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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption
Remarks:
adsorption/desorption
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
According to REACH Annex VIII column 2, adsorption/desorption studies can be waived for substances with a low potential for adsorption. MMB has a logKow < 1 and is inherently biodegradable. Hence, adsorption/desorption studies can be waived for this substance. QSAR calculations indiate a log KOC value of  0.52. Therefore MMB is not expected to bind to soils but rather, if released, will partition to the water compartment. Henry's law constant is reported as 0.1 Pa x m3/mol. Distribution of MMB which is emitted to water has been modelled. It is not expected that MMB will end in the soil compartment.
Principles of method if other than guideline:
QSAR EPISUITE KOCWIN v2 (2012)
Type:
Koc
Value:
1.986
Remarks on result:
other: Estimate from MCI (L/kg)
Type:
Koc
Value:
3.331
Remarks on result:
other: estimate from Log Pow (L/kg)
Type:
log Koc
Value:
0.298
Remarks on result:
other: estimated from MCI
Type:
log Koc
Value:
0.523
Remarks on result:
other: estimated from log Pow
Validity criteria fulfilled:
yes
Conclusions:
Estimated Log Koc=0.5226.
Executive summary:

KOCWIN Program (v2.00) Results:

==============================

SMILES : O(C(CCO)(C)C)C

CHEM  : 1-Butanol, 3-methoxy-3-methyl-

MOL FOR: C6 H14 O2

MOL WT : 118.18

--------------------------- KOCWIN v2.00 Results ---------------------------

Koc Estimate from MCI:

First Order Molecular Connectivity Index : 3.621

Corrected Log Koc : 0.2981

Estimated Koc: 1.986 L/kg

 

Koc Estimate from Log Kow:

Corrected Log Koc: 0.5226

 Estimated Koc: 3.331 L/kg

Description of key information

Estimated Log Koc=0.5226.

Key value for chemical safety assessment

Koc at 20 °C:
3.331

Additional information

Lower KOC values correlate to more mobile organic chemicals and therefore MMB is not expected to bind to soils but rather, if released, will partition to the water column.