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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

Urea is of very low acute toxicity to fish. Phosphoric acid showed a median lethal pH (96h) 3-3.25 for Lepomis macrochirus (no guideline followed).
When adjusted to environmentally relevant pH values, phosphoric acid does not cause acute adverse effects.

Key value for chemical safety assessment

LC50 for freshwater fish:
9 100 mg/L

Additional information

Urea phosphate will dissociate into urea and phosphoric acid in aqueous environment.

Urea is of very low acute toxicity to fish. The 96 hour LC50of urea to B. barna was > 9100 mg/L, the LC50 for 72 -hr was 12100 mg/L. The NOEL was 4961 ppm. More values were reported, however these studies had a less exposure time, showed a higher LC50 or not a fixed value.

The study from Ellgaard and Gilmore 1982, focuses on the pH effects caused by phosphoric acid. Different pH levels have been tested in bluegill sunfish. The pH induced by phosphoric acid which caused 50% mortality was between 3.0 and 3.25, while no mortality was observed at pH 3.5 or above after 96h exposure. At neutral pH 7.5 no fish died. The same is seen in more less reliable studies. As regulatory ecotoxicity tests need to be conducted at pH 6-9, it can be expected that phosphoric acid will not cause adverse effects to fish when in this pH range.