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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Objective of this study was to observe the action of test chemical 1,4-dichloro-2-nitrobenzene when it exposed with the Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test).
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The stock solution 100 mg/l was prepared by dissolving white powder in OECD growth medium. Test solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
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

ACCLIMATION - No data available
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
23±2°C
pH:
Test at highest concentration 22.5 mg/l: pH 7.6 changes to 8 during test
Control: 8.1 changes to 8.8 during test
Nominal and measured concentrations:
0, 4.5, 6.7, 10, 15 and 22.5 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 ml Glass vessel
- Type (delete if not applicable): closed (with air permeable stopper)
- 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
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
12.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CI was 10.9 to 15 mg/l
Results with reference substance (positive control):
- Results with reference substance valid
- EC50: 0.75 mg/L (24 hours)
Reported statistics and error estimates:
ErC50 was calculated using non linear regression by the software Prism 4.0
Validity criteria fulfilled:
yes
Conclusions:
Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 12.8 mg/l.
Executive summary:

Objective of this study was to observe the action of test chemical 1,4-dichloro-2-nitrobenzene when it exposed with the Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 100 mg/l was prepared by dissolving white powder in OECD growth medium. Test solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 0, 4.5, 6.7, 10, 15 and 22.5 mg/l concentrations were used.

With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs.

Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 12.8 mg/l. Based on the ErC50 value, substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP classification criteria.

Description of key information

Objective of this study was to observe the action of test chemical 1,4-dichloro-2-nitrobenzene when it exposed with the Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 100 mg/l was prepared by dissolving white powder in OECD growth medium. Test solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 0, 4.5, 6.7, 10, 15 and 22.5 mg/l concentrations were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 12.8 mg/l. Based on the ErC50 value, substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP classification criteria.

 

Key value for chemical safety assessment

EC50 for freshwater algae:
12.8 mg/L

Additional information

Summarized studies result of the toxicity of test chemical on the growth of algae were observed and mention below:

Objective of this study was to observe the action of test chemical 1,4-dichloro-2-nitrobenzene when it exposed with the Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 100 mg/l was prepared by dissolving white powder in OECD growth medium. Test solution was kept in ultrasonic bath for 20 min. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 0, 4.5, 6.7, 10, 15 and 22.5 mg/l concentrations were used. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the ErC50 was determine to be 12.8 mg/l. Based on the ErC50 value, substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP classification criteria.

 

Above study was supported by the secondary source. The green alga C. pyrenoidosa was exposed to the test compound 1,4-dichloro-2- nitrobenzene during a 96 hrs study. The EC50 is determine to be 2100 µg/L (1500-2800 µg/L) i.e. 2.1 mg/L (1.5- 2.8 mg/L). Thus on the basis of effects observed on algae, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

Similar 72 hrs short term toxicity to microalga Selenastrum capricornutum ATCC 22662 was performed to evaluate the toxic nature of the test compound Benzene, 1, 4-Dichloro-2-Nitro. Stock solution was prepared with DMSO (1000 mg/L). Controls with and without this vehicle were taken for the test. The EC50 and the NOEC for the test compound Benzene, 1, 4-Dichloro-2-Nitro in Selenastrum capricornutum ATCC 22662 is 5.0 mg/L and 2.0 mg/L respectively. Based on the EC50, chemical consider to be toxic and classified as aquatic chronic 2 as per the CLP classification criteria.

 

As the experimental key study conducted according to the guideline, thus on the basis of above study, chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria.