Potassium chlorate

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

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

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
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 substance were transformed (by dissociation) into chlorate-ion (ClO3-).

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 source

Reason / purpose for cross-reference:

read-across: supporting information

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 863 mg/kg soil dw

Nominal / measured:

nominal

Basis for effect:

mortality

Remarks on result:

other: potassium chlorate

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 750 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

Remarks on result:

other: sodium chlorate

- Nominal concentrations: 0, 7.5, 37.5, 75, 375 and 750 mg
a.i./kg dw
- Effect data:
Weight: For all concentrations the weight of the worms was
approx. 90-95% of the control.
Mortality: No information given on mortality per test
concentration.
- LC50 > 750 mg a.i./kg dw

Executive summary:

No experimental study is available on the target substance to assess the toxicity of the registered substance to soil macroorganisms. Therefore, good quality data for a related source substance have been read-across for this endpoint. 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 dissociate in water, producing sodium/potassium cations and chlorate anions. The Read-Across justification document is provided in section 13 of IUCLID.

In this study, two worm species were tested Eisenia fetida and Lumbricus terrestris L.. For both species 50% effect was not reached. The LC50 for soil dwelling organisms is greater than 750 mg/kg soil dw sodium chlorate. On a molecular weight basis this is 863 mg/kg soil dw potassium chlorate.

Reference 2

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Not all information necessary is given, no results per concentration given, no analytical monitoring and no GLP. Despite these shortcomings, the results can be used.

Principles of method if other than guideline:

Method: other: artificial soil test, laboratory test of the BBA. Resembles OECD Guideline 207

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Eisenia fetida

Study type:

laboratory study

Substrate type:

other: artificial soil test

Limit test:

no

Total exposure duration:

14 d

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 750 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mortality

- Nominal concentrations: 0, 7.5, 37.5, 75, 375 and 750 mg
a.i./kg dw
- Effect data:
Weight: For all concentrations the weight of the worms was
approx. 90-95% of the control.
Mortality: No information given on mortality per test
concentration.
- LC50 > 750 mg a.i./kg dw

Description of key information

The LC50 for soil dwelling organisms is greater than 750 mg/kg soil dw sodium chlorate. On a molecular weight basis this is 863 mg/kg soil dw potassium chlorate.

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

863 mg/kg soil dw

Additional information

No experimental study is available on the target substance to assess the toxicity of potassium chlorate to soil macroorganisms. Therefore, good quality data for a related source substance (sodium chlorate) have been read-across for this endpoint. 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 dissociate in water, producing sodium/potassium cations and chlorate anions. The Read-Across justification document is provided in section 13 of IUCLID.

 

For sodium chlorate the following studies are available:

Two studies were found valid with restrictions. In the study performed by Haque and Ebing (1983) two worm species were tested Eisenia fetida and Lumbricus terrestris L.. For both species 50% effect was not reached. The other study performed by Bouche and Beugnot (1978) was a field study. Two parcels of land (52x36.2 m) were at first exposed to sodium chlorate at a concentration of 200 kg/ha, about two and a half months later a higher concentration of 400 kg/ha was applied. Control parcels were not exposed. One further parcel was simultaneously exposed to chlordane. Six earthworm species were recovered from control treated parcels and the first application did not result in an effect on any of the species found, there was no significant difference found in number and biomass of earthworms per species compared to the control field. An effect was found one week after the second application of 400 kg/ha. The number and biomass of the earthworm populations reduced compared to the control, but within one month complete recovery was shown.

The LC50 for soil dwelling organisms is greater than 750 mg/kg soil dw sodium chlorate. On a molecular weight basis this is 863 mg/kg soil dw potassium chlorate.