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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 Aug - 12 Sep 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
other: SEPA, The Guidelines for the Testing of Chemicals, 2004, 201 Alga Growth Inhibition Test.
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: concentrations of the test substance determined at 0, 24, 48 and 72 hours of the test
- Sampling method: separation of algae from the test medium made by syringe filters
- Sample storage conditions before analysis: none
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: nominal concentration of 100 mg/L of the test substance was prepared and stirred (via magnetic stirrer) in the dark for 72 h at 500 rpm followed by filtration using a 0.451 μm nitrocellulose membrane to make a saturated solution of the test substance in the test water.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokichnerella subcapitata
- Source (laboratory, culture collection): Institute of Hydrobiology, Chinese Academy of Sciences
- Age of inoculum (at test initiation): 3 days
- Method of cultivation: algae were inoculated in 250 mL glass flask with the concentration of 10^4 cells/mL, incubated in 3 days and then inoculated to another flask.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
none
Test temperature:
23.3°C - 23.5 °C
pH:
7.74 - 9.12
Nominal and measured concentrations:
Range finding test: 0, 25, 50, 100 % of saturated solution
Limit test: 0, 100 mg/L (nominal, saturated solution)
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml glass conical flasks, closed with Parafilm, shaked at a speed of 130 rpm
- Initial cells density: 10^4 cells/mL
- Control end cells density: 1.22 x 10^6
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity and quality: uniform fluorescent illumination; 5024 - 5497 Lux; cool white light

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: counting chamber; at 0, 24, 48 and 72 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 0, 25, 50, 100 % of saturated solution
- Results used to determine the conditions for the definitive study: EC50 > 100 % saturated solution
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: test material (saturated solution)
Basis for effect:
growth rate
Remarks on result:
other: Measured concentrations of the test substance were below the limit of detection of 89.6 ng/mL
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: test material (saturated solution)
Basis for effect:
growth rate
Remarks on result:
other: Measured concentrations of the test substance were below the limit of detection of 89.6 ng/mL
Details on results:
Based on growth rate and biomass: the 72h-ErC50 and LOEC values of the test substance to Pseudokirchneriella subcapitata was above the concentration of the saturated solution (measured concentration below the LOD2 of 89.6 ng/mL).
Results with reference substance (positive control):
EC50 (growth rate) = 0.83 mg/L
Reported statistics and error estimates:
The difference in the average specific growth rate between the control group and treatment groups were determined using t-Test.

Table 1. Cell density in limit test:

Treatment group Cell density (cell/mL)
0 h 72 h
Control 10000 1226167
100 mg/L (nominal, saturated solution) 10000 1172833

Table 2.Measured concentrations of the test substance in limit test:

Treatment group Measured concentrations [mg/L]
0 h 48 h
Control not detected not detected
100 mg/L (nominal, saturated solution) not detected not detected

Description of key information

EC50 (72 h) > 100 mg/L (nominal) for Pseudokirchneriella subcapitata based on growth rate (OECD 201)

LOEC (72 h) > 100 mg/L (nominal) for Pseudokirchneriella subcapitata based on growth rate (OECD 201)

Key value for chemical safety assessment

Additional information

The toxicity of Reaction mass of 1,1'-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromo-2-methylpropoxy)benzene] and 1,3-dibromo-2-(2,3-dibromo-2-methylpropoxy)-5-{2-[3,5-dibromo-4-(2,3,3-tribromo-2-methylpropoxy)phenyl]propan-2-yl}benzene was tested on algae according to OECD 201 and GLP (Jing, 2014). The freshwater algae Pseudokirchneriella subcapitata was exposed to the test substance for 72 h, at the nominal test concentration of 100 mg/L. The test item solution was stirred and subsequently filtered in order to obtain a saturated solution as the test item is poorly soluble in saltwater. An analytical monitoring was performed via UPLC. Based on growth rate and biomass, the EC50 (72 h) and LOEC (72 h) values were above the concentration of the saturated solution (measured concentration below the LOD of 89.6 ng/mL).