Reaction mass of [[(2-hydroxyethyl)imino]bis(methylene)]bisphosphonic acid and Phosphonic acid, P-[(tetrahydro-2-hydroxy-2-oxido-4H-1,4,2-oxazaphosphorin-4-yl)methyl]-

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

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.

Reference 2

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 K_ow [HEBMP-H]: -4 (QSAR)

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

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

log K_ow [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 K_ow 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 K_ow 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 K_ow -4 for both constituents. A predicted log K_ow 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 K_ow value. Therefore, the estimated log K_ow for the unionised form was corrected for ionisation using the equation CORR = 1/1 +10^A(pH-pKa) [where A = 1 for acids, -1 for bases; pH = pH-value of the environment; pKa = acid/base dissociation constant.