Potassium carbamoylcarbamate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-01-4 to 2012-10-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Study conducted via OECD 201

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Remarks:

Exceptions to GLP standards: reference substance characterization and water characterizations performed in Feb 2012 were not to GLP standards

Test material

Test material information

1

Reference substance name:

Potassium carbamoylcarbamate

EC Number:

247-728-7

EC Name:

Potassium carbamoylcarbamate

Cas Number:

26479-35-6

Molecular formula:

C2H3KN2O3

IUPAC Name:

potassium N-carbamoylcarbamate

Test material form:

solid: particulate/powder

Remarks:

migrated information: particulates

Details on test material:

- Name of test material (as cited in study report):Potassium Allophonate
- Physical state:powder
- Analytical purity:83.8%

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
N/A

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Cell density measured at 24, 48 and 72 hours (+/- 1 hr) in control and each treatment. Measurement by direct microscopic counting with hemacytometer. Potassium allophonate test concentrations measured at 0, 24, 48 and 72 hours by removal of 10mL from each control and test treatment. From the 10 mL, a 0.500mL aliquot was removed and diluted with 80:20 acetonitrile:water so the final concentration was within the analytical standard range (0.250 to 1.25 ug a.i./L). Potassium allophonate-fortified samples (QC samples) were also prepared at 0, 24, 48 and 72 hours at a concentration of 0.250 and 1.25 mg a.i./L.

Test solutions

Vehicle:

no

Details on test solutions:

Primary standard (0.10-mg a.i./mL) was prepared by dissolving 0.2387 g of potassium allophonate in 250 mL of test medium. Appropriate volumes of primary standard and test medium were prepared for each test substance treatment at a volume of 1,000 mL.

Test organisms

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Source (laboratory, culture collection): University of Texas at Austin, Department of Botany, Culture Collection of Algae
- Age of inoculum (at test initiation): 3 days

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

N/A

Test conditions

Hardness:

N/A

Test temperature:

23.6 - 24.2 C

pH:

72 hr: 7.5 - 8.6
0 hr: adjusted to 7.5 +/- 0.1

Dissolved oxygen:

N/A

Salinity:

N/A

Nominal and measured concentrations:

Nominal Concentrations: 6.3, 13, 25, 50, and 100 mg/L
O hr Measured Concentrations: Geometric Mean Measured Concentrations:

Details on test conditions:

TEST SYSTEM
- Test vessel: 250ml flask
- Fill volume: 100ml
- Renewal rate of test solution (frequency/flow rate): None
- Initial cells density:approximately 5x 10^3 cells/flask
- Mean Control end cells density: 71.3 x 10^4 cells/mL (143 x initial density)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Autoclaved ABC reagent water with addition of appropriate reagent grade salts
- Intervals of water quality measurement: Temp and pH at 0 and 72 hours

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes, to 7.5 +/- 0.1
- Photoperiod: continuous light
- Light intensity and quality: 8,149 - 8,213
- Orbital shaker table: Swirled at 100 rpm continously

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: hemacytometer

TEST CONCENTRATIONS
- Range finding study: 2012-01-13 with concentrations of 0.1, 1.0, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: Change in cell density at 72 hrs was +38, +12, +20, and +11% in 0.1, 1.0, 10 and 100 mg/L respectively

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 27.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 27.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 27.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 27.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: Yield

Details on results:

- Rapid hydrolysis of potassium allophonate led to all measured concentrations < minimal quantification limit (MQL) at 72 hours.
- At 72 hours, mean control algal cell density was 71.3 x10^4 cells/mL, while potassium allophonate concentrations ranged from 72.5x10^4 to 82.9x10^4 cells/mL. Percent inhibition of algal growth at 72 hours ranged from -2% to -16% from the control.
- For mean growth rate, the 72-hour NOEC was >=27.4 mg/L (based on mean measured concentrations), based on a lack of statistically significant reduction in growth rate from time zero in any tested concentration.
- For yield (biomass) inhibition, the 72-hour NOEC was >=27.4 mg/L (based on mean measured concentrations), based on the lack of statistically significant reduction in yield from time zero in any tested concentration.

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

NOEC values were estimated using one-way ANOVA and a one-tailed Dunnett's test (p=0.05). 95% Confidence limits could not be calculated. Parametric analyses were performed on the 72-hour cell density, growth rate, and yield data as well as the 48-72 hour adjacent growth rate data. Non-parametric analyses were performed on the 24- and 48-hour cell density, growth rate, and yield data as well as the 24-48 hr adjacent growth rate data.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In a 72-hour test with the green algae Pseudokirchneriella subcapitata, no effects on growth rate or yield (biomass) inhibition were observed, resulting in 72-hour NOECs >=27.4 mg/L (measured geometric mean) based on both growth rate and yield (biomass) inhibition endpoints.