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Partition coefficient

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Endpoint:
partition coefficient
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 limited documentation / justification
Remarks:
This is an accepted calculation method supported by a limited amount of additional validation.
Justification for type of information:
See attached QMRF/QPRF
Principles of method if other than guideline:
Method: other (calculated): Estimation by KOWWIN program, USEPA/Syracuse Research, v1.40 (see attached QMRF and QPRF).
GLP compliance:
no
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
-4
Temp.:
20 °C
Remarks on result:
other: For the linear form
Conclusions:
A predicted log Kow of -4 ± 1 was determined for HEBMP-H using a relevant estimation method. The result is considered reliable.
Endpoint:
partition coefficient
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 limited documentation / justification
Remarks:
This is an accepted calculation method supported by a limited amount of additional validation.
Justification for type of information:
See attached QMRF/QPRF
Principles of method if other than guideline:
Method: other (calculated): Estimation by KOWWIN program, USEPA/Syracuse Research, v1.40 (see attached QMRF and QPRF).
GLP compliance:
no
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
-3.4
Temp.:
20 °C
Remarks on result:
other: For the cyclic form
Conclusions:
A predicted log Kow of -3.4 ± 1 was determined for HEBMP-cyclic using a relevant estimation method. The result is considered reliable.

Description of key information

log Kow [HEBMP-H]: -4 (QSAR)


log Kow [HEBMP-H cyclic]: -3.4 (QSAR)


When adjusted to neutral pH range:
log Kow [linear HEBMP-H]: ≤-4


log Kow [EBMP-H cyclic]: ≤-4

Key value for chemical safety assessment

Log Kow (Log Pow):
-4
at the temperature of:
20 °C

Additional information

Predicted log Kow values of -4± 1 and -3.4 ± 1 at 20°C were determined for linear HEBMP-H and cyclic HEBMP-H respectively using an appropriate QSAR estimation method. The results are considered reliable and are selected as key studies.

Similarly, an estimated log Kow of -4 was also determined for linear HEBMP-H in a reliable supporting study. For environmental exposure assessment, it is appropriate to refer to the value under neutral conditions which is log Kow -4 for both constituents. A predicted log Kow value below -4 is reported as -4. The prediction is for the acid form. As the pH is increased to neutral, ionisation of the phosphonate groups occurs, decreasing the log Kow value. Therefore, the estimated log Kow for the unionised form was corrected for ionisation using the equation CORR = 1/1 +10A(pH-pKa) [where A = 1 for acids, -1 for bases; pH = pH-value of the environment; pKa = acid/base dissociation constant.