m-tolyl isocyanate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

other information

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

72 h EC₁₀ (growth rate) = 24.8 mg/L; 72 h EC₅₀ (growth rate) = 53.11 mg/L (MITI, 1994)

Key value for chemical safety assessment

EC50 for freshwater algae:

17.4 mg/L

EC10 or NOEC for freshwater algae:

6.8 mg/L

Additional information

Due to rapid hydrolysis of isocynantes, the inhibitory effects of the primary amine transformation product of m-tolyl isocyanate, m-toluidine, is presented as the most relevant endpoint for use in the CSA.

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 determined 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.