Methyl formate

Toxicity to aquatic algae and cyanobacteria

Description of key information

The parent compound methyl formate along with its hydrolysis products formic acid and methanol are with high probability acutely not harmful to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

1 062 mg/L

EC10 or NOEC for freshwater algae:

131.2 mg/L

Additional information

Parent compound (CAS 107-31-3)

Data on growth inhibition of aquatic algae are available from two static studies without analytical test item verification performed according to the German Industrial Standard DIN 38412 Part 9. The data of the original reports were re-evaluated using ToxRat v2.09 in order to obtain an EC10, which is originally not reported. According to REACH Guidance document chapter R.10 Table R.10-1 (Overview of toxicity test endpoints and guidance on derivation of L(E)C50 and NOEC values) an EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially. In the first study the 72 -h ErC50 of 1079 mg/L and the 72-h ErC10 of 131.2 were calculated (original report: nominal, BASF AG, 1989; re-calculation: ECT GmbH, 2006). In the second study the study the 72 -h ErC50 of 1062.7 mg/L and the 72-h ErC10 of 140.7 were calculated (original report: nominal, BASF AG, 1988; re-calculation: ECT GmbH, 2006). In addition, the validity criteria and required test parameters of the current guideline were compared to those of the older guideline version.

Moreover, according to the available hydrolysis study for the substance, Methyl formates' susceptibility to hydrolysis increases with pH as well as with temperature. The hydrolysis half-life ranges from 410 h at pH 4 and 20 °C to less than 1 hour at pH 9 and 25 °C (OECD 111, BASF SE, 2010). Therefore, it can be concluded, that under environmentally relevant conditions (pH 7-9) the rapid hydrolysis will be the major fate process of the methyl formate due to the short half-life in aqueous solution. Therefore, this estimate may be of low relevance. Thus, the assessment of the toxicity of the substance is also based on the available experimental data for the hydrolytic products: formic acid and methanol.

 

Hydrolysis product formic acid (CAS 64-18-6):

Data on growth inhibition of aquatic algae are available from a GLP guideline study performed with the freshwater species Pseudokirchnerella subcapitata. An 72h-EC10 of 295 mg/L along with the 72-h EC50 of 1240 mg/L are assumed for the ammonium formate (nominal, analytically verified, Fraunhofer, 2005, KEM-001/4-30).

The ammonium formate is a salt of the hydrolysis product formic acid. Formic acid changes the pH of the test solutions towards acidic conditions. When using ammonium salt as a test substance, the pH is not affected. Therefore, both substances are suitable to investigate the sensitivity of fish towards formic acid under pH-neutralised conditions.

Hydrolysis product methanol (CAS 67-56-1):

In a 96 -h test with Pseudokirchneriella subcapitata following OECD TG 201 an EC50 of 22000 mg/L based on growth rate was determined (nominal, Cho et al., 2008).

 

Overall, based on the available experimental data it can be concluded, that the parent compound methyl formate along with its hydrolysis products formic acid and methanol are with high probability acutely not harmful to algae.