, has been reported (Omae et al., 1996). For rat, different LC50 values have been reported: 28 ppm (39.7 mg/m3)/5.2 hours (Newton et al., 1993) and 11 ppm (15.6 mg/m3)/ 4 hours (Waritz and Brown, 1975). 
Early symptoms of acute phosphine exposure include respiratory problems, dizziness, general fatigue and gastrointestinal disturbance.
The effects on mice and on rat seem to be equivalent. 

Key value for chemical safety assessment

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

37.5 mg/m³ air

Additional information

All the studies mentioned hereafter have been performed using whole-body exposures of animals to phosphine.

Omae et al. (1996) determined a 1-hour LC50 >59.2 ppm (the highest concentration tested), and a 4-hour LC50 was between 26.5 and 33.4 ppm in male mice. Newton et al. (1993) defined a 6-hour LC50 of 28 ppm for male and female Sprague-Dawley rats. Muthu et al. (1980) calculated a 5.2 hours LC50 of 28 ppm and LC95 values of 45 ppm and 33.3 ppm for 6.2 -h and 8.8 h, respectively, in female albino rats. Signs of respiratory irritation, including hyperemia of the ears, salivation, lacrimation, face pawing, and dyspnea were observed in rats during this study. A 4-hour LC50 of 11 ppm of phosphine was reported for male rats (Waritz and Brown, 1975). The concentration×time products from these data are relatively constant across species except for the Waritz and Brown (1975) data, which appear to be an outlier.

Clinical signs in mice included facewashing movements, increased activity in the initial exposure period, followed by a slowing in response to tapping on the chamber glass, supine posture, slight tremor, piloerection, mild loss of spontaneous motor activity progressing to complete loss of motor activity, ocular cloudiness, and moribundity.

Exposure to phosphine affected multiple endpoints in rats and mice. Rats exposed for 6 hours exhibited increased hematology values at 12 and 18 ppm; decreased body weight at 12, 18, and 26 ppm; and tremors, hunched appearance, decreased activity, and death at 26 ppm (Newton et al. 1991). Rats exposed to 2.5, 5.0, or 10 ppm of phosphine for 6 hours exhibited a red nasal discharge (Newton et al. 1993).

Justification for classification or non-classification

Phosphine is listed on Annex VI to Regulation (EC) No 1272/2008 includes lists of harmonised classification and labelling.

On table 3.2 (classification and labelling in accordance with the criteria set up in Annex VI to Directive 67/548/EEC),, phosphine is listed with very toxic R26 (T+ , very toxic by inhalation) and corrosive R34 (C, causes burns) classification. No change to this classification is proposed.

On table 3.1(classification and labelling in accordance with the criteria set up in Annex I to the Regulation), phosphine is listed with Acute Tox. Category 2 H330 (fatal if inhaled) and Skin Corr category 1B H314 (causes severe skin burns and eye damage) classification. On the basis of the LC50 values and the concentration-time product, a change is proposed on the Acute category. The new acute classification is Acute Tox. Category 1 H330 (Fatal if inhaled). No change is proposed for Skin Corr. Category 1B H314 (causes severe skin burns and eye damage).