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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
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 adequate and reliable documentation / justification
Justification for type of information:
QSAR prediction: US EPA accepted QSAR method for chemicals properties assessment.
Qualifier:
according to
Guideline:
other: QSAR model
Principles of method if other than guideline:
EPI Suite v 4.0/ECOSARv1.00
GLP compliance:
no
Remarks:
not applicable. QSAR model
Analytical monitoring:
not required
Vehicle:
no
Test organisms (species):
other: Daphnid species
Test type:
other: QSAR model
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
not applicable. QSAR model
Test temperature:
not applicable. QSAR model
pH:
not applicable. QSAR model
Dissolved oxygen:
not applicable. QSAR model
Salinity:
not applicable. QSAR model
Nominal and measured concentrations:
not applicable. QSAR model
Details on test conditions:
-Name of test material (as cited in study report:Potassium oxide
CAS Number: 12136-45-7
SMILES : KOK
CHEM : Potash (potassium oxide)
MOL FOR: O1 K2
MOL WT : 94.20
Values used to Generate ECOSAR Profile

Log Kow: -1.380 (EPISuite Kowwin v1.68 Estimate)
Wat Sol: 1E+006 (mg/L, EPISuite WSKowwin v1.43 Estimate)


Reference substance (positive control):
not required
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
6 675.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
The ECOSAR QSAR model predicts that LC50 for fresh water species Daphnid would to be 6675.5mg/l therefore that the substance is non toxic to Daphnid.

Overview of QSARs estimations on short-term aquatic toxicity of Dipotassium oxide/Potassium oxide -to Daphnid     

 

Method

 

Results

Remarks

Reference

QSAR

estimate

Daphnid , 48-hr LC50 =6675.5 mg/L (ppm)

 

Daphnid, 30-day, ChV (chronic value) = 273.134 mg/L (ppm)

 

 

Reliable with restrictions,

QSAR estimated data

ECOSAR Program (v1.00)

 

Using the EPIWIN ECOSAR QSAR model aLC50 for fresh water Daphnid of 6675.5 mg/l was established.

 

Daphnid , 48-hr LC50 =6675.5 mg/L (ppm)

Daphnid, 30-day, ChV (chronic value) = 273.134 mg/L (ppm)

 

Validity criteria fulfilled:
yes
Remarks:
US EPA accepted QSAR method for chemicals properties assessment.
Conclusions:
The ECOSAR QSAR model predicts that LC50 for fresh water species Daphnid would to be 6675.5 mg/l therefore that the substance is non toxic to Daphnid.
Executive summary:

The ECOSAR QSAR model predicts that LC50 for fresh water species Daphnid would to be 6675.5 mg/l therefore that the substance is non toxic to Daphnid.

 Daphnid , 48-hr LC50 = 6675.5mg/L (ppm)

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
other: Published data
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Principles of method if other than guideline:
- Toxicity tests followed the general guidance of the U.S. Environmental Protection Agency (USEPA) for conducting acute whole effluent toxicity tests:
U.S. Environmental Protection Agency. 1991. Methods for measuring the acute toxicity of effluents to freshwater and marine organisms, 4th ed. EPA/600/4-90/027. Cincinnati, OH.
and
U.S. Environmental Protection Agency. 1991. Methods for aquatic toxicity identification evaluations. Phase I toxicity characterization procedures, 2nd ed. EPA/600/6-91/003. Washington, DC.
- Test methods are equivalent or similar to OECD 202
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Dissolved oxygen (DO) and pH were measured in selected test solutions during actual toxicity testing, primarily on solutions near the threshold for acute toxicity.
Vehicle:
not specified
Details on test solutions:
Test solutions were prepared by dissolving individual ion salts in moderately hard reconstituted water.
Test organisms (species):
Daphnia magna
Details on test organisms:
- Two species of daphnids were tested: Daphnia magna and Ceriodaphnia dubia.
- All organisms used in testing were obtained from in-house cultures (ENSR, Fort Collins, CO, USA). Daphnids were less than 24 h old at test initiation. D. magna were cultured in hard reconstituted at 20 °C water and C. dubia were cultured in either moderately hard reconstituted water (MHRW) or 20% mineral water at 25 °C. Reference:
U.S. Environmental Protection Agency. 1991. Methods for measuring the acute toxicity of effluents to freshwater and marine organisms, 4th ed. EPA/600/4-90/027. Cincinnati, OH.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
no data
Test temperature:
D. magna: 20 °C
pH:
Measured pH varied according to the components of the solution (several inorganic salts were tested in this study) but was generally between pH 7.5 and 9.0.
Dissolved oxygen:
Measured DO concentrations were always within an acceptable range (> 40% saturation).
Reference: U.S. Environmental Protection Agency. 1991. Methods for measuring the acute toxicity of effluents to freshwater and marine organisms, 4th ed. EPA/600/4-90/027. Cincinnati, OH.
Salinity:
no data
Nominal and measured concentrations:
Test solution of potassium chloride was prepared by serially diluting a 10,000-mg/L stock solutions with MHRW to develop a series of test concentrations spaced on a 0.5 x dilution factor (i.e., 10,000, 5,000, 2,500, 1,250 mg/L). As testing proceeded and effect thresholds were determined, test concentrations were often spaced much more closely (e.g., 2,500, 2,000, 1,500, 1,000, 500 mg/L) to better define responses near the effect threshold.
Details on test conditions:
All tests were conducted in 30-ml plastic beakers containing 10 ml of test solution and five organisms per chamber.
Reference substance (positive control):
yes
Remarks:
Sodium chloride (NaCl)
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
>= 580 - <= 880 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: D. magna
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
>= 480 - <= 880 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: D. magna
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
660 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: D. magna: arithmetic mean after 48 h exposure is given as 660 mg/L
Details on results:
Effect range for D. magna is given from n=3 tests.
D. magna: arithmetic mean after 48 h exposure is given as 660 mg/L
Results with reference substance (positive control):
48-h LC50 values for NaCl averaged 1,042 mg/L:
To determine whether the results of reference toxicant tests related to the responses observed in the concurrent exposures to ion combinations, LC50 values were calculated for the reference toxicant tests from the first 11 test groups with C. dubia (total of 1,045 ion solutions tested). During this period, 48-h LC50 values for NaCl averaged 1,042 mg/L as Cl2 with a coefficient of variation equal to 24%. The LC50 value from the concurrent reference toxicant test was included as an independent variable for each ion solution and thus considered by the stepwise logistic regression. In this analysis, the reference reference toxicant variable was not selected as being statistically significant, explaining only 0.12% of the overall variance.
From this, we surmised that there was no consistent relationship between the sensitivity of the test organisms (as measured by the reference toxicant test) and the responses of organisms in the concurrent ion exposures. For this reason, the reference toxicant test results were not considered further in subsequent regressions.

- Ion concentrations in the stock solution differed less than 20% from nominal concentrations (exact values not given) and, thus, nominal concentrations were used to give the result.

- Several inorganic salts were tested in this study and the following is given but does not detail if this information is relevant for potassium chloride:

In some analyses, the measured concentrations of cations and anions (expressed as milliequivalents or meq) in a salt solution were not similar. Because charge balance is a physical/chemical requirement, such solutions were further evaluated to determine which concentration (cation or anion) was closer to the nominal value. In all cases, the cation concentration was closer to the nominal value; based on this, the anion concentration in the stock solution was changed to the concentration (in meq) of the corresponding cation.

- To calculate ion concentrations in actual test solutions, the concentrations in the applicable stock solutions were multiplied by the relative proportion of each solution in the test solution. Because the dilution water (MHRW) also contained small concentrations of each ion, these background concentrations were then added to the calculated contributions from the stock solutions.

Validity criteria fulfilled:
not applicable
Remarks:
No data on control immobility; dissolved oxygen concentration was > 40 % which would fulfill the criteria
Conclusions:
The study was conducted according to U.S. national methods. However, the criteria were in most parts equivalent to REACH guidance and OECD guideline. Thus, the study can be evaluated as reliable and in accordance with REACH requirements.
Executive summary:

Short-term toxicity to aquatic invertebrates was determined with standard test species Daphnia magna according to U.S. EPA methods which are equivalent or similar to OECD method 202 and is given as 48 hour-EC50 = 660 mg/L (D. magna)

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
other: Published data
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Principles of method if other than guideline:
- Toxicity tests followed the general guidance of the U.S. Environmental Protection Agency (USEPA) for conducting acute whole effluent toxicity tests:
U.S. Environmental Protection Agency. 1991. Methods for measuring the acute toxicity of effluents to freshwater and marine organisms, 4th ed. EPA/600/4-90/027. Cincinnati, OH.
and
U.S. Environmental Protection Agency. 1991. Methods for aquatic toxicity identification evaluations. Phase I toxicity characterization procedures, 2nd ed. EPA/600/6-91/003. Washington, DC.
- Test methods are equivalent or similar to OECD 202
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Dissolved oxygen (DO) and pH were measured in selected test solutions during actual toxicity testing, primarily on solutions near the threshold for acute toxicity.
Vehicle:
not specified
Details on test solutions:
Test solutions were prepared by dissolving individual ion salts in moderately hard reconstituted water.
Test organisms (species):
Ceriodaphnia dubia
Details on test organisms:
- Two species of daphnids were tested: Daphnia magna and Ceriodaphnia dubia.
- All organisms used in testing were obtained from in-house cultures (ENSR, Fort Collins, CO, USA). Daphnids were less than 24 h old at test initiation. D. magna were cultured in hard reconstituted at 20 °C water and C. dubia were cultured in either moderately hard reconstituted water (MHRW) or 20% mineral water at 25 °C. Reference:
U.S. Environmental Protection Agency. 1991. Methods for measuring the acute toxicity of effluents to freshwater and marine organisms, 4th ed. EPA/600/4-90/027. Cincinnati, OH.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
not applicable
Hardness:
no data
Test temperature:
C. dubia: 25 °C
pH:
Measured pH varied according to the components of the solution (several inorganic salts were tested in this study) but was generally between pH 7.5 and 9.0.
Dissolved oxygen:
Measured DO concentrations were always within an acceptable range (> 40% saturation).
Reference: U.S. Environmental Protection Agency. 1991. Methods for measuring the acute toxicity of effluents to freshwater and marine organisms, 4th ed. EPA/600/4-90/027. Cincinnati, OH.
Salinity:
no data
Nominal and measured concentrations:
Test solution of potassium chloride was prepared by serially diluting a 10,000-mg/L stock solutions with MHRW to develop a series of test concentrations spaced on a 0.5 x dilution factor (i.e., 10,000, 5,000, 2,500, 1,250 mg/L). As testing proceeded and effect thresholds were determined, test concentrations were often spaced much more closely (e.g., 2,500, 2,000, 1,500, 1,000, 500 mg/L) to better define responses near the effect threshold.
Details on test conditions:
All tests were conducted in 30-ml plastic beakers containing 10 ml of test solution and five organisms per chamber.
Reference substance (positive control):
yes
Remarks:
Sodium chloride (NaCl)
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
>= 580 - <= 630 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: C. dubia
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
>= 580 - 670 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: C. dubia
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
630 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: immobility
Remarks on result:
other: C. dubia: arithmetic mean after 48 h exposure is given as 630 mg/L
Details on results:
Effect range for C. dubia is given from n=3 tests.
C. dubia: arithmetic mean after 48 h exposure is given as 630 mg/L
Results with reference substance (positive control):
48-h LC50 values for NaCl averaged 1,042 mg/L:
To determine whether the results of reference toxicant tests related to the responses observed in the concurrent exposures to ion combinations, LC50 values were calculated for the reference toxicant tests from the first 11 test groups with C. dubia (total of 1,045 ion solutions tested). During this period, 48-h LC50 values for NaCl averaged 1,042 mg/L as Cl2 with a coefficient of variation equal to 24%. The LC50 value from the concurrent reference toxicant test was included as an independent variable for each ion solution and thus considered by the stepwise logistic regression. In this analysis, the reference reference toxicant variable was not selected as being statistically significant, explaining only 0.12% of the overall variance.
From this, we surmised that there was no consistent relationship between the sensitivity of the test organisms (as measured by the reference toxicant test) and the responses of organisms in the concurrent ion exposures. For this reason, the reference toxicant test results were not considered further in subsequent regressions.

- Ion concentrations in the stock solution differed less than 20% from nominal concentrations (exact values not given) and, thus, nominal concentrations were used to give the result.

- Several inorganic salts were tested in this study and the following is given but does not detail if this information is relevant for potassium chloride:

In some analyses, the measured concentrations of cations and anions (expressed as milliequivalents or meq) in a salt solution were not similar. Because charge balance is a physical/chemical requirement, such solutions were further evaluated to determine which concentration (cation or anion) was closer to the nominal value. In all cases, the cation concentration was closer to the nominal value; based on this, the anion concentration in the stock solution was changed to the concentration (in meq) of the corresponding cation.

- To calculate ion concentrations in actual test solutions, the concentrations in the applicable stock solutions were multiplied by the relative proportion of each solution in the test solution. Because the dilution water (MHRW) also contained small concentrations of each ion, these background concentrations were then added to the calculated contributions from the stock solutions.

Validity criteria fulfilled:
not applicable
Remarks:
No data on control immobility; dissolved oxygen concentration was > 40 % which would fulfill the criteria
Conclusions:
The study was conducted according to U.S. national methods. However, the criteria were in most parts equivalent to REACH guidance and OECD guideline. Thus, the study can be evaluated as reliable and in accordance with REACH requirements.
Executive summary:

Short-term toxicity to aquatic invertebrates was determined with non-standard test species Ceriodaphnia dubia according to U.S. EPA methods which are equivalent or similar to OECD method 202 and is given as 48 h-EC50 = 630 mg/L

Description of key information

Short-term toxicity to aquatic invertebrates was determined with standard test species Daphnia magna according to U.S. EPA methods which are equivalent or similar to OECD method 202 and is given as 48 hour-EC50 = 660 mg/L (D. magna) 
The available data for saltwater invertebrates are limited and to obtaine the value for PNECs for saltwaters is taken account a assesment factor 10 to extrapolate to LC50/EC50 following the “Guidance on Information Requirement and Chemical Safety Assessment R.10: Characterisation of dose [concentration]- response for environment”and “Table R.10-5 Assessment factors proposed for deriving PNEC water for saltwater for different data sets”, to account for the possibility that greater taxonomic diversity in the marine environment makes it likely that some marine taxa may be more sensitive than the most sensitive freshwater taxa

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
660 mg/L
EC50/LC50 for marine water invertebrates:
66 mg/L

Additional information

Short-term toxicity to aquatic invertebrates was determined with standard test species Daphnia magna according to U.S. EPA methods which are equivalent or similar to OECD method 202 and is given as 48 hour-EC50 = 660 mg/L (D. magna)

The available data for saltwater invertebrates are limited and to obtaine the value for PNECs for saltwaters is taken account a assesment factor 10 to extrapolate to LC50/EC50 following the “Guidance on Information Requirement and Chemical Safety Assessment R.10: Characterisation of dose [concentration]- response for environment”and “Table R.10-5 Assessment factors proposed for deriving PNEC water for saltwater for different data sets”, to account for the possibility that greater taxonomic diversity in the marine environment makes it likely that some marine taxa may be more sensitive than the most sensitive freshwater taxa