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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, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Please refer to the QMRF and QPRF files provided under the section attached justification.
Qualifier:
according to guideline
Guideline:
other: REACH guidance on QSAR R.6
Deviations:
no
Principles of method if other than guideline:
Estimates the log octanol-water partition coefficient, log KOW, of chemicals using an atom/fragment contribution method.
GLP compliance:
no
Type of method:
calculation method (fragments)
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SMILES: [Li]Br
Key result
Type:
log Pow
Partition coefficient:
ca. -0.37
Temp.:
25 °C
Remarks on result:
other: The substance is not within the applicability domain of the model.

 

 KOWWIN Program (v1.68) Results:

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

Log Kow(version 1.68 estimate): -0.37

SMILES : [Li]Br

CHEM : Lithium bromide

MOL FOR: Br1 Li1

MOL WT : 86.84

 

WARNING - The entered structure is an INORGANIC Compound. Very few inorganic compounds were included in the training data set for the methodology utilized in this program. Therefore, inorganic compounds are outside the estimation domain.

 

TYPE

 NUM

 LOGKOW FRAGMENT DESCRIPTION

 COEFF

 VALUE

Frag

 1

 -Br [bromine, aliphatic attach]

 0.3997

 0.3997

Factor

 1

 {Na,K,Li} [not oxy attach] **questionable!

-1.0000**

 -1.0000

Const

 

 Equation Constant

 

 0.2290

NOTE

 

 An estimated coefficient (**) used

 

 

Log Kow

-0.3713

 

Conclusions:
Using KOWWIN v1.68 the logPow of lithium bromide was calculated to be -0.37 at 25 °C. The substance is not within the applicability domain of the model. Thus the estimation may be less accurate.
Executive summary:

Lithium bromide is an inorganic salt that quickly dissociates in water forming the lithium and bromide ion. Therefore a laboratory study determining the partition coefficient is technically not feasible. The calculation of the partition coefficient of lithium bromide with EPI Suite v4.11 can be seen as estimation as only a few inorganic compounds were included in the training data set of the program. But taken into account the quick dissociation of lithium bromide in water this EPI Suite estimation can be regarded as adequate enough to be used for the risk assessment.

The log Pow was calculated using KOWWIN v1.68 as part of EPISuite v4.11 from US Environmental Protection Agency.

Using KOWWIN v1.68 the log Kow of the test item was calculated to be -0.37 at 25 °C (EPI Suite).

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to thequery chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

Endpoint:
partition coefficient
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance is inorganic
other:

Description of key information

According to column 2 of REACH Regulation 1907/2006/EC Annex VII section 7.8, the test on partition coefficient n-octanol/water does not need to be conducted as lithium bromide is an inorganic compound. Further, the theoretical, calculated log Pow is very low as expected for an inorganic salt.

Key value for chemical safety assessment

Log Kow (Log Pow):
-0.37
at the temperature of:
25 °C

Additional information

Lithium bromide quickly dissociates in water forming the lithium and bromide ion. Therefore a laboratory study determining the partition coefficient is technically not feasible. The calculation of the partition coefficient of lithium bromide with EPI Suite v4.10 can be seen as estimation as only a few inorganic compounds were included in the training data set of the program. But taken into account the quick dissociation of lithium bromide in water this EPI Suite estimation can be regarded as adequate enough to be used for the risk assessment.

The partition coefficient of lithium bromide was estimated using KOWWIN v1.68 embedded in EPI Suite v4.10 of EPA’s Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC). The program is a screening level tool and estimates the log octanol/water partition coefficient log Pow of chemicals using an atom/fragment contribution method. Lithium bromide has a molecular weight of 86.85 g/mol and therefore fits to the applicability domain of this model. A log Pow of -0.37 was derived for the test item.