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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)
Rationale for reliability incl. deficiencies:
comparable to guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Lot No 503881
Specific details on test material used for the study:
Lot no 503881

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Water samples were collected from freshly prepared batch (or pooled replicate samples as in
the Rainbow trout) of test solution for each treatment group and control at test initiation. All samples
were collected from mid-depth in the test solutions, placed in glass vials, and processed immediately
for analysis.

Test solutions

Vehicle:
yes
Details on test solutions:
A primary stock solution was prepared in freshwater algal media at a nominal
concentration of 5.0 mg/L. The stock was sonicated for ~ 5 minutes and inverted to mix.
The primary stock solution appeared clear and colorless. Proportional aliquots of the primary
stock solution were diluted with freshwater algal media to prepare the 0.063, 0.13, 0.25, 0.50,
1.0 and 2.0 mg/L test solutions. The test solutions appeared clear and colorless.
For the recovery phase, the negative control and the nominal test concentrations of
0.25, 0.50, 1.0 and 2.0 mg/L were selected. The negative control and each test concentration
was tested as a single flask and exposed to untreated freshwater algal medium under test
conditions for up to ten days.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Species: Freshwater alga (Pseudokirchneriella subcapitata)
Source: University of Toronto Culture Collection (UTCC); Department of Botany
25 Willcocks St., Toronto, ON, Canada M5S 3B2

Study design

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

Test conditions

Test temperature:
24ºC, consistent within +/- 2ºC (Constant temperature chamber)
pH:
7.4 - 8.0
Nominal and measured concentrations:
Nominal concnetrations: 0, 0.063, 0.13, 0.25, 0.5, 1.0, 2.0 mg/L
Measured concentrations: 0.086, 0.15, 0.25, 0.53, 1.0, 1.7 mg/L
Details on test conditions:
Species: Freshwater alga (Pseudokirchneriella subcapitata)
Source: University of Toronto Culture Collection (UTCC); Department of Botany
25 Willcocks St., Toronto, ON, Canada M5S 3B2
Photoperiod: 24-hrs light
Lighting: Cool-white fluorescent lights (lux 6000 ± 10%)
Test Vessels: 250 mL Erlenmeyer flasks plugged with foam stoppers, shaken continuously at
100 rpm on a rotational shaker.
Test Volume: 100 mL
Initial Cell Density: 10,000 cells/mL
Number of Replicates: Dose-response test – 2
Dilution Water: Standard freshwater algal nutrient media prepared in NANOpure® water, as
outlined in ASTM 1218-90E (4).
Test Temperature: 24ºC, consistent within +/- 2ºC (Constant temperature chamber)
Test Solutions pH: 7.4 – 8.0
Exposure Period: 96 hours
Effect: Inhibition in growth as determined by cell counts, area under the growth
curve (biomass), and growth rate.
Measurements: Temperature 2x daily; pH at test initiation and termination.
Procedure: Cell counts conducted using an Electron Particle Counter at 96 hours. Percent
inhibition of growth and EC50 calculated based on cell density, biomass and
growth rate at 96 hours.

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
0.103 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
0.064 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
0.278 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
see appended image

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The calculated ErC50 value for Maropitant in algae following a 96 hour exposure is 0.278 mg/L with a 95% confidence interval of 0.22-0.352. This result is relevant for classification in accordance with 1272/2008/EC.