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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Experimental data of various test chemicals
Justification for type of information:
Data for the target chemical is summarized from data from handbook or collection of data
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
other: as mentioned below
Principles of method if other than guideline:
WoE report is based on two toxicity to aquatic algae studies as-
1. and 2.
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
not specified
Details on test solutions:
1) The stock solution (10 mg/L) was prepared by dissolving yellow powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.
2)The test item was prepared by adding 12 mg of test item in 240 ml of BBM to get the final concentration of 50mg/L. This stock solution was kept for stirring for 30 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment.
2) The test item was prepared by adding 12 mg of test item in 240 ml of BBM to get the final concentration of 50mg/L. This stock solution was kept for stirring for 30 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment.
Test organisms (species):
other: 1) Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) 2) Chlorella vulgaris
Details on test organisms:
1) TEST ORGANISM
- Common name:
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Initial biomass concentration: 5x10(3) cells /ml
- Method of cultivation: No data available

2) The fresh water green alga Chlorella vulgaris, was used as the test organism. Sterile, unicellular, liquid cultures of algae.
The culture was examined under the microscope to confirm that it was unicellular, healthy and not contaminated.
The medium to be used for the growth of algae was Bold’s Basal Medium (BBM). It is a medium composed of macronutrients, micronutrients, alkaline EDTA solution and Iron solution. Stock solution of each of these was prepared separately and then a complete medium was prepared and sterilized. De-ionized water was used to prepare the BBM.
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
1) 24 °C ±2°C.
pH:
1)Sample at concentration 0.64 mg/L: pH= 7.9 changed to pH= 7.8 during the test
Control: pH= 8.0 changed to pH= 7.4 during the test
2) 6.7 to 7.4
Nominal and measured concentrations:
1) 0, 0.02, 0.04, 0.08, 0.16, 0.32 and 0.64 mg/L.
2)0.5 mg/l, 1.25mg/l,3.125mg/l, 7.813mg/l, 19.531mg/l and 48.828mg/l

Details on test conditions:
1) TEST SYSTEM
- Test vessel: 50 ml Glass vessel
- Type (delete if not applicable): closed
- Sample volume: 15 ml
- Initial cells density: 5x10(3) cells/ml
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: 6000-8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microscope with counting chamber Cyrus I or electronic particle counter.
- Other: ErC50 was calculated using non-linear regression by the software Prism 4.0

2)Light Quality White Fluoroscent Light
Light Intensity 1500Lux
Photoperiod 16 Hour Light Period : 8 Hour Dark Period
RPM Speed 120 Revolutions per minute
Water Deionized Waer
Test vessel size 100ml
Test solution volume 60ml
Dilution water Bold’s Basal Medium
Test concentration Six test concentration were:
Replicates per concentration
Three replicates for Control
Two replicates for each test concentration
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.13 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 0.11 - 0.15 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.61 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: calculated from equation through probit analysis
Results with reference substance (positive control):
1) Results with reference substance valid
- EC50: 0.75 mg/L
Validity criteria fulfilled:
not specified
Conclusions:
On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach, the 72 hr EC50 value of the test chemical can be expected to be in the range of 0.13 to 0.61 mg/l, respectively. Thus, based on the EC50 value, test chemical can be considered to be toxic to aquatic algae and hence, considered to be classified in 'aquatic acute category 1' as per the CLP classification criteria.
Executive summary:

Data available for the read across chemicals has been reviewed to determine the effect of the test chemical on aquatic algae . The studies are as mentioned below:

Toxicity to aquatic algae study was conducted for 72 hrs for assessing the effect of test chemical on green algae. The test was performed in accordance to OECD Guideline 201 (Alga, Growth Inhibition Test). Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) of strain 86.81 SAG obtained from Institute of botany of the ASCR with an initial biomass conc. 5000 cells /ml was used as a test organism. The stock solution (10 mg/L) was prepared by dissolving yellow powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Test chemical concentrations were not verified analytically. Nominal test chemical conc. used for the study were 0, 0.02, 0.04, 0.08, 0.16, 0.32 and 0.64 mg/l, respectively. Study was performed in a static system for 72 hrs. Desmodesmus subspicatus were exposed to test chemical in 50 ml glass vessel in a volume of 15 ml of liquid solution containing both the chemical and media. Control solution vessel containing OECD medium without the test chemical was also setup during the study. The beakers were placed in a room at a temperature of 23±2°C with a continuous light intensity of 6000-8000 lx, respectively. Alongwith the test chemical, one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. The 24 hr EC50 value of the reference substance was determined to be 0.75 mg/l. Cell counting was carried out using microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0. On the basis of the effect of test chemical on the growth rate of the test organism Desmodesmus subspicatus, the 72 hr median effect concentration (ErC50) value was determined to be 0.13 mg/l (95% CL: 0.11 to 0.15 mg/l). Thus, based on the EC50 value, test chemical can be considered to be toxic to aquatic algae and hence, considered to be classified in 'aquatic acute category 1' as per the CLP classification criteria.

First study was supported by the second study. The effect of test item was studied on the growth of fresh water green algaChlorella vulgaris.The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 0.5mg/l, 1.25mg/l, 3.125mg/l, 7.813mg/l, 19.531mg/l and 48.828mg/l. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be 0.610 mg/L.

On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach, the 72 hr EC50 value of the test chemical  can be expected to be in the range of 0.13 to 0.61 mg/l, respectively. Thus, based on the EC50 value, test chemical can be considered to be toxic to aquatic algae and hence, considered to be classified in 'aquatic acute category 1' as per the CLP classification criteria.

Description of key information

Toxicity to aquatic algae and cyanobacteria:

On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach, the 72 hr EC50 value of the test chemical  can be expected to be in the range of 0.13 to 0.61 mg/l, respectively. Thus, based on the EC50 value, test chemical can be considered to be toxic to aquatic algae and hence, considered to be classified in 'aquatic acute category 1' as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for marine water algae:
0.13 mg/L

Additional information

Toxicity to aquatic algae and cyanobacteria:

Data available for the read across chemicals has been reviewed to determine the effect of the test chemical on aquatic algae . The studies are as mentioned below:

Toxicity to aquatic algae study was conducted for 72 hrs for assessing the effect of test chemical on green algae. The test was performed in accordance to OECD Guideline 201 (Alga, Growth Inhibition Test). Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) of strain 86.81 SAG obtained from Institute of botany of the ASCR with an initial biomass conc. 5000 cells /ml was used as a test organism. The stock solution (10 mg/L) was prepared by dissolving yellow powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Test chemical concentrations were not verified analytically. Nominal test chemical conc. used for the study were 0, 0.02, 0.04, 0.08, 0.16, 0.32 and 0.64 mg/l, respectively. Study was performed in a static system for 72 hrs. Desmodesmus subspicatus were exposed to test chemical in 50 ml glass vessel in a volume of 15 ml of liquid solution containing both the chemical and media. Control solution vessel containing OECD medium without the test chemical was also setup during the study. The beakers were placed in a room at a temperature of 23±2°C with a continuous light intensity of 6000-8000 lx, respectively. Alongwith the test chemical, one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. The 24 hr EC50 value of the reference substance was determined to be 0.75 mg/l. Cell counting was carried out using microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0. On the basis of the effect of test chemical on the growth rate of the test organism Desmodesmus subspicatus, the 72 hr median effect concentration (ErC50) value was determined to be 0.13 mg/l (95% CL: 0.11 to 0.15 mg/l). Thus, based on the EC50 value, test chemical can be considered to be toxic to aquatic algae and hence, considered to be classified in 'aquatic acute category 1' as per the CLP classification criteria.

First study was supported by the second study. The effect of test item was studied on the growth of fresh water green algaChlorella vulgaris.The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 0.5mg/l, 1.25mg/l, 3.125mg/l, 7.813mg/l, 19.531mg/l and 48.828mg/l. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be 0.610 mg/L.

On the basis of the experimental studies of the read across chemical and applying the weight of evidence approach, the 72 hr EC50 value of the test chemical  can be expected to be in the range of 0.13 to 0.61 mg/l, respectively. Thus, based on the EC50 value, test chemical can be considered to be toxic to aquatic algae and hence, considered to be classified in 'aquatic acute category 1' as per the CLP classification criteria.