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Ecotoxicological information

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 (ZnO) driving classification
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Tests performed according to OECD 201 standard test protocol for algae, growth inhibition test . All test parameters carefully documented, and selected for relevancy for EU waters. Actual zinc concentrations in tests measured.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report date:
1994

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
EDTA was not used in the growth medium because it forms stable complexes with metals.
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Reference substance name:
Zinc oxide
EC Number:
215-222-5
EC Name:
Zinc oxide
Cas Number:
1314-13-2
IUPAC Name:
oxozinc
Details on test material:
pro analysi ZnO was used

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
sampling at beginning, after +/- 36 hours and at end of the test

Test solutions

Vehicle:
no
Details on test solutions:
Suspension of 100 mg/l ZnO (after 24 hrs stirring) was filtered over a 0.45 µm filter (Millipore). The filtrate was further diluted with growth medium. the filtrate and dilutions of filtrate were used for testing.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
An unialgal culture of selenastrum capricornutum was obtained from Culture collection of algae and protozoa (CCAP, UK).tests were initiated with the required initial density of 10 to the 4th cells/ml

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no

Test conditions

Hardness:
24mg CaCO3/l
Test temperature:
25+/-1°C
pH:
7.5
Nominal and measured concentrations:
In the test, a control, a filtrate (0.45 µm filter) of a 100 mg ZnO/l dispersion and a series of four dilutions of the filtrate were tested, using a dilution factor of 3.2. If the concentration of the test substance in the filtrate is expressed as 100%, then the following dilutions were tested: 31.25%, 9.76%, 3.05% and 0.95%.

Results and discussion

Effect concentrationsopen allclose all
Duration:
3 d
Dose descriptor:
NOEC
Effect conc.:
24 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
dissolved
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
IC50
Effect conc.:
136 µg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
dissolved
Basis for effect:
growth rate
Details on results:
results expressed as dissolved zinc, measured.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
good quality study considered useful for PNEC derivation in the EU risk assessment (ECB 2008)
Executive summary:

Tests done according to standard protocol. very good quality and considered useful for setting

a) the reference value for acute aquatic ecotoxicity (the study was used for that purpose in the EU risk assessment process on zinc (ECB 2008).

b) the PNEC for the freshwater. (the study was used to that purpose in the EU risk assessment on zinc (ECB 2008).

Culture medium, test water conditions well described and relevant the purpose of classification and risk assessment.

NOEC and LC50 values: see "results"