Ammonium acetate

Toxicity to aquatic algae and cyanobacteria

Description of key information

Toxicity to aquatic algae and cyanobacteria: Weight of evidence: Read-across approach from experimental results obtained with analogues Acetic Acid, Potassium Acetate and Ammonium Sulphate. The (72 h) EC50 is calculated to be > 392.70 mg/L and the NOEC is 392.70 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

392.7 mg/L

Additional information

Weight of evidence:

Read-across approach from experimental results obtained with analogues Acetic Acid, Potassium Acetate and Ammonium Sulphate.

In the first publication, reported by Bringmann and Kühn (1980), using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of Acetic Acid was determined for green algae of the species Scenedesmus quadricauda. The concentration of the algal suspension was measured turbidimetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness. The test temperature was 25 ºC. Toxicity threshold is defined as the pollutant concentration resulting in a mean extinction value that is ≥ 3% below the mean of the extinction value for the nontoxic dilutions of the test culture). The toxicity threshold of Acetic acid for Scenedesmus quadricauda was 4000 mg/L.

The read-across approach is applied and the Toxicity Threshold for Ammonium Acetate is calculated to be 5138.67 mg/L.

In the second study, a Skeletonema costatum acute toxicity test (72 hours) was performed on the test substance Safeway KA HOT (50 % water solution of Potassium Acetate) based on ISO 10253 “Water Quality Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactum tricornutum”. The 72 hours EC₅₀value for the test substance was found to be > 1000 mg/L (for Potassium acetate was > 500 mg/L). The NOEC value was estimated to 1000 mg/L (500 mg/L for Potassium acetate).

The read-across approach is applied and the EC50 for Ammonium Acetate is calculated to be > 392.70 mg/L, and NOEC is calculated to be 392.70 mg/L under test conditions.

In the third publication, reported by Tam and Wong (1996), in a long term test, the green algae Chlorella vulgaris were exposed to Ammonium Sulfate for 21 days at concentrations of 10-1000 mg N/L. In control medium, the N-source was KNO3, which was replaced by different concentrations of ammonium sulfate in the test media (47 - 4710 mg/L ammonium sulfate, calculated from 10 – 1000 mg/L NH3-N). The pH value was adjusted to 7 ± 0.2 before algae inoculation and was maintained at neutral pH during the study.

In the first, 10 days after start, in all test concentrations and in the control a lag phase was observed. Thereafter in the control and in some test concentrations an exponential increase in cell number was observed up to day 17 or 18. In the 21-day test with Chlorella vulgaris exposured to ammonium sulfate, an EC50 of ca. 25476 mg/L (ca. 2700 mg NH3/L) was established from exponential growth on day 11-18.

The read-across approach is applied and the EC50 for Ammonium Acetate is calculated to be ca. 29721.36 mg/L under test conditions.

Tha critical study for this endpoint is considered the ECOSAR Calculation. The result is between the value for read-across from Ammonium Sulfate and Acetic Acid and Potassium Acetate and fits between the results. The value is high but still lower than the water solubility of the substance.

ECOSAR v1.00 calculation for Ammonium acetate: EC50 for Green Algae, 96 hours is 16019.335 mg/L.