Phosphorus

Endpoint summary

Description of key information

The substance (white phosphorus) is highly toxic to fish in laboratory studies, however in the environment it is likely that dissolved elemental phosphorus will be rapidly oxidised to phosphates and phosphorus oxides which will be of much lower toxicity.

Short-term toxicity to fish

The acute toxicity of dissolved elemental phosphorus to cod (Gadus morhua) was investigated in the absence of colloidal phosphorus. The 48 h LC50 for dissolved elemental phosphorus is 14·4 μg/L, and evidence is presented that the incipient lethal level is ca. 1–2 μg/L. Elemental phosphorus was rapidly assimilated into the body tissues of the test animals. The distribution of phosphorus was homogeneous in the muscle tissue with levels ca. 10–30 times the exposure level, highest concentrations were measured in the liver (Maddock & Taylor, 1976).

In a literature review, Burrowset al(1973) conclude that white phosphorus is highly toxic to fish. The 96 hour LC50 values are less than 50 ppb for all fish species studied, and it is noted that the incipient lethal level is 'probably less than 1 ppb' for most fish. Phosphorus poisoning appears to be cumulative and irreversible, though the cause of mortality has not been determined. While phosphorus is readily taken up by fish and other aquatic organisms directly from the water, fish may also acquire lethal quantities of elemental phosphorus through the food chain, since the few macroinvertebrates studied have a much higher tolerance for white phosphorus than fish. The symptoms of phosphorus intoxication are passed onto brook trout when they are fed muscle tissue from phosphorus-poisoned cod. The authors postulate that that the minimum 'incipient lethal level' is 0.1 ug/l, comparable to the NOEC, (1/5 the lowest measured).

In a study of dietary toxicity (Fletcher, 1973), brook trout (Salvelinus fontinalis) were exposed to P4 in the diet (cod muscle, cod liver). The approximate toxic dose of P4 ranged from 1.23- 2.73 mg.

Short-term toxicity to aquatic invertebrates

 

No data are available: a waiver is proposed for this endpoint. White phosphorus is of limited water solubility (3 mg/L) and the solubilised substance is rapidly oxidised to phosphate. It is well documented that phosphates are critical nutrients required for the growth of algae, a food source for aquatic invertebrates such as Daphnia. Low aquatic concentrations of phosphate resulting from white phosphorus will stimulate the growth and reproduction of aquatic invertebrates as a consequence of the effects on their food source. Higher concentrations of phosphate are unlikely to be achieved due to the low water solubility of white phosphorus, but have the potential to cause adverse effects as a consequence of teh stimulation of excessive algal growth and subsequent eutrophication.

Short-term toxicity to algae

No data are available: a waiver is proposed for this endpoint. White phosphorus is of limited water solubility (3 mg/L) and the solubilised substance is rapidly oxidised to phosphate. It is well documented that phosphates are critical nutrients required for the growth of algae and other aquatic plants. Low aquatic concentrations of phosphate resulting from white phosphorus will stimulate the growth of algae. Higher concentrations of phosphate are unlikely to be achieved due to the low water solubility of white phosphorus, but have the potential to cause adverse effects as a consequence of the stimulation of excessive algal growth and subsequent eutrophication.