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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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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:
other: GLP guideline study. The substance caused a decrease in pH of the test solution at the highest test concentrations. The test was repeated with the two highest test concentration (pH was adjusted).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Maleic acid
- Analytical purity: 99.7 %
- Lot/batch No.: LPMS3A1015

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was prepared by mixing 250 mg o with 25 ml test medium. The test solutions were prepared separately by dilution of the stock solution.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Source (laboratory, culture collection): Norwegian Institute for Water Research, Oslo, Norway

Study design

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

Test conditions

Test temperature:
22.6 - 23.4 °C
pH:
initial test: 4.64 - 8.31
repeated test: 7.72 - 8.36
Nominal and measured concentrations:
Nominal test concentrations:
2, 5, 12.5, 31.25 and 78.13 mg/l

Mean measured concentrations:
2.04, 5.13, 12.78, 31.76, 79.72 mg/l

Repeated test:
31.25 and 78.13 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: conical flasks (250 ml)
- Fill volume: 150 ml
- Initial cells density: 10000
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: the test medium was prepared according to OECD guideline 201


OTHER TEST CONDITIONS
- Adjustment of pH: yes at 31.25 and 78.13 mg/l
- Photoperiod: continous illumination
- Light intensity and quality: 7240 - 7390 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: cell growth (haemocytometer) after 24, 48 and 72 hours of exposure.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5
Reference substance (positive control):
yes
Remarks:
Potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
11.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC20
Effect conc.:
22.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
74.35 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
The substance caused a decrease of the pH in the test medium. Diefferences in the algal grwoth between the initial test and the repeated test were ascribed to the low pH at test concentrations of 31.25 and 78.13 mg/l in the initial test.

Applicant's summary and conclusion