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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study according to internationally accepted guidelines and GLP compliant.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
The concentrations of test substance were not analysed in this study. Only nominal concentrations were used.
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
Test item: IMIDAZOLE ETHANOL (CAS No. 24155-42-8)
Batch No.: L36066N
Physical state: Light-yellow powder
Active ingredient content (titrimetry): 92.1%
Impurities (HPLC): 9.18%
Storage: 15-30°C

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
At 24, 48 and 72 hours after the beginning of the test the alga cell concentrations were determined by microscopically counting with a Bürker chamber.

Test solutions

Vehicle:
yes
Details on test solutions:
OECD medium was used for inoculum and test cultures according to OECD 201 guideline. Deionised water was used for preparing the media. The media was sterilized by filtration. For the solid medium of seed stock cultures 5 % agar is added to the OECD medium.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test species: Pseudokirchneriella subcapitata (Korshikov) F.Hindák
Source: National Institute of Environmental Health
The seed stock culture was maintained on solid OECD medium. The alga cells were passed from old seed stock cultures to fresh solid medium in every two or three weeks. The new seed cultures were kept under continuous illumination for five or seven days. After this grow phase they were kept in refrigerator.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
21+-2°C
pH:
The pH was measured at the beginning and the end of the test. In the beginning the pH was determined in an additionally prepared replicate. In the end the vessels were measured directly.
Nominal and measured concentrations:
The following concentrations were applied: 0.2; 0.5; 0.9; 1.8; 3.7; 7.4; 14.7 and 29.4 mg/l.
The evaluation of toxic effect was based on the nominal concentrations of test item which were modified by correction factor.
Details on test conditions:
Eight test solutions of different concentration were prepared by mixing appropriate volume of OECD medium and stock solution of the test substance. The applied concentrations were spaced by a factor 2. Range of concentration of the test item for the test was determined previously in a range-finding test. The alga cell concentration in every dilution and the control levels were 5 001 cell/ml.
Three replicates were prepared at every test and six at the control level. The vessels contained 75 ml test media.
At 24, 48 and 72 hours after the beginning of the test the alga cell concentrations were determined by microscopically counting with a Bürker chamber. The initial alga cell density was calculated from the dilution ratio of inoculum culture.

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.47 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CL
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
0.57 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.81 mg/L
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL
Details on results:
The statistical analyses of data were performed by ToxRat® software.
The NOEC and LOEC were determined with Fisher’s exact binominal test with Bonferroni correction. The results were inconclusive.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In this Freshwater Alga and Cyanobacteria, Growth Inhibition Test for “Imidazole Ethanol” (CAS No. 24155-42-8) the results indicated that the test item is hazardous to the aquatic environment [GHS Acute aquatic hazard Category Acute I. – 72 hr EC50 (for algae) ≤ 1 mg/l]