p-benzoquinone

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

Test material information

Constituent 1

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.