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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
09/01/19
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
Remarks:
Calculation of bioconcentration factors to determine the log Koc of chemicals is acceptable provided that a recognised and scientifically robust method is used. This approach is considered to be acceptable with restrictions.
Justification for type of information:
Calculation of bioconcentration factors to determine the log Koc of chemicals is acceptable provided that a recognised and scientifically robust method is used. This approach is considered to be acceptable with restrictions.
Principles of method if other than guideline:
log Koc was calculated using the US EPA Episuite V4.11 program using a Log Kow of 3.42.
GLP compliance:
no
Type of method:
other: QSAR
Key result
Sample No.:
#1
Type:
log Koc
Value:
2.968 dimensionless
Remarks on result:
other: Based on QSAR therefore paramters not valid
Validity criteria fulfilled:
not applicable
Conclusions:
The log Koc for 2,3-dimethylbutane is calculated to be 2.968.
Executive summary:

The log Koc for 2,2-dimethylbutane is calculated to be 2.968. The bioconcentration potential of 2,3-dimethylbutane was estimated using the Episuite program v 4.11 provided by the US EPA. This QSAR model is well documented and peer reviewed. The input parameters included: CAS Number: 79 -29 -8 and a log Kow of 3.42.

Description of key information

The log Koc for 2,3-dimethylbutane is calculated to be 2.968.

As the log Kow of 2,3 -dimethylbuitane is >3, the adsorption/desorption endpoint cannot be waived. However, ECHA's Guidance on Information Requirements and Chemical Safety Assessment R7a Endpoint Specific Guidance (2008) indicates that before commissioning a new study alternative sources of data (e.g. QSAR) on the adsorption/desorption potential of a chemical should be used. The log Koc of n-hexane was calculated to be 3.34. This has been read across to 2,3 -dimethylbutane.

Key value for chemical safety assessment

Koc at 20 °C:
928.6

Additional information

[LogKoc: 2.97]