Phosphorus trichloride

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.1 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

Additional information

Four aquatic toxicity studies have been conducted with phosphorus trichloride.

Fish were exposed to a control or a nominal phosphorus trichloride concentration of 1000 mg/L for a period of 96 hours, mortalities after 24, 48 and 72h were recorded. No mortalities were observed, therefore the 96 hour LC₅₀was observed to be >1000 mg/L (based on the nominal exposure concentration). A 48 hour acuteDaphniatoxicity study (conducted according to OECD Guideline Method No 202) was conducted exposing phosphorus trichloride toDaphnia magna. The results of the study are based on nominal exposure concentrations and on test media without pH adjustment. The 24 and 48 hour EC₅₀was 35.4 mg/L (geometric mean EC₀/EC₁₀₀). Under pH adjusted conditions no inhibition of growth has been observed at a nominal concentration of 100 mg/L. A 72 hour algal study (conducted according to EU Method C.3 (Algal Inhibition test)) was conducted exposing phosphorus trichloride toDesmodesmus subspicatus. The results of the study are based on nominal exposure concentrations and on test media without pH adjustment. The 72 hour E_bC₅₀was 30.24 mg/L (95% confidence limits of 29.99 to 30.49 mg/L), the 72 hour E_rC₅₀was 33.41 mg/L (95% confidence limits of 33.25 to 33.57 mg/L) and the overall NOEC was 12.5 mg/L. Under pH adjusted conditions, no inhibition of algal growth was observed at a nominal concentration of 100 mg/L. Five concentrations of phosphorus trichloride (1000, 1800, 3200, 5600 and 10000 mg/L) were assessed for their effect on activated sludge by measuring the respiration rate and % inhibition. The resulting EC₅₀was calculated to be 9450 mg/L. In all studies, analytical determination of test substance concentration was not performed due to its rapid reaction with water and subsequent degradation. The results of the studies indicate that the aquatic toxicity of the substance is due to pH changes in the exposure medium due to the degradation products hydrochloric and phosphoric acid.

Conclusion on classification

Phosphorus trichloride is listed on Annex I of Directive 67/548/EEC with no classification for environmental effects. No change to this classification is proposed on the basis of the data evaluated.