Formic acid

Toxicity to aquatic algae and cyanobacteria

Description of key information

With high probability not acutely harmful to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

1 000 mg/L

EC50 for marine water algae:

1 000 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

EC10 or NOEC for marine water algae:

560 mg/L

Additional information

Data on growth inhibition of aquatic algae are available from studies performed with ammonium formate (1 study) and potassium formate (2 studies, 1 with a marine algae species) ( Kemira Oyi, 1992&2005; Osca 1994). The 72 -h EC₅₀values are all > 100 mg/L. In conclusion, no harmful effects to aquatic algae are to be expected.

Regarding the NOEC values, the results with potassium formate indicate that the NOEC is > 500 mg/L. With ammonium formate, a NOEC for the relevant endpoint "growth rate" is not given in the study report. However, from the available data it can be seen that at the lowest concentration (76.8 mg/L) the inhibition of the growth rate is 3.4 % and at the next higher concentration (192 mg/L) it is 7.2 %, respectively. It cannot be verified whether this slight inhibition is significantly different from the control. However, taken the results with potassium formate into account, inhibition of the algae growth rate due to formate exposure is not expected at concentrations of 100 mg/L or below. A NOEC of 100 mg/L is assumed for the formate ion.

Regarding the marine diatom Skeletonema costatum an EC50 (72h) > 1000 mg/l and a NOEC of 560 mg/L were found with potassium formate liquor of unknown purity.