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Environmental fate & pathways

Henry's Law constant

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Description of key information

From the water surface the substance will not evaporate into the atmosphere. 

Key value for chemical safety assessment

at the temperature of:
20 °C

Additional information

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 DMDC (CAS 6864 -37 -5) (Q)SAR results were used for the estimation of the Henry’s Law constant. 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 Henry’s Law Constant are not provided.

 

Assessment

The Henry's Law Constant (HLC) was estimated according to two different methods.

1) The Henry's Law Constant (HLC) was calculated for the uncharged molecule with the bond estimation method of HENRYWIN v3.20 (EPI Suite v4.11; BASF, 2013) to be 8.11E-04 Pa*m³/mol. The estimate is less accurate since the substance was not within the estimation domain of the model.

2) Based on measured data for vapour pressure (0.08 Pa at 20 °C) and water solubility (2010 mg/L at 20 °C) a HLC was estimated to be 9.5E-03 Pa*m³/mol (HENRYWIN v3.20, EPI Suite v4.11; BASF, 2013). This calculated result was selected as key value. The substance is within the applicability domain of the estimation model.

In summary, the HLC of the charged molecule is expected to be < 1 Pa*m³/mol (pH 7, 25°C). Therefore, the substance will not evaporate from the water surface into the atmosphere.