Dipotassium hydrogen citrate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline available

Principles of method if other than guideline:

Materials and methods are well-documented in the publication. The study meets generally accepted scientific principles, but was not conducted in compliance with GLP and no analytical monitoring was carried out.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test material was dissolved in water. The stock solution was added to the test chambers to archieve the desired nominal concentrations.

Test organisms (species):

Scenedesmus quadricauda

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

8 d

Test temperature:

27 °C

pH:

7 (pH of the water used for preparing the stock solution and diluting)
Adjustment of pH: not clear, it is stated that the solution of the test is neutralised unless the effect of the pH of the hazardous water pollutant solution to be studies is part of the test.

Details on test conditions:

vessels per concentration (replicates): 3
vessels per control (replicates): 3

Reference substance (positive control):

not specified

Key result

Duration:

8 d

Dose descriptor:

other: Toxicity Threshold

Effect conc.:

640 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks:

inhibition of cell division of the alga

Key result

Duration:

8 d

Dose descriptor:

NOEC

Effect conc.:

425 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks:

inhibition of cell division of the alga

Remarks on result:

other: derived from the toxicity threshold

Key result

Duration:

8 d

Dose descriptor:

LOEC

Effect conc.:

850 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks:

inhibition of cell division of the alga

Remarks on result:

other:

Remarks:

inhibition of cell division of the alga

Details on results:

Values were reported as toxicity threshold.
The inhibition of cell division caused by water ingredients is determined. The concentration of the algal suspension is measured turbidimetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness. The concentration at which the inhibitory action of a pollutant begins is present in that dilution from a series of dilutions of a pollutant having, at the end of the test period, a mean extinction value that is >= 3% below the mean value of the extinction value for non-toxic dilutions of the test cultures.
The mean value of the extinction is calculated for all test cultures that are free from both toxic influence and stimulation of growth except for those having extinction values outside a standard deviation of <3% and also, the mean value of the extinction for those test cultures having the lowest toxic pollutant concentration within the dilution series.

The study reports the result as a toxicity threshold (a value between the NOEC and the LOEC).

In order to derive the NOEC the toxicity threshold value is divided by 1.5, knowing that the spacing factor between exposure levels is 2.

In order to derive the LOEC the toxicity threshold value is multiplied by 1.5.

=> 640/1.5 = 425 mg/L (rounded to two significant figures) = NOEC

=> 640*1.5 = 850 mg/L (rounded to two significant figures) = LOEC

Validity criteria fulfilled:

not specified

Conclusions:

For the algea Scenedesmus quadricauda an 8 day toxicity threshold value of 640 mg/L, a NOEC value of 425 mg/L and a LOEC value of 850 mg/L can be stated.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Potassium citrate salts are known to show a very high solubility in water and dissociate rapidly.
Potassium in known to be non-toxic. The toxicity is determined by the citrate moiety of the substance.
Because of that a read-across to citric acid is suitable for the determination of the toxicity.

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline available

Principles of method if other than guideline:

Materials and methods are well-documented in the publication. The study meets generally accepted scientific principles, but was not conducted in compliance with GLP and no analytical monitoring was carried out.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

The test material was dissolved in water. The stock solution was added to the test chambers to archieve the desired nominal concentrations.

Test organisms (species):

Scenedesmus quadricauda

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

8 d

Test temperature:

27 °C

pH:

7 (pH of the water used for preparing the stock solution and diluting)
Adjustment of pH: not clear, it is stated that the solution of the test is neutralised unless the effect of the pH of the hazardous water pollutant solution to be studies is part of the test.

Details on test conditions:

vessels per concentration (replicates): 3
vessels per control (replicates): 3

Reference substance (positive control):

not specified

Key result

Duration:

8 d

Dose descriptor:

other: Toxicity Threshold

Effect conc.:

640 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks:

inhibition of cell division of the alga

Key result

Duration:

8 d

Dose descriptor:

NOEC

Effect conc.:

425 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks:

inhibition of cell division of the alga

Remarks on result:

other: derived from the toxicity threshold

Key result

Duration:

8 d

Dose descriptor:

LOEC

Effect conc.:

850 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Remarks:

inhibition of cell division of the alga

Remarks on result:

other:

Remarks:

inhibition of cell division of the alga

Details on results:

Values were reported as toxicity threshold.
The inhibition of cell division caused by water ingredients is determined. The concentration of the algal suspension is measured turbidimetrically (while diffused light is screened off) and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness. The concentration at which the inhibitory action of a pollutant begins is present in that dilution from a series of dilutions of a pollutant having, at the end of the test period, a mean extinction value that is >= 3% below the mean value of the extinction value for non-toxic dilutions of the test cultures.
The mean value of the extinction is calculated for all test cultures that are free from both toxic influence and stimulation of growth except for those having extinction values outside a standard deviation of <3% and also, the mean value of the extinction for those test cultures having the lowest toxic pollutant concentration within the dilution series.

The study reports the result as a toxicity threshold (a value between the NOEC and the LOEC).

In order to derive the NOEC the toxicity threshold value is divided by 1.5, knowing that the spacing factor between exposure levels is 2.

In order to derive the LOEC the toxicity threshold value is multiplied by 1.5.

=> 640/1.5 = 425 mg/L (rounded to two significant figures) = NOEC

=> 640*1.5 = 850 mg/L (rounded to two significant figures) = LOEC

Validity criteria fulfilled:

not specified

Conclusions:

For the algea Scenedesmus quadricauda an 8 day toxicity threshold value of 640 mg/L, a NOEC value of 425 mg/L and a LOEC value of 850 mg/L can be stated.

Description of key information

For the algea Scenedesmus quadricauda an 8 day toxicity threshold value of 640 mg/L, a NOEC value of 425 mg/L and a LOEC value of 850 mg/L can be stated.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

425 mg/L