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Ecotoxicological information

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:
May - Jun 2000
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: According to OECD guideline under GLP
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Principles of method if other than guideline:
No relevant
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Estren-Cyanhydrin-3-Neopentylketal
- Analytical purity: 91.7%
- Lot/batch No.: 1368

Sampling and analysis

Analytical monitoring:
yes

Test solutions

Vehicle:
no

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h

Results and discussion

Effect concentrationsopen allclose all
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.9 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate

Any other information on results incl. tables

Biomass and growth rate were inhibited (> 1 0%) at concentrations of 0.1 mg/L and higher. A clear concentration related effect was observed.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
ZK 30367 had an inhibitory effect on the growth of Scenedesmus subspicatus. The EbC50, was 0.4 mg/L, the ErC50 was 0.9 mg/L.
Consequently, ZK 30367 was considered to be very toxic to the green algae Scenedesmus
subspicatus, since the EC50 was below 1 mg/L.
Executive summary:

The purpose of this study was to determine the effects of the test compound Estren-Cyanhydrid-3 -Neopentylketal (ZK 30367) on the growth of the green algae Scenedesmus subspicatus. ZK 30367 is an intermediate ofthe synthesis of gestonorone. The study was conducted in agreement with the test guideline OECD no. 201.

The test substance was incubated in an aqueous solution including nutrients with an algae population of Scenedesmus subspicatus for a test duration of approximately 72 hours in an electronically controlled dosing and incubation apparatus. The nutrient solution was made up of mainly nitrate, phosphatesand some trace elements. For the preparation of the test solutions a suspension with a nominal loading of 100 mg/L test substance in water was treated in an ultrasonic bath for approximately 30 minutes and then stirred for 24 hours. This suspension was filtered through a glassfibre filter. The resulting solution served as the highest concentration ("equivalent to saturated solution"), which was a 1: 1.25 dilution by adding nutrient solution and inoculum. It was further diluted 1 :5, 1: 10, 1 :25, 1 :50 and 1: 100 with demineralized water. Additionally, a control solution was prepared with demineralized water without test material. The organic carbon concentration of the stock solution was analyzed with a TOC analyzer at the start of the incubation. The substance concentration was calculated on the basis of the molecular formula. It was 3.4 mg/L. Accordingly, for the highest test concentration (equivalent to "saturated solution") it was 2.7 mg/L. The concentrations of the further test concentrations were extrapolated from the result ofthe TOC-analysis and are shown in the table below. The algae were exposed to each concentration in triplicate. Six vessels were prepared for the control. The algae were incubated under continuous light, controlled temperature and standard conditions. As a parameter for the growth of the algae population, the fluorescence of the algal cells was measured with a fluorescence-photometer. The increase of biomass and the growth rate were calculated on the basis of the fluorescence. The calculated biomass and growth rate of each concentration were compared to those of the controls, and the inhibition was caIculated.