Phenol, 2,4-dinitro-, sulfurized, leuco derivatives

Toxicity to aquatic algae and cyanobacteria

Administrative data

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:

other: Study performed according to OECD-Guideline and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Principles of method if other than guideline:

Method was modified to differentiate between a reduced growth of algae due to real toxic effects of the test substance or due to an indirect effect, a reduced algae growth by light absoprtion in coloured test solutions.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

see confidential details on test material

IUPAC Name:

see confidential details on test material

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

pH:

At the start of the tests, the pH ranged from 8.1 to 9.5.
At the end of the tests, the pH ranged from 8.1 to 8.9.

Nominal and measured concentrations:

200 mg DIRESUL BLACK RDT LlQUlD were dissolved in test medium and filled to a volume of 200 ml. From this stock solution further dilutions in test medium were prepared and the respective amount of algae added. The final nominal test concentrations were: 50, 5, 1, 0.5, 0.1 and 0.01 mg/l.
DIRESUL BLACK RDT LIQUID was found to be stable under the test conditions. The concentration in all tests ranged from 85.5 % to 107.7 % of the nominal concentration.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

5.99 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Experimental Part B

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.84 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Experimental Part A

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

54.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Experimental Part A

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

8.59 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Experimental Part B

Effect concentrations 5

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 - 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Experimental Part B

Effect concentrations 6

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

ca. 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Experimental Part B

Effect concentrations 7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Experimental Part A

Effect concentrations 8

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

1 - 5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Experimental Part A

Details on results:

The test included two experimental parts:
Experimental part A: the algae grew in test medium with dissolved dyestuff in Erlenmeyer flasks.
Experimental part B: the algae grew in separate containers (test tube) which were surrounded by the black coloured solutions of the same concentration as tested in part A.

Applicant's summary and conclusion

Conclusions:

The growth inhibition of Scenedesmus subspicatus was in the same magnitude when the algae grew in test medium without test substance but under reduced light intensities by the filter effect (experimental part B) as in experimental part A, where the algae grew in test solutions without dissolved test substance. In conclusion, this modified algae test clearly demonstrated that the observed inhibition effect of the substance was caused only by the indirect effect, the light absorption in the coloured test solutions. Thus, a toxic effect of the test substance on the algae cells can be excluded up to a concentration of 50 mg/l.

Executive summary:

The influence of DIRESUL BLACK RDT LIQUID on the growth of the green algae Scenedesmus subspicatus was investigated. The study was performed according to the EEC Directive 92/69. The test method was modified to differentiate between a reduced growth of algae due to real toxic effects of the test substance on the algae cells or due to an indirect effect, a reduced algae growth by light absorption in coloured test solutions.

The test included two experimental parts: Experimental part A: the algae grew in test medium with dissolved dyestuff in Erlenmeyer flasks. Experimental part B: the algae grew in separate containers (test tube) which were surrounded by the black coloured solutions of the same concentration as tested in part A.

The biological results of both experimental parts A and B were almost identical. This was shown by several calculated parameters, the NOEC, LOEC and the EC 50 values:

In part A the NOEC was 1.0 mg/l, and in part B the NOEC was found to be between 1 and 5 mg/l. The LOEC was found to be between 1 and 5 mg/l in part A and it was about 5 mg/l in part B.

The percentage inhibition of algae biomass and the algae growth rate (IJ) after 72 hours of exposure were in the same order of magnitude. The EC 50 values calculated for both growth parameters, showed no significant differences.

Experimental Part A       EbC 50:       1.84 mg/l       Er C 50:       54.1 mg/l

Experimental Part B                           5.99 mg/l                          8.59 mg/l

Thus, the growth inhibition of Scenedesmus subspicatus was in the same magnitude when the algae grew in test medium without test substance but under reduced light intensities by the filter effect (experimental part B) as in experimental part A, where the algae grew in test solutions without dissolved test substance. In conclusion, this modified algae test clearly demonstrated that the observed inhibition effect of the substance was caused only by the indirect effect, the light absorption in the coloured test solutions. Thus, a toxic effect of the test substance on the algae cells can be excluded up to a concentration of 50 mg/l.