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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2006, including correction of 2011
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Remarks:
however, a suitable method of compound specific analysis could not be developed for the relevant concentration range of this study
Vehicle:
no
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.61 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.32 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield

Algal cells aggregated at concentrations equal or greater than 0.10 mg/L. Consequently, algal cell density measurements based on cell counts might have been unreliable.

Validity criteria fulfilled:
yes
Conclusions:
With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates were significantly different from that of the control group in the examined concentration range of 1.0 - 3.2 mg/L (nominal). The NOEC was determined as 0.32 mg/L (nominal) and the LOEC was determined as 1.0 mg/L (nominal). The 0-72 h yields were significantly different from that of the control group in the examined nominal concentration range of 0.32 – 3.2 mg/L (nominal). The NOEC was determined as 0.10 mg/L (nominal) and the LOEC was determined as 0.32 mg/L (nominal). Aggregated cells were observed to be present in the test cultures at concentrations equal or greater than 0.10 mg/L. Consequently, the algal cell density measurements which were based on cell counts might have been unreliable.
Executive summary:

The effect of the test item on algae was assessed in a GLP and guideline study (OECD testing guideline 201) using the unicellular green alga Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum), over an exposure period of 72 hours. A test item specific analytical method could not be develped for the relevant concentration range of this study. Therefore it was considered appropriate to calculate the results based on nominal test concentrations. All test and control cultures were inspected microscopically at 72 hours. After 72 hours there were no abnormalities detected in the control or test cultures at 0.032 mg/L. However, aggregated cells were observed to be present in the test cultures at 0.10, 0.32, 1.0 and 3.2 mg/ L. The EC50(growth rate) was determined as 1.8 mg/L (95% confidence limits could not be determined because the values did not fit the models available for calculation), the EC50 (yield) was 0.61 mg/L (95% CI 0.50 - 0.75 mg/L). The NOEC (growth rate) was 0.32 mg/L, with the LOEC at 1.0 mg/L; the NOEC (yield) was 0.10 mg/L with the LOEC at 0.32 mg/L.

Endpoint:
effects on growth of an additional algal species
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
September 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
no guideline followed
Principles of method if other than guideline:
Phaeodactylum tricornutum (P. tricornutum) wild type 646 strain were grown in f/2 medium as follows: control group (f/2 medium), CB[6] group (f/2 medium with 3 different concentrations of CB[6], CB[7] group (f/2 medium with 3 different concentrations of CB[7], and CB[8] group (f/2 medium with 2 different concentrations of CB[8]. The cell cultures were grown over 11 days and the concentration of algae cells was determinied by optical density (OD) which was measured at 730 nm by plate reader
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Phaeodactylum tricornutum
Details on test organisms:
wild type 646 strain
Test type:
static
Water media type:
saltwater
Limit test:
no
Total exposure duration:
11 d
Test temperature:
room temperature
Nominal and measured concentrations:
Nominal concentrations tested: 100 µM, 200 µKm, 400 µM
Details on test conditions:
Algal cell cultures were grown over 11 days in sterile Nunc Cell Culture Treated EasYFlasks. Suspension cultures were maintained at room temperature and agitated using a rotating shaker at 20 RPM with constant light illumination. Aliquots of 200 µL were removed and pitpetted into Corning 3603 black-sided clear bottomed plates. Optical density measurements were made at 730 nm using a CLARIOstar Microplate Reader.
The f/2 medium was prepared according to Guillard and Ryther (1962).
Reference substance (positive control):
no
Key result
Duration:
11 d
Dose descriptor:
NOEC
Effect conc.:
400 µmol/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Validity criteria fulfilled:
not specified
Conclusions:
The NOEC (11 days) of Cucurbit[6]uril towards Phaeodactylum tricornutum was 400 µM (ca. 400 mg/L)
Executive summary:

The growth rate of P. tricornutum in CB[6] added f/2 medium did not change when the concentration of CB[6] varied from 100 µM to 300 µM.

Endpoint:
effects on growth of an additional algal species
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
September 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
no guideline followed
Principles of method if other than guideline:
Phaeodactylum tricornutum (P. tricornutum) wild type 646 strain were grown in four different mediums as follows: control group (f/2 medium), CB[6] group (f/2 medium with 3 different concentrations of CB[6], CB[7] group (f/2 medium with 3 different concentrations of CB[7], and CB[8] group (f/2 medium with 2 different concentrations of CB[8]. The cell cultures were grown over 11 days and the concentration of algae cells was determinied by optical density (OD) which was measured at 730 nm by plate reader
GLP compliance:
no
Analytical monitoring:
no
Test organisms (species):
Phaeodactylum tricornutum
Test type:
static
Water media type:
saltwater
Limit test:
no
Total exposure duration:
11 d
Key result
Duration:
11 d
Dose descriptor:
NOEC
Effect conc.:
100 µmol/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
11 d
Dose descriptor:
EC50
Effect conc.:
> 400 µmol/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Validity criteria fulfilled:
not specified
Conclusions:
The NOEC (11 days) of CB[7] towards P. tricornutum was at 100 µM. The EC50 was higher than 400 µM.
Executive summary:

CB[7] reduced the growth rate of P. tricornutum in f/2 medium at concentrations of 200 and 400 µM. 100 µM were without effect.

Endpoint:
effects on growth of an additional algal species
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
no guideline followed
Principles of method if other than guideline:
Phaeodactylum tricornutum (P. tricornutum) wild type 646 strain were grown in four different mediums as follows: control group (f/2 medium), CB[6] group (f/2 medium with 3 different concentrations of CB[6], CB[7] group (f/2 medium with 3 different concentrations of CB[7], and CB[8] group (f/2 medium with 2 different concentrations of CB[8]. The cell cultures were grown over 11 days and the concentration of algae cells was determinied by optical density (OD) which was measured at 730 nm by plate reader
GLP compliance:
no
Test organisms (species):
Phaeodactylum tricornutum
Test type:
static
Water media type:
saltwater
Limit test:
no
Total exposure duration:
11 d
Test temperature:
room temperature
Key result
Duration:
11 d
Dose descriptor:
NOEC
Effect conc.:
200 µmol/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Validity criteria fulfilled:
not specified
Conclusions:
There was no obvious growth rate change of P. tricornutum at 100 and 200 µM in f/2 medium. Undissolved CB[8] was found under the microscope.

Description of key information

Key values are taken from a GLP study performed in accordance with OECD test guideline 201, EU method C3 and US EPA procedure OCSPP 850.5400

Key value for chemical safety assessment

EC50 for freshwater algae:
1.8 mg/L
EC10 or NOEC for freshwater algae:
0.32 mg/L
EC10 or NOEC for marine water algae:
100 mg/L

Additional information

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata over an exposure period of 72 hours.


With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates were significantly different from that of the control group in the examined concentration range of 1.0 to 3.2 mg/L (nominal). The NOEC was determined as 0.32 mg/L (nominal) and the LOEC was determined as 1.0 mg/L (nominal). The 0-72 h areas and yield were significantly different from that of the control group in the examined nominal concentration range of 0.32 to 3.2 mg/L (nominal). The NOEC was determined as 0.10 mg/L (nominal) and the LOEC was determined as 0.32 mg/L (nominal).


The EC50 for growth rate was 1.8 mg/L, and for yield 0.61 mg/L. At any concentrations equal or greater 0.10 mg/L chuffed and aggregated cells were observed.


Exposure over 11 days to nominal concentrations of 100 mg/L or higher of CB[6], CB[7] or CB[8] had however no effects on the growth rate of Phaeodactylus tricornutum in an earlier, non-GLP study suggesting that nutrient depletion may have caused the effects in the GLP study.