Leach residues, zinc ore-calcine, zinc cobalt

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

other: read accross of critical study record from specific substance (CdO) driving classification

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Modified algal medium is used (composition is reported)

GLP compliance:

yes (incl. QA statement)

Remarks:

see original report (no reference number)

Test material

Test material information

Constituent 1

Reference substance name:

Cadmium oxide

EC Number:

215-146-2

EC Name:

Cadmium oxide

Cas Number:

1306-19-0

IUPAC Name:

oxocadmium

Details on test material:

purity > 99.5%
mean diameter: 0.5 µm; rel. density: 7.95 – 8.15

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

MONITORING OF TEST SUBSTANCE CONCENTRATION: at O hours and end of the test (72h). by IPAC.

Test solutions

Vehicle:

no

Details on test solutions:

- the three test solutions obtained from the transformation/dissolution test (LISEC) were, after filtration (0.2 µm) used as stock solutions for this test. Test solutions were prepared by appropriate dilution of the stock with the necessary nutrients (from modified OECD 201 medium with omission of EDTA) and modified ISO 6341 to obtain the test concentrations. All test solutions were spiked with 3.25 ml algal suspension. Test solutions were buffered at pH 8 by passing continuously a stream of 0.033% CO2 over the solutions.

Test organisms

Test organisms (species):

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

Details on test organisms:

- Strain/source: Scenedesmus subspicatus (CCAP; strain 278/4) from the Culture Collection of Algae and Protozoa, UK.
- Breeding method: according to OECD guideline.
- Age: not reported.
- Control: yes.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Details on test conditions:

TEST SYSTEM:
- Concentration tested (total Cd): 0, 9.5; 21; 48; 104 and 223 µg Cd/L
- Renewal of test solution: no.
- Exposure vessel type: 250 ml glass flasks covered with a stop.
- Number of replicates, individuals per replicate: three replicates with test substance, three controls containing only algae and medium and one reference test vessel for each test concentration containing algal medium and the test substance.
Vessels are shaken once a day.
- Test temperature: in general: 21 – 25 °C but sometimes outside and varying by more than 2°C
- pH: 7.54 – 9.88 range in one flask per concentration and control.
- Hardness: Hc: 49mg CaCO3/L
- Intensity of irradiation: 6500 lux
Photoperiod: continuous uniform illumination.
Cell density is measured by spectrophotometry (720.0 nm) at 0, 24, 48 and 72 hours. The algal medium with test substance at the different test concentrations were used as a blank.

Results and discussion

Effect concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

18 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

dissolved

Basis for effect:

growth rate

Details on results:

EC50 (0-72h) for growth rate after 72h, is lower (i.e. 79 µg Cd/L, 95% confidence interval: 71-88 µg Cd/L) than the dissolved cadmium concentration measured after transformation/dissolution (185-307 µg Cd/L).
The objective of the study was to determine the effect of the test substance cadmium oxide, transformed/dissolved in buffered (pH 8) modified ISO 6431 medium during 7 days at a loading of 100 mg CdO/L, on the growth of algae.
CONTROL: growth curve conform to guideline: validity criterion was met: cell conc in the control cultures increased with a factor of 79 within 3 days

Reported statistics and error estimates:

the concentration-effect curve fittings and EC50 were based on the model of Bruce and Versteeg (1992). SAS Procedure NLIN was used to fit the model to data

Any other information on results incl. tables

no

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

cell conc in the control cultures increased with a factor of 79 within 3 days

Conclusions:

Tests done according to standard protocol. Good quality and considered useful for setting the reference value for acute aquatic ecotoxicity.

Executive summary:

Tests done according to standard protocol. Good quality and considered useful for setting the reference value for acute aquatic ecotoxicity. Study used for that purpose in the EU risk assessment process on cadmium (ECB 2008). Culture medium, test water conditions well described and relevant the purpose of setting reference value.