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Ecotoxicological information

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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
For the determination of the growth curve not the cell amount was used, but the fluorescence. In a pre-test the correlation of cell amount and fluorescence was confirmed.
GLP compliance:
no
Remarks:
accredited by DAkkS

Test material

Constituent 1
Chemical structure
Reference substance name:
p-benzoquinone
EC Number:
203-405-2
EC Name:
p-benzoquinone
Cas Number:
106-51-4
Molecular formula:
C6H4O2
IUPAC Name:
1,4-benzoquinone
Test material form:
solid: particulate/powder

Sampling and analysis

Analytical monitoring:
no
Details on sampling:
A stock solution was prepared with the test item. Different dilutions with ultrapure water were prepared thereof.
50 mL-test preparations contained 40 ml of the related dilution as well as 5 ml algal medium and 5 ml algal culture (consisting of algal medium and Desmodesmus subspicatus CHODAT). The tests were performed in duplicate over a 72 h period of time.

Test solutions

Vehicle:
not specified

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

Test temperature:
20 – 22 °C
pH:
8.1 - 9.1
Nominal and measured concentrations:
0,5 mg/l, 1,0 mg/l, 2,0 mg/l, 3,0 mg/l, 10 mg/l
Details on test conditions:
In pre-tests it was found out that a direct correlation of growth rate and measurable fluorescence exists. Hence, the measurement of the fluorescence of all samples was performed using a fluorescence measuring device (Kontron) after 0, 24, 48 and 72 h.
Reference substance (positive control):
yes
Remarks:
K2Cr2O7

Results and discussion

Effect concentrations
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: fluorescence

Any other information on results incl. tables

Table 2: Fluorescence of all test samples with p-benzoquinone und control (=0 mg/l)

concentration [mg/l]

fluorescence

0 h

24 h

48 h

72 h

I

II

mean

I

II

mean

I

II

mean

I

II

mean

0

2,6

2,5

2,55

3,4

3,2

3,3

6,0

5,1

5,55

9,6

9,3

9,45

0,5

2,5

2,8

2,65

2,0

1,8

1,9

5,1

4,6

4,90

6,7

7,0

6,90

1

2,8

3,0

2,90

3,1

3,2

3,2

3,9

4,3

4,10

6,1

7,3

6,70

2

2,8

2,7

2,75

2,5

2,9

2,7

3,3

3,8

3,60

5,6

5,5

5,60

3

2,4

2,6

2,50

2,4

2,6

2,5

3,0

2,9

3,00

4,1

4,2

4,20

10

2,0

2,5

2,25

1,7

1,7

1,7

1,2

1,3

1,30

1,4

1,4

1,40

 

Table 3: growth rate of Desmodesmus subspicatus CHODAT at different concentrations of p-benzoquinone in relation to control (= 100%)

concentration [mg/l]

growth rate in 72 h of

Desmodesmus subspicatus in %

0,5

80,48

1

57,77

2

46,37

3

26,85

10

0,00

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The toxicity of p-benzoquinone to algae was investigated in a study acc. to OECD Guideline 201 (Alga, Growth Inhibition Test). The 72 h EC50 was determined to be 1,5 mg/L (based on recalculated initial concentrations).
Executive summary:

The toxicity of p-benzoquinone to algae was investigated in a study acc. to OECD Guideline 201 (Alga, Growth Inhibition Test).

For the hazard and risk assessment the effect concentration for growth rate should be used: EC50 (72 h) = 1,5 mg/L.