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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
other: United States Environmental Protection Age- ncy (1971) Algal Assay Procedure Bottle Test.
Qualifier:
equivalent or similar to guideline
Guideline:
other: U.S. Environmental Protection Agency(1978) The Selenastrum capricornutum Printz Alagal Assay Procedure Bottle Test, Experimental Design, Application and Data Interpretation
Principles of method if other than guideline:
investigated the effect of washing detergent on the growth of algae as a test organism. In particular, we compared the effects of detergents and their components (surfactants and auxiliaries) on algae.
GLP compliance:
no
Analytical monitoring:
no
Details on test solutions:
The test substance was added to the medium to prepare a test solution.
The initial pH of the test solution was adjusted to 7.4 ± 0.1 using 0.1 specified hydrochloric acid or 0,1 specified sodium hydroxide solution.
Test organisms (species):
other: Selenastrum capricornotum, Mycrocystystis aeruginosa and Nitzschia fonticola
Details on test organisms:
- Culturing media and conditions: modified version of Hughes, Gorhamand Zehnderg) No. 11 culture medium.
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
24 ± 2 ° C
Details on test conditions:
TEST SYSTEM
- Test vessel: 500 ml of triangularflasko, and silicosen 13 (Shinetsu Polymer Co., Ltd., Cap), place in a rotary shake that rotates 90 times per minute under a white fluorescent lamp (Sanline Ace, Nittate Seisakusho) that irradiates from the upper part.
- Initial cells density: The algae in the logarithmic growth phase in the preculture were concentrated by sedimentation (about 7,000 × 9,10 minutes) and diluted in a new culture, and used for the seeding of the test culture. The planting concentration was 0.7 ± 0.2 mg dry weight
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used:
Compound Concentration (mg/L)
NaNO3 99.2
K2HPO4 7.8
MgSO4*7H2O 15
CaCl2*2H2O 7.2
Na2CO3 4
Na2SiO3*9H2O 11.6
Na2EDTA*2H2O 1
Citric acid 1.2
Fe citrate 1.
Gaffron’s micronutrients stock solution 0.08

EFFECT PARAMETERS MEASURED :
- Determination of cell concentrations: by the intensity of fluorescence emitted by chlorophyll (Model 10000R Firefly Luminometer, Turner Design) every 12 hours
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

CULTURING APPARATUS
-Details on culturing apparatus used:
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 800 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Conclusions:
Exposure of three green algaaes for 72h to Na2CO3 resulted in a EC50 >800 mg/L based on the inihibition of the growth rate
Executive summary:

A study was conducted exposing three different green-algae, Selenastrum capricornotum, Mycrocystystis aeruginosa and Nitzschia fonticola to sodium carbonate, chosen as builder in the formulations of laundry detergents.

Tests were conducted followinf the EPA (1971) Algal Assay Procedure Bottle test. Results showed an EC50 > 800 mg/l after 72 h of exposure.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2014
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Investigate the toxic effects of alkaline salt on algal photosynthesis, we used Na2CO3 to stress C. reinhardtii, a model organism of single cell, to determine the algal growth, ROS production, as well as changes of photosynthetic pigments and chlorophyll fluorescence
GLP compliance:
no
Specific details on test material used for the study:
no data
Analytical monitoring:
no
Details on sampling:
not applicable
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION: test item was added in the test culture at the desired concentration
Test organisms (species):
Chlamydomonas reinhardtii
Details on test organisms:
TEST ORGANISM
- Common name: single-cell green alga
- Strain: CC-125 wild type mt+ [137c]
- Source (laboratory, culture collection): Duke University, Durham, NC, USA
- Method of cultivation: grown in 25 mL liquid Tris-acetate- phosphate (TAP) medium (Na+ only 0.26 mM), put on a shaking table with 120 rpm, and kept at a light (16 h)/dark (8 h) regime at 23◦C, with an illumination of 100 μmol m-1 s-1.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
24 h
Test temperature:
23 C
pH:
7.9-10.5 depending on the exposure concentration
Nominal and measured concentrations:
10 mM, 25 mM, 50 mM and 150 mM Na2CO3
Details on test conditions:
TEST SYSTEM
- Test vessel: suspended in 25 mL freshly prepared medium with different salt concentration
- Initial cells density: 6 × 106 cells/mL
- Control end cells density: around 10.5 × 106 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: liquid Tris-acetate- phosphate (TAP) medium (Na+ only 0.26 mM)

OTHER TEST CONDITIONS
- Photoperiod: 14 h light/8 h dark/2 h light
- Light intensity and quality: 100 μmol m-1 s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: blood cell counting plate, with each value being the means of 6 repeats.
- Chlorophyll measurement: fluorescence
- Other: photosynthetic pigment
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
LOEC
Effect conc.:
1 060 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
24 h
Dose descriptor:
LOEC
Effect conc.:
15 898.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Chlorophyll
Duration:
12 h
Dose descriptor:
LOEC
Effect conc.:
5 300 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Phosynthetic activity Fv/Fm
Details on results:
Under Na2CO3 stress, the absorbance peaks were not markedly changed at 10 mM, but they were declined at 25 mM. In the treatment with 50 mM Na2CO3, the absorbance peak at 457 nm disappeared after 1 h, while a new peak at 416 nm appeared after 2 h. The shapes of peaks were significantly changed in the treatment with Na2CO3 at 150 mM, and new absorbance peaks at 416 nm, 443 nm and 640 nm were reduced gradually with prolonging the treatment time.
Executive summary:

A study was conducted exposing the green algae, C. reinhardtii, for 24h to Na2CO3 at the concentration range of 10-150 mM. Results showed that cell density was significantly affected at the lowest concentration tested, determining a LOEC of 10 mM (1060 mg/L). Chlorophyll content was instead significantly decreased only at the highest concentration tested, determining a LOEC of 150 mM (15898.8 mg/l).

Description of key information

The study does not need to be conducted as in the aquatic environment; sodium carbonate is dissociated into sodium and carbonate ions. Both ions originally exist in nature, and their concentrations in surface water are dependent on various factors, such as geological parameters, weathering and human activities. Therefore, there is a continuous source of both ions into the environment and have been measured extensively in aquatic ecosystems.  Non-performance of an algal toxicity study was also accepted in earlier evaluation (OECD, 2002): since results can be predicted based on the increase of the pH of the test solution, the results will depend on the algal species selected, the composition of the test medium and probably the growth conditions before the start of the test. The results cannot be extrapolated directly to aquatic ecosystems because the growth conditions are in many cases not comparable to the laboratory conditions.

Two reliable studies are available (K2) exposing the green algaes to sodium carbonate.

One study (Zou, 2014) exposed the green algae, Chlamydomonas reinhardtii, for 24h to Na2CO3 at the concentration range of 10-150 mM. Results showed that cell density was significantly affected at the lowest concentration tested, determining a LOEC of 10 mM (1060 mg/L). Chlorophyll content was instead significantly decreased only at the highest concentration tested, determining a LOEC of 150 mM (15898.8 mg/l).

The second available reliable study (Yamane, 1984) was conducted exposing three different green-algae, Selenastrum capricornotum, Mycrocystystis aeruginosa and Nitzschia fonticola to sodium carbonate, chosen as builder in the formulations of laundry detergents. Tests were conducted following the EPA (1971) Algal Assay Procedure Bottle test. Results showed an EC50 > 800 mg/l after 72 h of exposure

Key value for chemical safety assessment

Additional information