Potassium chlorate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

Sodium chlorate (CAS: 7775-09-9)

Adequacy of study:

key study

Study period:

2002-2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study was carried out according to generally valid and internationally accepted testing guidelines and under GLP.

Justification for type of information:

1. HYPOTHESIS FOR THE ANALOGUE APPROACH

This read-across is based on the hypothesis that the common compound ClO3 - is solely responsible for the effects encountered, because the source and the target substances were transformed (by dissociation) into chlorate-ion (ClO3 - ). Exposure to the non-common compounds (sodium or potassium) does not influence the prediction of the property under consideration. The effects of the target substance (potassium chlorate) are predicted to be equal to the effects of the source substance (sodium chlorate) for the property under consideration. Parent substances Transformation Common compound Non-common compound Source ClHO3.Na ClHO3.Na  ClO3- + Na+ ClO3- Na+ Target ClHO3.K ClHO3.K  ClO3- + K+ ClO3- K + Therefore, read-across is possible for these two substances, because the toxicity of the test substance is expected to be related to the chlorate ion and not to the sodium or potassium ion, and both sodium and potassium chlorate were almost totally dissociated in water, producing sodium/potassium cations and chlorate anions.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target and source substances are both mono-constituent substances. The typical concentration and concentration range for the constituents and all identified impurities are reported in table 1 of the justification document for read across (section15)

Table 1: Composition of the target and source substance


3. ANALOGUE APPROACH JUSTIFICATION
For the target substance, the dataset of physico-chemical properties is complete, except for partition coefficient (see data matrix, Table 3). No experimental study was performed to assess the partition coefficient (log Kow) of the target substance. Even if the partition coefficient of the substance can be waived considering the inorganic nature of the substance, the log Kow of the source substance was evaluated in a GLP and reliable experimental test report, based on the estimation of the solubility of the substance in octanol and in water (solubility ratio method) showing a log Kow < -2.9. Considering the chemical structure of potassium chlorate (KClO3) and sodium chlorate (NaClO3) as well as the position of K (potassium) and Na (sodium) in the Mendeleiv table (K is just below Na in the same column), close behaviour is expected for both substances, especially regarding the weak solubility of both substances in n-octanol (< 1 g/L). The water solubility of the target substance (69,9 g/L at 20°C) was measured to be 10 times less than the source substance (717 g/L at 20°C) but is still highly soluble. It is therefore expected that the partition coefficient would be approximately 10 times less that of the source (sodium) salt. For this reason, a log Kow of -2 has been used for the target substance.

4. DATA MATRIX

CORRESPONDING STANDARD INFORMATION REQUIRED

TARGET (potassium chlorate)
Read-across from the source substance
logKow < - 2 at 20°C
Considering that the target substance is 10 times
less soluble in water than the source substance

SOURCE (sodium chlorate)
logKow < -2.9 at 20°C
OECD TG 117/EU A8/ estimation method (solubility
ratio) (key study) 1 (reliable without restriction)

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Principles of method if other than guideline:

An estimate of the maximum solubility of the test item in n-octanol was performed by mixing the test item with different amounts of n-octanol for approximately 1 hour at room temperature away from light. After shaking a visual assessment of solubility was made. The solubility in water of the test item was previously determined (7775-09-9, Water solubility, Groult, 2004, RS-28186 PSE).

GLP compliance:

yes

Type of method:

estimation method (solubility ratio)

Partition coefficient type:

octanol-water

Key result

Type:

log Pow

Partition coefficient:

< -2.9

Temp.:

20 °C

pH:

0

Type:

Pow

Partition coefficient:

< 0.001

Temp.:

20 °C

pH:

0

The solutions of the test item in n-octanol were all saturated. The preliminary test indicated that the test item was weakly soluble in n-octanol
(< 1 g/L).   
Estimation based on the individual solubilities of the test item in n-octanol and water:
Pow = Coctanol / Cwater: < (1/717) this is < 0.001and log Pow < -2.9The HPLC method or shake-flask method were not applicable (log Pow < -2.9) at 20 degrees Celcius.Consequently, the test was considered to be complete.0 = No data on pH.

Conclusions:

Pow < 0.001 and log Pow < -2.9

Reference 2

Endpoint:

partition coefficient

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

sodium chlorate (CAS: 7775-09-9)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
[further information is included as attachment to Iuclid section 13]

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The analogue approach is based on the chemical structure of potassium chlorate (KClO3) and sodium chlorate (NaClO3) and the position of K (potassium) and Na (sodium) in the Mendeleiv table (K is just below Na in the same column) allowing to anticipate a close behaviour for both substances, especially regarding the weak solubility of both substances in n-octanol (< 1 g/L).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Refer to the Test material section of the source and target records.

3. ANALOGUE APPROACH JUSTIFICATION
See attached document in Iuclid section 13

4. DATA MATRIX
See attached document in Iuclid section 13

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Key result

Type:

log Pow

Partition coefficient:

< -2

Temp.:

20 °C

Remarks on result:

other: pH not reported

Executive summary:

This endpoint can be assessed using a dedicated guideline study. The log Kow of Sodium chlorate (CAS 7775 -09 -9) was evaluated in a GLP and reliable experimental test showing a Log Kow <-2.9. The water solubility of potassium chlorate was measured to be 10 times less than for sodium chlorate but is still highly soluble. It is therefore expected that the partition coefficient would be approximately 10 times less than that of the sodium salt. For this reason a log Kow of -2 has been used in the CSR.

Key value for chemical safety assessment

Log Kow (Log Pow):

-2

at the temperature of:

20 °C

Additional information

This endpoint can be assessed using a dedicated guideline study. The log Kow of Sodium chlorate was evaluated in a GLP and reliable experimental test showing a Log Kow <-2.9. The water solubility of potassium chlorate was measured to be 10 times less than for sodium chlorate but is still highly soluble. It is therefore expected that the partition coefficient would be approximately 10 times less than that of the sodium salt. For this reason a log Kow of-2 has been used in the CSR