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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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Reliable source, basic data given.
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(1984)
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
Stock solutions preparation: DMSO was used as a solvent (Final concentration: 6.12-648 mg/L)
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
ATC 22662
Test type:
other: static, closed system
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
23-25°C
Nominal and measured concentrations:
6.8, 12.4, 22.2, 40 and 72 mg/L nominal
Details on test conditions:
-Growth/test medium: OECD medium
-Shaking: Occasional shaking
-Exposure vessel type: 100 mL-medium in a 300 mL-Erlenmeyer flask with a silicon cap which allow ventilation
-light levels and quality during exposure: 4000-7000 Lux, continuous
-Number of replicates: 3 parallel runs for each concentration
-initial cell number: 1.0*10000 cells/mL
-Controls with and without vehicle were taken for test
Reference substance (positive control):
not required
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
< 6.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
17.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
24.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 0.07 - 37.56
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
53.11 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 30.97 - 142.66
Details on results:
In the report of the reference the toxicity of m-Toluidine to algae was calculated on the basis of bio mass. According to the Guidance on information requirements and chemical safety assessment R.7b (ECHA, 2012) results based on the biomass should not be used for assessment since biomass results depend on the growth rate of the species as well as the test duration and other elements of the test design. Therefore the toxicity was recalculated based on growth rate with cell concentrations given in the report.
The growth rate was calculated based on the cell concentration of each exposure using ToxRatPro Version 2.10.
Reported statistics and error estimates:
statistical method: probit method

 m-Toluidine          Cell concentration of each exposure (1000 cells/mL) 
 concentration (mg/L)  0 hour  24 hour  48 hour  72 hour
 0 1.2  3.8   34.0  98.4
 6.8  1.2  3.7  22.8  69.2
 12.4  1.2  5.0  19.3  59.7
 22.2  1.2  3.3  14.5  58.5
 40  1.2  3.0  12.8  31.0
 72  1.2  3.0  4.5  4.0

Growth curves: Logarithmic growth until end of the test

Validity criteria fulfilled:
not specified
Remarks:
The cell density in the control cultures increased by a factor of at least 16 within 72 h. Since means of three treatments had been under analysis, the validity criterion concerning the CV of the section-by-section growth rate could not be evaluated.
Conclusions:
For m-toluidine on the green algae Selenastrum capricornutum a 72h-EC10 of 24.8 mg/L and a 72h-EC50 of 53.11 mg/L were obtained based on growth rate.
Executive summary:

Following the OECD Guideline 201 (Alga, Growth Inhibition Test) a 72h-EC10 of 24.8 mg/L and a 72h-EC50 of 53.11 mg/L was received on Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata). The values are based on nominal concentration as no analytical monitoring was performed.

In the report of the study conducted by EA, Japan: "Investigation of the Ecotoxicological Effects of OECD High Production Volume Chemicals", Office of Health Studies, Environmental Health Department, Environment Agency, Japan

the toxicity of m-toluidine to algae was calculated on the basis of bio mass. These values based on biomass are also reported in the OECD SIDS document. According to the Guidance on information requirements and chemical safety assessment R.7b (ECHA, 2012) results based on biomass should not be used for assessment since biomass results depend on the growth rate of the species as well as the test duration and other elements of the test design. Therefore the toxicity was recalculated based on growth rate with cell concentrations given in the report.

The test was carried out in triplicate for each nominal concentration. DMSO was used as vehicle. According to the OECD Guideline 201, if organic solvents are used, the concentration should not exceed 100 mg/L and require the perfomance of additional solvent controls. In this study the solvent is present in concentrations up to 648 mg/L. Controls with and without vehicle were taken for test. As the control response was satisfactory with a 82 times cell increase after 72 h, the present study was scored as reliable although the solvent content was high.

Although the study cannot be fully validated it is scored as reliable based on the data given.

Description of key information

For m-toluidine on the green algae Selenastrum capricornutum a 72h-EC10 of 24.8 mg/L and a 72h-EC50 of 53.11 mg/L were obtained based on growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:
53.11 mg/L
EC10 or NOEC for freshwater algae:
24.8 mg/L

Additional information

m-Toluidine was assessed within the scope of the ICCA/HPV-program, and the test on toxicity to aquatic algae conducted by the Chemicals Inspection and Testing Institute, Japan was recalculated as the presented results relate to the area under growth curve, i.e. biomass. According to the Guidance on information requirements and chemical safety assessment R.7b (ECHA, 2012) results based on the biomass should not be used for assessment since biomass results depend on the growth rate of the species as well as the test duration and other elements of the test design. Thus, the presented result was recalculated to obtain results relating to growth rate.

Following the OECD Guideline 201 (Alga, Growth Inhibition Test) a 72h-EC10 of 24.8 mg/L and a 72h-EC50 of 53.11 mg/L was received on Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata).

The test was carried out in triplicate for each nominal concentration. No analytical monitoring was performed. DMSO was used as vehicle. Controls with and without vehicle were conducted. The cell density increased 82 times after 72 hours compared to the density at the start of the test. Although the study cannot be fully validated the present study was scored to be reliable based on the data given.

According to the German standard method (Scenedesmus cell multiplication inhibition test) (L9) an effect concentration of the beginning growth inhibition (EC3) of 10 mg/L was received by Bringmann (1959). According to the Guidance on information requirements and chemical safety assessment R.7b (ECHA, 2012) results based on the biomass should not be used for assessment since biomass results depend on the growth rate of the species as well as the test duration and other elements of the test design. Furthermore, the author does not give any information concerning the monotone exponential growth of the control samples. Thus, the presented result was scored as not reliable. With the same argument the study of Maas-Diepeveen (1986), as basing on yield, was scored to be not reliable. Additionally, other studies were presented which were scored as not reliable due to an unsuitable test system or significant methodological deficiencies.