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Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07/01/1998-08/04/1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

According to the OECD Guideline and it is GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

The algal stock culture was diluted to an initial cell concentration of =10^5 cells/mL (alga suspension) using the preculture medium.
Test solutions (Screening Test): 0.125g/500mL
Test solutions( Main Test): 125mg/500mL

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

- Origin: Sammlung von algenkulturen, pflanzenphysiologisches Institut der Universität Göttingen
The alga were purified from accompanying bacteria during the study and further cultivated under strictly aseptic conditions.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

25±1ºC

pH:

t0: 8.29
t72h: 10.08

Nominal and measured concentrations:

0; 0.125; 0.25; 0.5; 1.0 and 2.0 mg/L

Details on test conditions:

Three days prior to starting the test, a pre-culture was prepared using the algal stock culture.
3 days before start of the main test an algal pre-culture was prepared and inoculated with the algl stock solution. The concentration range was chosen after the results of the screening test.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.28 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Remarks on result:

other: Screening-Test

Details on results:

The inhibition of the growth rates was calculated by extrapolation of the concentration/response curve.

Validity criteria fulfilled:

yes

Conclusions:

The inhibition of the biomass production to 10 and 50% was calculated as 0.28 mg/L and 2.0mg/L, respectively. The inhibition of the growth rate to 10 and 50% was calculated as 2.0 mg/L and >2.0mg/L by extrapolation of the concentration/response curve, respectively, in comparison to the non affected control.

Executive summary:

The chronic toxicity of the substance towards algae was tested according to OECD Guideline 201 and under GLP compliance.

The toxic effect was investigated by determination of the inhibition of the biomass production and the growth rate of the algae after an exposure period of 72 h. The test has been done at the following nominal concentrations: 0; 0.125; 0.25; 0.5; 1.0 and 2.0 mg/L.

Under the conditions being tested a NOEC as well as a 100% inhibition could not be determined. The inhibition of the biomass production to 10 and 50% was calculated as 0.28 mg/L and 2.0mg/L, respectively. The inhibition of the growth rate to 10 and 50% was calculated as 2.0 mg/L and >2.0mg/L by extrapolation of the concentration/response curve, respectively, in comparison to the non affected control. Within the screening-test at 20 mg/L, the inhibition of the biomass production was found to be 99.3% and that of the growth rate was 75.8%.

Description of key information

Based on a study performed according to the OECD 201 guideline and under GLP compliance, the inhibition of the biomass production to 10 and 50% was calculated as 0.28 mg/L and 2.0mg/L, respectively. The inhibition of the growth rate to 10 and 50% was calculated as 2.0 mg/L and >2.0mg/L by extrapolation of the concentration/response curve, respectively, in comparison to the non-affected control.

This study was considered acceptable for that endpoint.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

2 mg/L