Methyl formate

Adsorption / desorption

Description of key information

Adsorption of methyl formate and its hydrolysis products (methanol and formic acid) to the solid soil phase is not expected.

Additional information

Parent compound (CAS 107-31-3)

In order to assess the adsorption potential of the parent compound methyl formate (CAS 107-31-3), the Koc value was estimated using QSAR models (BASF SE, 2021). According to the MCI method of the KOCWIN v2.00 module of EPI Suite v4.11 the substance has a Koc of 1.99 L/kg (log Koc = 0.301). The estimation of the MCI module is more reliable than the log Kow method of KOCWIN v2.00, which estimates the Koc based on the substance’s n-octanol/water partition coefficient (measured log Kow = -0.21; see ICULDI Ch. 4.7). The latter method resulted in a Koc of 5.54 L/kg (log Koc = 0.74); the substance is within the applicability domain of both estimation models.  

Based on the estimated data, adsorption to the solid soil phase is not to be expected.

However, 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. The adsorption potential will, therefore, be also assessed based on information available for the hydrolysis products methanol and formic acid.

 

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

Adsorption on soil is not to be expected due to the high solubility of the formic acid as well as its low octanol-water partition coefficient. Aditionally, the adsorption of formic acid was tested in the GLP study, conducted according to OECD 121. In this study the log Koc value was determined to be lower than 1.25 (BASF, 2002, Study No. 02L00109).

 

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

Adsorption on soil is not to be expected due to the high solubility of methanol as well as its low octanol-water partition coefficient. Lokke (1984) studied the adsorption of methanol onto three different soil types at 6 deg C. Adsorption coefficients of between 0.13 and 0.61 were measured for all soil types and at all concentrations.

 

QSAR-disclaimer

In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.

According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.

For the assessment of methyl formate (Q)SAR results were used for the estimation of the adsorption potential. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Therefore, further experimental studies on the adsorption potential of methyl formate are not provided.

Overall, based on the measured and estimated data, adsorption of the parent substance along with the hydrolytic products: methanol and formic acid to the solid soil phase is not to be expected.