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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
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report Date:
2015

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder

Test solutions

Vehicle:
yes
Details on test solutions:
The water with conductivity smaller than 5 μS·cm-1 was used for the preparation of solutions. All chemicals used were of analytical-grade.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
The green freshwater algae Desmodesmus subspicatus Brinkmann 1953/SAG 86.81 obtained from the collection of autotrophic organisms of The Botanic Institute of the Czech Academy of Science, Třeboň on date 3.6.2014.
The sensitivity of test species is periodically monitored by testing with the reference substance, potassium dichromate. The strain culture was preinoculated from the stock solution and cultivated in flasks with the test medium on indirect daylight at laboratory temperature. Algae inoculum for the test was sampled from exponentially growing inoculum culture. The strain culture was always set to pre-culturing of cells for 3-4 days before the start of the test. Inoculum culture was kept 3-4 days under conditions at which the test was performed. After this period the culture was in the state of the exponential growth and had the cell density suitable for the performance of the test. The cell density of the pre-culture was measured just before the start of the test and the needed inoculum volume was calculated

Study design

Test type:
not specified
Water media type:
not specified
Limit test:
no
Total exposure duration:
72 h

Test conditions

Test temperature:
22.5°C
pH:
7.6
Details on test conditions:
Temperature: 21 - 24 °C controlled at ± 2 °C
Lighting: under continuous white light, 4 440 lux to 8 880 lux
Exposition time: 72 hours
Volume of tested mixture: 50 mL
Initial concentration of algae culture: 5 000 cells in a 1 mL
Without aeration.
Agitation of algae culture by shaking.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.53 mg/L
Nominal / measured:
meas. (geom. mean)
Basis for effect:
growth rate
Remarks on result:
other: 1.04-2.38
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.27 mg/L
Nominal / measured:
meas. (geom. mean)
Basis for effect:
growth rate
Results with reference substance (positive control):
The results of the verification test with K2Cr2O7, carried out in period from 30.3. to 2.4. 2015, are the following:
72 hour – ErC50 = 0.79 mg·L-1 (95% confidence limit: 0.70 – 0.89 mg·L-1)

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Executive summary:

The test substance, 2-methoxy-5-nitrophenyl acetate, was tested for growth inhibition on algae Desmodesmus subspicatus. The test was performed according to method C.3. - Freshwater Algae and Cyanobacteria, Growth Inhibition Test, Commission Regulation (EC) No. 761/2009, Annex IV. The preliminary test was performed in range of test substance nominal concentrations 1 – 100 mg·L-1. The analytical results showed, that the test substance 2-methoxy-5-nitrophenyl acetate was not stable in the test medium at conditions of the test in concentration range 1 – 100 mg·L-1 . Based on the toxicity of the test substance found in preliminary test, the full test was performed in appropriate concentration range. The full test was performed in range of test substance nominal concentrations 5 – 62 mg·L-1. Samples for analytical determination were taken at the beginning, after 24 hours, 48 hours and at the end of the test. The analytical results showed that the test substance 2-methoxy-5-nitrophenyl acetate was not stable in test medium at conditions of the test. With respect to this observation the geometric mean concentrations were used for results presentation and evaluation. Test results: 72 hour – ErC50 = 1.53 mg·L-1 (geometric mean concentration) (95% confidence limit: 1.04 – 2.38 mg·L-1) 72 hour – EyC50 = 0.16 mg·L-1 (geometric mean concentration) (95% confidence limit: 0.02 – 0.38 mg·L-1) 72 hour – NOECr = 0.27 mg·L-1 (geometric mean concentration) 72 hour – NOECy < 0.18 mg.L-1