Potassium cyanate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-07-11-2013-10-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

02 October 2012

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.20 (Daphnia magna Reproduction Test)

Version / remarks:

30 May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1300 (Daphnid Chronic Toxicity Test)

Version / remarks:

April 1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: The following concentrations (based on Potassium cyanate, KOCN) were prepared on each analytical occasion: 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.0 mg/L, 2.5 mg/L, 5.0 mg/L and 10 mg/L.
- Sampling method: UV/VIS-analysis of the test concentration of 15 mg/L was performed after dilution of the sample (factor 2) in Daphnia medium to meet the linear range of the calibration line.
- Sample storage conditions before analysis: Samples (standards and test concentrations) were buffered to pH 4.5 with buffer solution (ammonium acetate/acetic acid) and 5 mL of each sample were pipetted into a cylindrical glass tube. 1 mL of a freshly prepared solution of anthranilic acid in deionised water (ca. 30 mM) was added, the tubes were stoppered and thoroughly shaken. The tubes were then thermostated for 60 min at 25 °C in a water bath. In the following reaction step 1 was stopped by transferring the samples into an ice bath. To achieve the formulation of benzoylene urea (reaction step 2), 6.2 mL of 37 % hydrochloric acid (12 N) were added to each tube, leading to a final concentration of > 6 mol/L of hydrochloric acid. The tubes were then shaken and transferred into a thermo reactor (100 °C) for ten minutes.

Vehicle:

no

Details on test solutions:

- Controls: Were kept in culturing medium
- Chemical name of vehicle: No solvent was used.
- Concentration of test medium: Test solutions were prepared from stock solutions of 1.0 g/L of the test item in culturing medium by mechanical dispersion.

Test organisms (species):

Daphnia magna

Details on test organisms:

- Common name: Daphnia magna (Crustacea, Daphniidae)
- Strain/clone: Crustacea, Daphniidae, Clone 5
- Source: German Environmental Ministry, Berlin
- Feeding during test: Yes
- Food type: The animals were fed with algae (Desmodesmus subspicatus)
- Acclimation conditions: The animals were cultivated in an air-conditioned room, during the pre-treatment.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

None

Hardness:

>=255/L

Test temperature:

Range Finding Test: 19.6 - 20.1 °C
Definitive Test: 21.2 - 22.7 °C

pH:

Test solutions: 6 - 9

Dissolved oxygen:

above 3 mg/L

Salinity:

NA

Nominal and measured concentrations:

Nominal concentrations: 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.0 mg/L, 2.5 mg/L, 5.0 mg/L and 10 mg/L
Measured concentrations: Analysis of the test solutions for potassiun cyanate confirmed that the test solutions were correctly dosed and stable during the exposure period (recoveries from 90.1 to 107 %). Therefore, the concentrations were reported as nominal concentrations.

Details on test conditions:

- Duration: 96 h
- Aeration: None
- Renewal rate of test solution (frequency/flow rate): 48 h
- No. of organisms per vessel: 10 animals/test concentration and control
- No. of vessels per concentration (replicates): 2 replicates with 5 daphnia
- Test-Medium: According to OECD Guideline
- Light intensity: 1100 Lux

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

0.5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

2.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

0.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

- Mortality of parent animals: The test item Potassium cyanate caused no mortality at nominal test concentrations of 0.10 to 1.2 mg/L. Mortality of the parent daphnia was 10 % at 2.8 mg Potassium cyanate/L, 30 % at 6.5 mg/L and 100 % at 15.0 mg/L.
- No. of offspring produced per day per female: Dead offspring and aborted eggs were observed occasionally during the test in the control (11 dead juveniles / 12 aborted eggs), at test concentration of 0.10 mg/L (9 dead juveniles / 11 aborted eggs), at test concentration of 0.5 mg/L (14 dead juveniles / 9 aborted eggs), at test concentration of 1.2 mg/L (15 dead juveniles / 10 aborted eggs) and at test concentration of 2.8 mg/L (19 dead juveniles / 10 aborted eggs). The number of dead offspring was increased at test concentration of 6.5 mg/L (28 dead juveniles /4 aborted eggs).
- Type and number of behavioural abnormalities: At test concentration of 6.5 mg/L activity of four of the surviving animals of the Parental generation (P) was slightly reduced compared to the control and activity of another animal of the Parental generation (P) was strongly reduced compared to the control at the end of the test. As a tendency these Daphnia were found in the lower parts of the test vessels. Three animals of the Parental generation (P) showed discolouration at the end of the test. At test concentration of 15.0 mg/L growth, development and activity of the animals of the Parental generation (P) were strongly affected. Reproduction did not occur and all Daphnia died during 19 days. All animals of the Parental generation (P) showed discolouration and this finding could be observed from day 7 until day 19 of the test. UV/VIS-analysis confirmed that the test solutions were correctly dosed and that the test concentrations were stable throughout the exposure period. As a consequence the results of the Definitive Test were based on nominal concentrations. The mortality of the parent animals didn't exceed 20 % at the end of the test. The mean number of live offspring produced per parent in the control animals surviving at the end of the test was >=60.

Results with reference substance (positive control):

- Results with reference substance valid? YES

Validity criteria fulfilled:

yes

Conclusions:

The following results for the Repoduction Test with Daphnia magna to Potassium cyanate were determined:
NOEC: 0.1 mg/L
LOEC: 0.5 mg/L
EC50: 2.9 mg/L
EC10: 0.2 mg/L

Executive summary:

The aim of the study was to evaluate the influence of Potassium cyanate on the reproduction output of Daphnia magna in a semi-static test system. The study is based on the procedures indicated in the OECD Guideline 211 (October 2012), in the Commission Regulation (EC) No 440/2008 C.20 (May 2008) and the EPA Guideline OPPTS 850.1300 (April 1996). Young female Daphnia aged less than 24 hours at the start of the test were exposed to aqueous test media containing the test item for 21 days at a range of concentrations. The nominal concentrations were 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.0 mg/L, 2.5 mg/L, 5.0 mg/L and 10 mg/L. Analytical determinations showed that the test item concentrations remained in the range of +/- 20%. In conclusion to this the results are based on nominal item concentrations. The reproduction of the parent animals was statistically significant different from that of the F1 generation. The NOEC was 0.1 mg/L and the LOEC was 0.5 mg/L. The EC50 of the test item was calculated to be 0.81 mg/L, EC10 was calculated to be 0.2 mg/L. The mortality of the parent animals didn´t exceed 20 % at the end of the test. The mean number of live offspring produced per parent in the control animals surviving at the end of the test was >=60.

Description of key information

The long term toxicity to aquatic invertebrates was assessed according to OECD guideline 211, EU method C.20 and OPPTS 850.1300. Daphnids were exposed to the test item under semi-static conditions for 21 days. The nominal concentrations were 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.0 mg/L, 2.5 mg/L, 5.0 mg/L and 10 mg/L. The NOEC was 0.1 mg/L and the LOEC was 0.5 mg/L. The EC50 of the test item was calculated to be 0.81 mg/L, EC10 was calculated to be 0.2 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC10

Effect concentration:

0.2 mg/L

Additional information

The aim of the study was to evaluate the influence of Potassium cyanate on the reproduction output of Daphnia magna in a semi-static test system. The study is based on the procedures indicated in the OECD Guideline 211 (October 2012), in the Commission Regulation (EC) No 440/2008 C.20 (May 2008) and the EPA Guideline OPPTS 850.1300 (April 1996). Young female Daphnia aged less than 24 hours at the start of the test were exposed to aqueous test media containing the test item for 21 days at a range of concentrations. The nominal concentrations were 0.10 mg/L, 0.25 mg/L, 0.50 mg/L, 1.0 mg/L, 2.5 mg/L, 5.0 mg/L and 10 mg/L. Analytical determinations showed that the test item concentrations remained in the range of +/- 20%. In conclusion to this the results are based on nominal item concentrations. The reproduction of the parent animals was statistically significant different from that of the F1 generation. The NOEC was 0.1 mg/L and the LOEC was 0.5 mg/L. The EC50 of the test item was calculated to be 0.81 mg/L, EC10 was calculated to be 0.2 mg/L. The mortality of the parent animals didn´t exceed 20 % at the end of the test. The mean number of live offspring produced per parent in the control animals surviving at the end of the test was >=60.