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Ecotoxicological information

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:
04 February 2013 - 18 October 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:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to
Guideline:
other: US EPA Office of Chemical Safety and Pollution Prevention (OCSPP) method 850.4500 (algal toxicity)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0 (control), 50, 100, 200, 400, and 800 mg/L
- Sampling method: An aliquot (2 mL) of the sample was taken and fortified if required. Hexane (20 mL) was added and shaken for 90 seconds to mix. The hexane layer was analysed by GC-ECD.
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: CCAP 278/4
- Age of inoculum: Three days (secondary cultures, in the log phase of growth)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
0 hours: 22.1 - 22.3°C
96 hours: 23.3 - 23.7°C
pH:
0 hours: 7.38 - 7.65
96 hours: 9.70 - 10.32
Nominal and measured concentrations:
Nominal: 0 (Control), 50, 100, 200, 400, and 800 mg/L
Initial measured: 0 (not detected), 18.2, 27.9, 31.7, 54.5, and 89.3 mg/L
Measured concentration, 96 hours: 0, Geometric mean measured concentrations: 0, 2.7, 10.4, 11.8, 22.1, 6.0 mg/L

LOQ was the level of quantification, 0.8 mg/L
Where values were below the LOQ, geometric means were calculated using half of the LOQ, 0.4 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass bottles, 250 mL total volume. Fill volume = 100 mL; headspace = 150 mL. Bottles were sealed with parafilm and plastic lids.
- Aeration: Gaseous exchange between the algal suspension and the headspace was ensured by the use of an orbital shaker, oscillating the test vessels at nominally 100 cycles per minute.
- Initial cells density: Approximately 1 x 10^4 cells/mL
- Control end cells density: 392131 cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous illumination
- Light intensity and quality: nominally 4300 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: Coulter Z Series Particle Count and Size Analyser

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: 1.0, 10, 100, 1000 mg/L
- Results used to determine the conditions for the definitive study: Yes
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 22.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 22.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
22.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: Growth rate and yield (biomass)
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 89.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 89.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 89.3 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
> 54.5 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: growth rate, biomass (in terms of cell density), and yield (cell number)
Details on results:
In samples of freshly prepared media, the measured concentrations of 2-bromo-3,3,3- trifluoropropene ranged between 11 and 37% of their nominal values. After 96 hours, the measured concentrations had decreased to values ranging from below the limit of quantitation of the analytical method (0.8 mg/L) to 4% of nominal. The low initial measured concentrations and the losses observed were expected based on the nature and behaviour of the test substance. These results indicate that the objective was achieved, and the test system was able to reflect the behaviour of the test substance, in terms of indicating that it is not possible to maintain test concentrations under realistic conditions.

The geometric mean measured concentration for the top exposure group (nominally 800 mg/L) was lower than the mean measured concentration of the second-highest exposure group (nominally 400 mg/L) due to a low measured concentration in expired media (the 800 mg/L level was found to be below the limit of quantitation whereas the 400 mg/L level was 8.99 mg/L in expired media). With respect to growth rate, yield and biomass, the 400 mg/L nominal exposure level was considered to be the No Observed Effect Concentration (NOEC). Slight inhibition was observed in the 800 mg/L nominal exposure level; 9% inhibition of growth rate, 27% inhibition in terms of biomass / cell density and 28% inhibition in terms of yield were observed at this level. On the basis that less than 50% inhibition was observed at each level tested, for the purposes of hazard assessment the EC50 is reported as (greater than) the highest mean concentration recorded, rather than the measured concentration of the highest nominal concentration tested.
Validity criteria fulfilled:
yes
Conclusions:
After 96 hours of exposure, in terms of geometric mean measured concentration, the EC50 values for average specific growth rate, biomass (in terms of cell density) and yield were >22.1 mg/L. For all parameters, the “no observed effect concentration” (NOEC) was 22.1 mg/L.

Description of key information

EC50, 96 hours > 22.1mg/L (in terms of specific growth rate, biomass, and yield).

NOEC, 96 hours = 22.1 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
22.1 mg/L

Additional information

An algal inhibition study was conducted (Huntingdon Life Sciences, 2013) to determine the effect on aquatic plants following exposure to 2-bromo-3,3,3-trifluoropropene. The study was performed according to EC method C3, OECD method 201, and US EPA Office of Chemical Safety and Pollution Prevention (OCSPP) method 850.4500. The study was conducted in compliance with GLP. The test material is highly volatile and would not be expected to reside in the water phase for long following an environmental release; for this reason the study was performed using sealed vessels to prevent loss of the test material, but with a large headspace (more than 50% of the test media volume) in order to reflect the anticipated real-world situation.

The measured concentrations of 2-bromo-3,3,3-trifluoropropene ranged between 11 and 37% of their nominal values at the start of the test and decreased to range from below the limit of quantitation of the analytical method (0.8 mg/L) to 4% of nominal after 96 hours. Quoted endpoints (EC50, NOEC, etc.) for the study were based on the geometric mean of measured concentrations of freshly-prepared and expired (96-hours old) media; where the measured concentration was below the limit of quantitation, a concentration of 0.4 mg/L (half of the LOQ) was used for the mean calculation.

After 96 hours of exposure, in terms of geometric mean measured concentration, the EC50 values for average specific growth rate, biomass (in terms of cell density) and yield were >22.1 mg/L. For all parameters, the “no observed effect concentration” (NOEC) was 22.1 mg/L.