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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to the solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

Parent compound methyl chloroformate

In order to assess the adsorption potential of the parent compound methyl chloroformate (CAS 79-22-1), the Koc value was estimated using QSAR models (BASF SE, 2019). According to the MCI method of the KOCWIN v2.00 module of EPI Suite v4.11 the substance has a Koc of 1.51 L/kg (log Koc = 0.18). 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 (estimated log Kow = 0.14; KOWWIN v1.68, BASF SE, 2019). The latter method resulted in a Koc of 5.93 L/kg (log Koc = 0.77); 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, the parent compound methyl chloroformate (CAS 79-22-1) rapidly hydrolyses in contact with water and forms methanol (CAS 67-56-1). The adsorption potential will, therefore, be also assessed based on information available for the hydrolysis product methanol.

 

Hydrolysis product methanol:

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.

In support, the adsorption potential of methanol (CAS 67-56-1) was estimated for molecule using KOCWIN v2.00 (BASF SE, 2019). According to the MCI method of the KOCWIN v2.00 module the substance has a Koc of 1.223 L/kg (log Koc = 0.087). 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 (estimated log Kow = -0.77; measured, Lokke, 1984). The latter method resulted in a Koc of 1.22 L/kg (log Koc = 0.09); the substance is within the applicability domain of both estimation models. 

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

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 chloroformate (CAS 79-22-1 (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 are not provided.