Lead cyanamidate

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: study was preformed according to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Lead cyanamidate

EC Number:

244-073-9

EC Name:

Lead cyanamidate

Cas Number:

20837-86-9

Molecular formula:

CN2.Pb

IUPAC Name:

λ²-lead(2+) (azanidylenemethylidene)azanide

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

As solubility lies below 100 mg/L, a saturated solution was prepared for the test. This was
done by weihging the nominal load, adding the corresponding amount of dilution water and
shaking vigorously for 24 hours. The resulting solution was filtrated through 0.45 µm filters.
From this stock solution, the concentrations to be tested were prepared by diluting with
dilution water.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Specification

Species/Strain Daphnia magna STRAUS Berlin
Sex female
Age between 0 and 24 hours

Animal Husbandry
Daphnia magna is bred in the LAUS GmbH throughout the year. The animals are kept for the use in toxicity tests. They multiply by parthenogenesis, thus being genetically identi-cal. The keeping is performed similar to the method described in EN ISO 6341, following SOP 115 002 01 („Zucht und Hälterung von Daphnia magna STRAUS“), edition 10, adop-ted 04. Nov. 2010.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Test temperature:

20.0 +/- 2 °C deviation within the test +/-1°C

pH:

7.8 +/-0.2

Dissolved oxygen:

8.2 mg/L

Nominal and measured concentrations:

Treatments test item 1.0 / 2.2 / 4.6 / 10 / 22 mg/L
Treatments positive control 0.5 / 0.625 / 1.0 / 1.25 / 1.5 / 2.0 / 2.5 / 3.0 mg/L

Details on test conditions:

Selection of Daphnia
As M4 Medium contains the complex builder EDTA the adult animals are transferred in dilution water about 48 hours before the start of the test. This will be done to avoid un-wanted effects during analytical determination. 16 - 24 hours before the start of the test, the adult animals are separated from the young. 15 - 23 hours later, the adults are caught with the help of a glass tube, and the newborn daphnia, aged between 0 and 23 hours, are sieved from the medium and immediately placed into a 250 mL-beaker containing dilution water. After a settling-in period of 30 minutes, animals which show no apparent damage are used for the test.

Positive Control
The 24-EC50h of potassium dichromate will be determined in a current test. A stock solution containing 250 mg/L in deionised water will be used to prepare the treatments.

Performance of the Study
Using a glass tube (diameter approx. 8 mm), the daphnia are caught and lifted from the beaker. They are put on a small sieve, and the medium surrounding the animals is sucked off using absorbent paper. Immediately after that, the animals are put into the respective test solution.
The test vessels are left to stand for 48 hours. After 24 and 48 hours, the immobilised daphnia are counted. Daphnia are considered immobilised if they perform no movements or are only able to move their antennae when the beaker is gently agitated. Daphnia which are trapped at the surface of the test solution are also considered immobilised.
The pH and the concentration of dissolved oxygen in the test vessels are measured at the beginning and at the end of the test.
The content of the test item in the test vessels is measured at the beginning and at the end of the test. Samples must not be filtrated.

Reference substance (positive control):

yes

Remarks:

K2Cr2O7

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Effect concentrations 3

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Effect concentrations 4

Duration:

48

Dose descriptor:

EC50

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Any other information on results incl. tables

Immobilities

In the control, none of the daphnia died or showed any signs of abnormal behaviour throughout the test

pH and O₂, Temperature

The pH values in the test media and the control ranged from 7.7 to 8.0. The concentration of dissolved oxygen stayed above 8.2 mg/L throughout the test. Temperature range was 19.5 – 21.0 °C.

At the start and at the end of the test, the content of Pb as main component of the test item (80,3 %) was measured via AAS. The test solutions were concentrated up 10 fold before measurement. The measured values were scattered and in a much lower range than expected. Therefore, in an additional experiment, the solubility of Pb was determined in two saturated solutions (nominal concentration 100 mg/L). One solution was prepared in daphnia test medium and the other solution was prepared in demineralised water.

Because of reactions with the anions in the test medium, the measured Pb concentration in test medium was only 0.5 % of the Pb concentration in deionsed water. That means that analytical determination of valid and repeatable test item concentration was not possible. Therefore, the determination of the biological results was based on the nominal concentrations.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The presented data are reliable and adequate.

Executive summary:

The main study was performed using five concentrations ranging from 1 to 22 mg/L nominal concentration. Twenty daphnia were exposed to the test item for 48 hours in a static test system. After 24 and 48 hours, the immobilised daphnia were counted.

Only the highest concentration showed significant toxicity (75% immobilisation after 48 hours). None of the animals were immobilised in the control.

The 24h-EC50_iof potassium dichromate was tested in a current reference test. The value was determined as 1.6 mg/L, lying within the demanded range of 0.6 – 1.7 mg/L.

 

At the start and at the end of the test, the content of Pb as main component of the test item (80.3 %, determined via RFA, X-ray fluorescence) was measured via AAS. The measured Pb concentrations were unexpectedly low and implausible. Therefore, an additional experiment for the determination of solubility in deionised water and in daphnia test medium was performed.

Because of reactions with the anions in the test medium, the measured Pb concentration in test medium was only 0.5 % of the Pb concentration in deionised water. Furthermore, in the study for determination of solubility in water, it was verified that due to the oxidation of the test item during the test in all flasks and high deviation of the measurements in all flasks, a defined solubility of Blei-cyanamid can not be stated.

 

That means that determination of repeatable measured test item concentrations under test conditions was not possible. The determination of the biological results was based on the nominal concentrations.