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

Endpoint summary

Additional information

Acute tests evaluating the toxicity of ethylene diformate (CAS 629-15-2) to aquatic organisms from three different trophic levels are available.Since the substance is susceptible to abiotic hydrolysis (DT₅₀: 1.24 d (pH7) and 2.98 h (pH8) (HYDROWIN v2.00)) it is likely that the possible effects of the parent substance as well as the hydrolysis products were assessed in the available studies. Further analytical investigations in the available ecotoxicological studies resulted in DT₅₀ values of 4 h in standard algae medium (OECD 201; Vryenhoef, 2013) and 11 h in standard daphnia medium (OECD 202; Vryenhoef, 2012).

In the available studies aquatic algae turned out to be the most sensitive species (EC₅₀, 72 h: 38 mg/L). No short-term toxicity to aquatic invertebrates was observed, resulting in an EC₅₀ (48 h) > 100 mg/L (nominal). The short-term toxicity study to fish (OECD 203) revealed that fish are slightly less sensitive (LC₅₀, 96 h = 42 mg/L).

Ethylene diformate is readily biodegradable. Moreover, the test substance caused no inhibition of biodegradation and was not toxic to the inoculum in a toxicity control included in a standard biodegradation study according to OECD 301B (NOEC ≥ 28.4 mg/L). Therefore, inhibition of the subsequent degradation process in sewage treatment plants is not expected.

This result on 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 above mentioned toxicity values for ethylene diformate correspond to the following concentrations of 1,2,3-propanetriol, mono- and diformates:

- Oncorhynchus mykiss, LC₅₀ (96 h) = 42.8-52.7 mg/L

- Daphnia magna, EC₅₀ (48 h) > 101.7-125.4 mg/L

- Pseudokirchneriella subcapitata, E_rC₅₀ (72 h) = 38.6-47.7 mg/L

In addition, one experimental study investigating the inhibition of respiration of diethylene glycol diformate (CAS 120570-77-6) to activated sludge microorganisms is available (Roulstone, 2012). The study was conducted according to OECD 209 under GLP conditions using activated sludge from a sewage treatment plant treating predominantly domestic sewage. Five concentrations up to 1000 mg/L (nominal) were tested. After 3 h contact time diethylene glycol diformate resulted in an EC₁₀ of 580 mg/L based on the respiration rate.

These results for diethylene glycol diformate are 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 EC₁₀ of 580 mg/L diethylene glycol diformate (M = 162.14 g/mole) corresponds to ca. 430-530 mg/L for 1,2,3-propanetriol, mono- and diformates (M = 120.1-148.11 g/mole).

Furthermore, 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. Release of this substance to wastewater (and further to the environment) from this use 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 acute LC₅₀ and/or NOEC values invariably > 1000 mg/L (see IUCLID sections 6.1.1–6.1.3). In the relevant pH range (approximately neutral) the equilibrium is shifted towards the free formate. Use of data on sodium formate is therefore justified. The effect data demonstrate that sodium formate is not hazardous to the environment, hence need not be assessed quantitatively. Therefore, despite almost complete hydrolysis PEC and PNEC of the parent substance 1,2,3-propanetriol, mono- and diformates, are compared. This applies to uses resulting in complete hydrolysis of the substance due to the technical function (see CSR).

The environmental exposure assessment for 1,2,3-propanetriol, mono- and diformates according to Annex XI, section 3 indicates no risk for the aquatic compartment (all RCR < 1; please refer to chapters 9 and 10 of the chemical safety report for detailed information). Thus, long-term testing with aquatic invertebrates and fish is not deemed necessary.