1,2,3-Propanetriol, mono- and diformates

Toxicity to aquatic algae and cyanobacteria

Description of key information

EC50 (72 h) ethylene glycol diformate: 38 mg/L for Pseudokirchneriella subcapitata based on growth rate (nominal; OECD 201), corresponding to 38.6-47.7 mg/L 1,2,3-propanetriol, mono- and diformates. 
NOEC (72 h) ethylene glycol diformate: 10 mg/L for Pseudokirchneriella subcapitata based on growth rate (nominal; OECD 201), corresponding to 10.2-12.5 mg/L 1,2,3-propanetriol, mono- and diformates.

Key value for chemical safety assessment

EC50 for freshwater algae:

38.6 mg/L

EC10 or NOEC for freshwater algae:

10.2 mg/L

Additional information

One experimental study investigating the effects of ethylene diformate (CAS 629-15-2) on freshwater algae is available (Vryenhoef, 2013). The study was performed according to OECD guideline 201 under GLP conditions using the freshwater alga Pseudokirchneriella subcapitata. Nominal test substance concentrations up to 100 mg/L were applied. The substance was found to hydrolyse in test medium with an approximate half-life of 4 h. The analytical measurement with gas chromatography (GC) revealed a decline in test concentrations. Therefore, the possible effects of the parent substance and the hydrolysis products were assessed in this study. After an exposure of 72 h an EC₅₀ (72 h) of 38 mg/L and a NOEC (72 h) of 10 mg/L were calculated based on growth rate. Complete hydrolysis of the parent test item did not occur and toxicity cannot be attributed to the parent test item, the hydrolysis product or a mixture of the two. Therefore, it was considered appropriate to calculate the results based on nominal parent test item concentrations only.

The result for ethylene glycol diformate is used for the assessment of the substance 1,2,3-propanetriol, mono- and diformates in a read-across approach (for details and justification please refer to the read-across report).

The EC₅₀ of 38 mg/L ethylene glycol diformate (M = 118.1 g/mole) corresponds to 38.6-47.7 mg/L 1,2,3-propanetriol, mono- and diformates (M = 120.1-148.11 g/mole). The NOEC of 10 mg/L ethylene glycol diformate corresponds to 10.2 -12.5 mg/L 1,2,3-propanetriol, mono- and diformates.

In addition, available data on sodium formate are used as supporting information for the following reasons:

1,2,3-propanetriol, mono- and diformates is used as an acidity regulator in textile treatment baths. Due to rapid hydrolysis release of this substance to wastewater (and further to the environment) is essentially zero. The substance is added to treatment baths of basic pH, and consequently shifts the pH to neutral or slightly acidic values. In the technical process (textile treatment) the substance reacts completely, yielding glycerol and formic acid/formate. The relevant breakdown product to be considered in the risk assessment hence is formic acid in dissociation equilibrium with formate. Glycerol is of no environmental concern and does not require to be assessed. Also the formate ion is not environmentally hazardous as demonstrated by the acute 72-h LC₀ for aquatic freshwater algae (Desmodesmus subspicatus) of > 1000 mg/L. In the relevant pH range (approximately neutral) the equilibrium is shifted towards the free formate. Use of data on sodium formate is therefore justified.