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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:
January 21, 2011 - February 11, 2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
(see § Overall remarks)
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
yes
Remarks:
(see § Overall remarks)
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
The test item concentration was checked at initiation and every 24h along the test.
Vehicle:
no
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Origin: the strain was provided by the Muséum National d’Histoire Naturelle (Paris, France) and regularly sub-cultured in the OECD medium at the
Phytosafe site.
The inoculum culture was prepared 2-4 days before the start of the test and incubated under the same conditions as the test cultures such to adapt
the test algae to test conditions and ensure that the algae were in the exponential growth phase when used to inoculate the test solutions.
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Remarks on exposure duration:
degraded btw 48-72h
Post exposure observation period:
no
Test temperature:
Between 21 and 24°C.
pH:
8.3-8.9
Nominal and measured concentrations:
Nominal:
Range-finding test: 0.01 – 0.1 – 1.0 – 10.0 and 99.8 mg/L
Limit test: 99.8 mg/L

Measured:
At limit-test test initiation, 115% of nominal value. At 24h, 122 % of nominal value. At 48h, 107 % of nominal value. At 72h, <1% of nominal value due to high biodegradability.
Details on test conditions:
MEASUREMENTS AND ASSESSMENTS
Algal biomass
The algal biomass in each flask was determined daily over the test period using small volumes removed from the test solution by pipette.
These volumes were not replaced.
The numeration was done using an electronic cell counter (Coulter Counter ZM). The results were expressed as cells per liter of solution.

pH values
The pH of the solutions was measured at the beginning and at end of test. The pH of the control medium was not to increase by more than 1.5 units
during the test.

Other observations
The inoculum culture was examined microscopically to verify that it was normal and healthy in appearance and to detect any abnormal appearance of the algae (as may be caused by exposure to the test substance) at the end of the test.

TEST SYSTEM
- Test vessel: Glass Erlenmeyer flasks, capped with air-permeable stoppers

GROWTH MEDIUM
- Standard medium used: OECD medium

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ISO 8692 reconstituted water

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous, uniform fluorescent illumination
- Light intensity and quality: 60-120 µE.m-2.s-1

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10 in range-finding
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:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
VALIDITY OF THE TEST RESULTS
The test was considered as valid in the light of the following criteria:
- The biomass in the control cultures increased exponentially by a factor of at least 16 over the 72-hour test period.
- The mean coefficient of variation for section-by-section specific growth rates in the control cultures did not exceed 35 % (this criterion applies to the mean value of the coefficients of variation calculated for replicate control cultures).
- The coefficient of variation for average specific growth rates over the entire test period in replicate control cultures did not exceed 7 %.
Additionally, the EC50-72 h for Potassium dichromate was between 0.6 and 1.0 mg/L for the specific growth rate and between 0.2 and 0.75 mg/L for the yield. The results fulfilled the validity criteria based on Phytosafe historical data.
For the limit test, the test item treatment remained stable for the first 48 h of testing, then after the test item was decreased to almost zero in every replicate unit. Despite this, and because semi-static methodology was not applicable to such a high biodegradable substance, the nominal concentration was considered as 100 mg/L.
Results with reference substance (positive control):
EC50-72 h was between 0.6 and 1.0 mg/L for the specific growth rate and between 0.2 and 0.75 mg/L for the yield
Validity criteria fulfilled:
yes
Conclusions:
ErC50 based on specific growth rate ≥ 100 mg/L.
EyC50 based on yield ≥ 100 mg/L.
Based on nominal levels as the substance degraded entirely between 48 and 72h.
Executive summary:

 

Phytosafe Study Number:

10-27-075-ES

Study:

Freshwater algae, Growth inhibition test with Calcium tartrate (OECD 201, March 2006)

Test item:

Calcium tartrate

Batch No.Camp 09.10

Nominal test concentrations:

Range-finding test:– 0.1 – 1.0 – 10.0 and 99.8 mg/L

Limit test: 99.8 mg/L

Test dates:

January 21 to February 11, 2011

Length of test:

72-hour exposure period

 

Test organisms

Desmodesmus subspicatus

Source

Muséum National d’Histoire Naturel (Paris, France)

Control

Water

Toxic standard

Potassium dichromate

EC50for specific growth rate between 0.6 and 1.0 mg/L

EC50for yield between 0.20 and 0.75 mg/L

 

Results(1)

Range-finding test

Limit test

Specific growth rate

NOEC 72 h ≥ 100 mg/L

NOEC 72 h ≥ 100 mg/L

Yield

NOEC 72 h ≥ 100 mg/L

NOEC 72 h ≥ 100 mg/L

Recovery of the test item at the end of test

41 % for the 99.8 mg/L test item treatment(1)

> 100 % for the first two days of testing and then almost zero at the end of test(2)

(1)    See deviation No.1 from the study plan

(2)    See deviation No.2 from the study plan

Description of key information

  Tartaric acid and its salts are not expected to be toxic to algae.

Key value for chemical safety assessment

Additional information

Based on the data obtained from short-term assays conducted on several algae strains, tartaric acid and its salts are not expected to be toxic to this aquatic target.

Based on the assumption that in dilute aqueous conditions of defined pH, a salt will be fully dissociated and will behave no differently to the parent acid at identical concentration of the particular speciated form present, the aquatic toxicity of tartaric acid salts (i.e. monosodium, monopotassium, sodium potassium, sodium, potassium and calcium tartrate) may be assessed using data specific for tartaric acid. Therefore, also the tartaric acid salts are deemed to be non-toxic to aquatic algae.