Reaction mass of Ammonium dihydrogenorthophosphate and diammonium hydrogenorthophosphate.

Short-term toxicity to fish

Description of key information

Based on a reliable study with ammonium dihydrogenorthophosphaten the LC50 for freshwater fish (rainbow trout) is > 85.9 mg/L. Based on a reliable study with diammonium hydrogenorthophosphat the LC50 for freshwater fish is determined to be 1700 mg/L. As the result, by analogy with its constituents, reaction mass of ammonium dihydrogenorthophosphate and diammonium hydrogenorthophosphate should not show any adverse effects on fish.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 700 mg/L

Additional information

In a reliable OECD 203 guideline study, rainbow trout were exposed for 96 hr under static conditions to 6.25, 12.5, 25.0, 50.0, and 100 mg/L ammonium dihydrogenorthophosphate. Measured concentrations were determined to be 5.72, 11.9, 23.5, 46.6 and 85.9 mg/L (mean of t=0 and 96 h; 86 to 95% of nominal concentration). Based on mean calculated total substance concentrations in test water, the 96-hour LC50 value was determined to be >85.9 mg/L (>100 mg/L nominal), the highest treatment concentration of the definitive test. The 96-hour NOEC was =85.9 mg/L, based on the absence of any mortality and sublethal effects at this and all lower treatment concentrations. The slope of the 96-hour dose-response line could not be calculated due to the absence of mortality.

In a reliable study performed according to "Standard Methods for the Examination of Water and wastewater (APHA-1985)", freshwater fish of the carp family (Cirrhinus mrigala/L. Rohita), fry and fingerlings were exposed to diammonium hydrogenorthophosphate under static conditions with different temperatures. The toxicity of the substance to fish increased with increasing water temperature. According to OECD 203 the recommended temperature for common carp is between 20 -24°C, therefore the LC50s found at this temperature was taken. LC50 (fry; 21°C) = 1700 mg/L, LC50 (fingerlings; 21°C) = 1875 mg/L.

Based on these data on the constituents, the reaction mass of ammonium dihydrogenorthophosphate and diammonium hydrogenorthophosphate should not show any adverse effect on fish. As test items are dissolved in water during aquatic toxicity tests, a similar conclusion can be drawn out for both forms of the reaction mass (i.e. solid and liquid).