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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:
1993
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was given a reliability rating of 1 because it followed a standard test guideline, which describes a procedure to evaluate this endpoint, and the results were reviewed for reliability and assessed as valid. The study was also conducted under GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
Individual treatment concentrations were prepared as water accommodated fractions (WAF). Control and dilution water were laboratory prepared algal nutrient medium. Test substance was mixed with dilution water in sealed vessels for approximately 24 hours, and the mixtures were allowed to settle for approximately 1 hour prior to drawing off the aqueous phase for testing.
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
Algal cells obtained from testing laboratory cultures. Original algal cultures obtained from American Type Culture Collection (ATCC 22662).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
Temperature was 22 to 24 Deg C.
pH:
The pH ranged from 7.2 to 7.7 at test initiation and 7.2 to 10.2 at test termination.
Dissolved oxygen:
Not applicable
Salinity:
freshwater
Nominal and measured concentrations:
Nominal loading rates were 0.1, 0.4, 1.0, 3.0, and 10 mg/L. Only the 0 and 72 hours samples from the 3.0 and 10 mg/L treatments were analyzed yielding mean measured concentrations of 3.2 and 8.2 mg/L, respectively.
Details on test conditions:
Lighting was continuous at approximately 3000 lux.

Test vessels were sealed 300 ml conical flasks that were completely filled with test solution. The treatment and control flasks were inoculated with algal cells to yield initial concentrations ranging from 3200 to 5000 cells/ml. Uninoculated flasks were used to determine particle counts without algal cells. Biomass was calculated as area under the growth curve.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 - < 3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 - < 3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
ca. 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
ca. 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
See Tables Below
Reported statistics and error estimates:
EL50 values estimated by visual inspection of data to determine range of loading rates, which bracketed a 50% reduction in biomass and growth rate. ANOVA and Williams test used to determine NOELs.

Nominal Loading 72 h 
(mg/L)  % Inhibition
   
Control N/A
0.1 -14.0
0.4 -27.0
1.0 -8.0
3.0 97.0
10.0 100.0

Nominal Loading Conc.  Conc. 
(mg/L)  0 hr (cells/mL) 72 hr (cells/mL)
     
Control 3.2xE3 3.7xE5
0.1 4.6xE3 4.2xE5
0.4 5.3xE3 4.7xE5
1.0 5.4xE3 4.0xE5
3.0 5.2xE3 9.3xE5
10.0 3.5xE3 0.0
Validity criteria fulfilled:
yes
Conclusions:
The hydrocarbons, C10, aromatics, >1% naphthalene, freshwater 72-hr EL50 value for Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) is 1.0 to 3.0 mg/l based on both growth rate and biomass. The hydrocarbons, C10, aromatics, >1% naphthalene, freshwater 72-hr NOELR (No Observed Effect Loading Rate) value for Pseudokirchneriella subcapitata is approximately 1.0 mg/l based on both growth rate and biomass.
Executive summary:

The hydrocarbons, C10, aromatics, >1% naphthalene, freshwater 72-hr EL50 value for Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) is 1.0 to 3.0 mg/l based on both growth rate and biomass. The hydrocarbons, C10, aromatics, >1% naphthalene, freshwater 72-hr NOELR (No Observed Effect Loading Rate) value for Pseudokirchneriella subcapitata is approximately 1.0 mg/l based on both growth rate and biomass.

Description of key information

Water accommodated fractions of hydrocarbons, C10, aromatics, >1% naphthalene, produced a freshwater 72-hr EL50 value for Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) of 1.0 to 3.0 mg/L based on both growth rate and biomass. The 72-hr NOELR (No Observed Effect Loading Rate) value for Pseudokirchneriella subcapitata is approximately 1.0 mg/L based on both growth rate and biomass.

 

In a supporting study, water accommodated fractions of hydrocarbons, C10, aromatics, >1% naphthalene, produced a freshwater 72-hr EL50 value for Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) of 11 mg/L and 8.5 mg/L based on growth rate and biomass, respectively. The 72-hr NOELR (No Observed Effect Loading Rate) value for Pseudokirchneriella subcapitata is 2.5 mg/L based on both growth rate and biomass.

Key value for chemical safety assessment

Additional information

Water accommodated fractions of hydrocarbons, C10, aromatics, >1% naphthalene, produced a freshwater 72-hr EL50 value for Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) of 1.0 to 3.0 mg/L based on both growth rate and biomass. The 72-hr NOELR (No Observed Effect Loading Rate) value for Pseudokirchneriella subcapitata is approximately 1.0 mg/L based on both growth rate and biomass.