Potassium nitrate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

range finding: October 5 to 9, 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well performed, limited documented study, according to OECD test guideline and compliant with GLP. However, since the study was performed with a substance analogue and the data are read across, the Klimisch score is 2.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on test solutions:

At test initiation, test solutions were prepared by diluting the appropriate amount of test substance into 15 L of dilution water in the test chamber. Nominal total product test concentrations of 6.25, 12.5, 25.0, 50.0, and 100 mg/L were prepared by diluting approximately 0.0938, 0.1875, 0.3750, 0.7500, and 1.5000 grams of the test substance, respectively. The test substance was stirred into solution with a glass rod. The dilution water control was prepared using only dilution water.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
Common name: Rainbow trout
- Strain: Oncorhynchus mykiss
- Source: obtained as fertilized eggs from Troutlodge, Inc., (Sumner, WA) and were reared for approximately five months prior to definitive test initiation.

ACCLIMATION
- Acclimation period: two-day acclimation period
- Acclimation conditions: Approximately 160 fish were removed from the holding tank and placed in acclimation. Acclimation water temperature ranged from 15.0 to 15.6°C.
- Feeding: fish were not fed during acclimation
- Health during acclimation (any mortality observed): no mortality was observed. No diseases were observed or treated during the holding period prior to test initiation.

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

Total hardness 146 mg/L as CaCO3, total alkalinity 142 mg/L as CaCO3, and conductivity 310 µS/cm.

Test temperature:

14.6 to 15.4°C

pH:

7.56 to 8.12 in control and treatment solutions during the conduct of the definitive test

Dissolved oxygen:

Dissolved oxygen concentrations were equal to or greater than 9.22 mg/L (equal to or greater than 95% of saturation) at initiation of the definitive test. Dissolved oxygen concentrations ranged from 6.16 to 8.14 mg/L (64 to 84% of saturation) during the remainder of the definitive test.

Nominal and measured concentrations:

Nominal total product test concentrations of 6.25, 12.5, 25.0, 50.0, and 100 mg/L were prepared by diluting approximately 0.0938, 0.1875, 0.3750, 0.7500, and 1.5000 grams of the test substance, respectively.

Details on test conditions:

TEST SYSTEM
- Test vessel: 5-gallon glass jars containing 15 L of control or test solution and covered with clear plastic petri dish covers
- Material, size, headspace, fill volume: The glass jars had measurements of
approximately 47 cm (height) by 26 cm (inside-diameter) with 29 cm solution depth
- No. of organisms per vessel: each chamber contained its complement of five fish (or 10 fish
per treatment)
- No. of vessels per concentration (replicates):duplicate
- No. of vessels per control (replicates):duplicate
- No. of vessels per vehicle control (replicates): (one)
- Biomass loading rate: Instantaneous loading was calculated to be 0.35 g of fish tissue per liter of test solution.

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: Fluorescent lighting was maintained on a 16-hour daylight photoperiod with 30-minute simulated dawn and dusk periods.
- Light intensity: The light intensity was measured daily during the definitive test
and ranged from 512 to 526 lux. The light intensity was measured with a LI-COR Model LI-189 light meter equipped with a photometric sensor.

TEST CONCENTRATIONS
- Test concentrations: 0.0 (control), 0.1, 1.0, 10, and 100 mg/L (nominal)
- Results used to determine the conditions for the definitive study: Five fish were tested per treatment. No mortality or sublethal effects were observed in the control or any treatment level following 96-hours of exposure. Based upon the results of this test, nominal total product test concentrations of 6.25, 12.5, 25.0, 50.0, and 100 mg/L were selected for the definitive test.

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: Nominal concentration confirmed by chemical analysis (>80% recovery)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks on result:

other: Nominal concentration confirmed by chemical analysis (>80% recovery)

Details on results:

- Mortality of control: 0%

All toxicity values were determined based on the mean calculated concentrations. No lethal or sublethal effects were noted at the highest concentration tested. Potassium sodium nitrate concentrations were calculated from total nitrate measurements. Measured total ammonium concentrations at the highest concentration tested were < 0.012 and 0.58 mg/L at test initiation and completion, respectively. Measured un-ionized ammonium concentration at the highest concentration tested were < 0.00039 and 0.0062 mg/L, respectively. The measured concentrations of both total and un-ionized ammonia for all control and treatment solutions were included as water quality parameters.

Reported statistics and error estimates:

Statistical analysis of the concentration versus effect data (mortality) was not performed due to the absence of mortality during the definitive test. The slope of the 96-hour dose-response line (log concentration vs. probit) could not be calculated due to the absence of fish mortality.

Validity criteria fulfilled:

yes

Conclusions:

No mortality or sublethal effects.
Nominal 96h-LC50 > 100 mg/L (confirmed by chemical analysis)
NOEC = 100 mg/L

Executive summary:

The acute toxicity of Potassium sodium nitrate to rainbow trout was investigated in a test according to OECD203 and GLP.

Test concentrations were confirmed by chemical analysis (nitrate measurements).

The nominal 96h-LC50 > 100 mg/L and the NOEC is 100 mg/L.

The study was performed with potassium sodium nitrate as a source substance for the target substance (potassium nitrate). The obtained result can be read accross to potassium nitrate.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

fry stage fish were used, which are younger fishes than recommended in OECD 203 - considered as worst case situation

Principles of method if other than guideline:

Fry stage fish were exposed to a series of concentrations of potassium nitrate using aged tap water kept at 25°C. Tests were conducted in 5 gallon aquaria holding 10 or 20 fish, 6-11 mm in length. Water temperature was kept between 25and 27 °C. Mortality and other observations were made at 24, 48, 72 and 96 hours. Oxygen concentration was controlled daily and found to be maintained at 8.30 mg/L during the experiment. Water hardness varied between 117 and 126 mg/L and the pH between 7.40 and 7.68.

GLP compliance:

no

Analytical monitoring:

yes

Details on test solutions:

A stock solution of 2M potassium nitrate was prepared. From this stock solution the aquaria were dosed in five equal and separate batches through a period of 2h to bring the experimental water to the desired final concentration. This was done to avoid a sudden increase in toxicant concentration.
The test concentrations are not given in the publication.

Test organisms (species):

Poecilia reticulata

Details on test organisms:

TEST ORGANISM
- Strain: Poecilia reticulata
- Age at study initiation (mean and range, SD): Fry stage
- Length: 7.8-8.5 mm
- Feeding during test
- Food type: dried commercial food (TetraMin or Biorell) or brine shrimp hatched from eggs obtained from Mateframe Corporation
- Amount: not mentioned
- Frequency: at least once daily, but usually twice daily

ACCLIMATION
- Acclimation period: 48h - same conditions as test period

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

117-126 mg/l CaCO3

Test temperature:

25 - 27 °C

pH:

7.4 - 7.68

Dissolved oxygen:

8.3

Details on test conditions:

TEST SYSTEM
- Test vessel: 5 gallon aquaria
- Material, size, headspace, fill volume: held 141 of water
- Aeration: yes
- Type of flow-through (e.g. peristaltic or proportional diluter):
- No. of organisms per vessel: 10-20

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Columbus tap water

OTHER TEST CONDITIONS
- Adjustment of pH: buffered to bring the phosphate concentration to 10^-3M
- Photoperiod: continuously lighted with fluorescent and incandescent bulbs

EFFECT PARAMETERS MEASURED
- The number of dead fish was observed and recorded several times daily.

TEST CONCENTRATIONS
- Not reported

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1 378 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

At a nitrate concentration of 200 mg/l N, 50% of the fish died in the first 70h. In the next 7 days no further deaths were observed.

Sublethal observations / clinical signs:

LC₅₀= 191 mg N/L (1378 mg KNO₃/L; 845 mg NO₃/L)

Validity criteria fulfilled:

not applicable

Conclusions:

LC50= 191 mg N/L (1378 mg KNO3/L; 845 mg NO3/L)

Executive summary:

In a static study with potassium nitrate performed equivalent to OECD 203, only with fry stage fish (younger fish, considered to be a worst case) were exposed to a series of concentrations of potassium nitrate and nitrate concentrations were measured. Based on the measured concentration of nitrate the LC50 of potassium nitrate was calculated to be 1378 mg/L.

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting 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 followed

Principles of method if other than guideline:

Five gallon jars were placed in a constant temperature bath (20°C). Ten fish were placed in each container and tests were run in duplicate for every concentration. Concentration ranged from 2,100 to 4,200 mg KNO3/L. A control group was maintained with every series of test. The pH for the various concentrations ranged from 7.5 to 8.6.

GLP compliance:

no

Analytical monitoring:

no

Test organisms (species):

Lepomis macrochirus

Test type:

static

Water media type:

not specified

Total exposure duration:

96 h

Hardness:

46 - 49 ppm CaCO3

Test temperature:

19-21 degrees Celsius

pH:

7.5 to 8.6

Dissolved oxygen:

4.8 - 8.3 mg/L

Nominal and measured concentrations:

Nominal concentrations:
2,100 mg/L
2,400 mg/L
2,800 mg/L
3,200 mg/L
3,700 mg/L
4,200 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Five gallon Pyrex jars with No. 12 stoppers, each fitted with an aeration tube
- Aeration: Yes, 160 bubbles per minute
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS
KCl: 0.02 g/L
Na2SiO3: 0.02 g/L
NaHCO3: 0.04 g/L
MgSO4.7H2O: 0.04 g/L
Ca(NO3)2: 0.03 g/L
CaCO3: 0.01 g/L
K2HPO4: 0.002 g/L
Ferric citrate/citric acid: 0.004 g Fe3+/L

OTHER TEST CONDITIONS
- Adjustment of pH:no
- Photoperiod: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- mortality (criteria cessation of gill movement, and lack of response to a mechanical stimulus for a period of 5 minutes)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

ca. 3 000 mg/L

Nominal / measured:

nominal

Basis for effect:

mortality (fish)

Details on results:

- Mortality of control: none
- Survival 96h at 2,100 mg/L = 100/100%
- Survival 96h at 2,400 mg/L = 80/80%
- Survival 96h at 2,800 mg/L = 60/60%
- Survival 96h at 3,200 mg/L = 40/40%
- Survival 96h at 3,700 mg/L = 20/20%
- Survival 96h at 4,200 mg/L = 0/0%

Conclusions:

LC50(96-h) = 3,000 mg KNO3/L (1,839 mg NO3/L)

Reference 4

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

No method mentioned.

GLP compliance:

no

Specific details on test material used for the study:

Test substance was stated to be pure.

Analytical monitoring:

no

Test organisms (species):

Gambusia affinis

Test type:

static

Water media type:

not specified

Total exposure duration:

96 h

Sublethal observations / clinical signs:

24h-LC₅₀421 mg potassium nitrate/L,

48h-LC₅₀224 mg potassium nitrate/L,

96h-LC₅₀162 mg potassium nitrate/L.

-          Nominal concentrations (mg/L): 10, 18, 32, 56,  100, 180, 320, 560 and 1000.

-Mortality: 0/10 (up to 100 mg/L), 6/10 (180 mg/L) and 10/10 (320 mg/L and higher).

-  Other effects: turbidity: 0/96 h 140/<25 mg/L.

-Effect concentration vs. test substance solubility: solubility (based on precipitation) higher than effect concentration.

-Dose related effects: mortality, precipitation

Conclusions:

96h-LC50 was established to be 162 mg potassium nitrate/L.

Description of key information

Based on reliable studies with potassium sodium nitrate and potassium nitrate, the 96h-LC50 is >100 mg/L for fish. The read-across rationale can be found in the document attached in the appropriate target endpoint record.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

100 mg/L

Additional information

In a reliable OECD 203 study in Oncorhynchus mykiss with potassium sodium nitrate, the nominal 96h-LC50 was determined to be >100 mg/L (confirmed by chemical analysis). No lethal or sublethal effects were noted at the highest concentration tested. Potassium sodium nitrate concentrations were calculated from total nitrate measurements. This is confirmed in a study with potassium nitrate, in a static study performed equivalent to OECD 203, only with fry stage fish (younger fish, considered to be a worst case). They were exposed to a series of concentrations of potassium nitrate and nitrate concentrations were measured. Based on the measured concentration of nitrate the 96h-LC50 of potassium nitrate was calculated to be 1378 mg/L.