Reaction products of sulphuric acid, rock phosphate and humic acids, potassium salts

Short-term toxicity to fish

Description of key information

In an OECD 203 study (Madsen 2000), performed under GLP conditions, with the surrogate substance Monoammonium Phosphate no mortality was observed and the 96-hour LC50 value was determined to be >85.9 mg/L (>100 mg/L nominal), the highest treatment concentration tested. 
In an OECD 203 study (under GLP conditions) calcium sulfate dihydrate was tested for acute toxicity to Oryzias latipes. As no mortalities were observed at the test concentration of 100 mg/L the LC50 was determined to be >100 mg/L. Also, in a study according to EU method C.1 (GLP) with potassium humate no mortality or other signs of toxicity were observed in guppy fish . The LC50 in this study was >128 mg/L.

Additional information

The following information on constituents of the submission substance and components of the humate-complexed superphosphate are available:

Phosphate (monoammonium phosphate):

In an OECD 203 Guideline study (Madsen 2000), performed under GLP conditions, acute toxicity to fish of the surrogate substance Monoammonium Phosphate at nominal test concentrations of 6.25, 12.5, 25.0, 50.0, and 100 mg/L (measured concentrations: 5.72, 11.9, 23.5, 46.6, and 85.9 mg/L) was tested. No deviations from guideline were noted and the study was considered to be valid and of high quality, but information on purity of the test item is lacking (reliability 2).

No mortality was observed under the conditions of the test. Based on mean calculated total product test concentrations of Monoammonium Phosphate in test water, the 96-hour LC50 value was determined to be >85.9 mg/L (>100 mg/L nominal), the highest treatment concentration tested. 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. On a phosphate basis this amounts to an equal concentration of Ca(H₂PO₄)₂.

Potassium humate:

In a guideline study according to EU method C.1 (Roupcova 2007), performed under GLP conditions, acute toxicity to fish of the surrogate substance humic acid, potassium salt was investigated. No mortality or signs of abnormal behaviour were observed in guppies up to the highest concentration tested. Therefore, the LC50 - 96 h in this study was > 128 mg/L.

Ca sulfate:

In the publication by Mount et al. (1997) various solutions of inorganic salts were tested towards fish (fathead minnows, Pimephales promelas) and daphnids. The study is well documented and followed US EPA guidelines. An 96 h LC50 of >1970 mg/L was obtained for Ca-sulfate with Pimephales promelas.

In a study (limit test) according to OECD 203 (under GLP conditions) calcium sulfate dihydrate was tested for acute toxicity to Oryzias latipes. As no mortalities were observed at the test concentration of 100 mg/L the LC50 was determined to be >100 mg/L.

Taken these data together this shows that the submission substance, consisting of the humate phosphate complex and Ca sulfate does not possess aquatic toxicty to fish. An LC50 of > 86 mg/L can be deduced from the data.