Methyl (2E)-2-cyano-3-(2,2-difluoro-1,3-benzodioxol-4-yl)prop-2-enoate

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:

other: GLP guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(1984)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

methyl (2E)-2-cyano-3-(2,2-difluoro-1,3-benzodioxol-4-yl)prop-2-enoate

EC Number:

700-526-7

Cas Number:

1333488-95-1

Molecular formula:

C12H7F2NO4

IUPAC Name:

methyl (2E)-2-cyano-3-(2,2-difluoro-1,3-benzodioxol-4-yl)prop-2-enoate

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Composite samples (about 150 ml per concentration and control) of each test concentration were drawn immediately before exposure from appropriate dilution of the stock solution and after 72 hours exposure by mixing identical volumes of the test solutions taken from the approximate Center of the test vessels and kept at - 18°C to - 22°C until analysis.

Test solutions

Details on test solutions:

Stock solutions:
100 mg test substance were mixed with and made up to 1000 ml with test water.

Test concentrations:
Calculated amounts of the stock solution to produce the desired test concentrations were given into the water and were homogeneously distributed. The algae were then transfered into the flasks. The test solution was homogeneously distributed in the test vessels at all test times from 0.02 - 0.07 mg/l. Deposit and small parts of the test substance were swimming at the surface of the test vessels at all test times from 0.4 - 27.1 mg/l.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green Algae (Scenedesmus subspicatus)
- Source (laboratory, culture collection): CIBA-GEIGY Ltd., testing facility

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

21 - 25 °C +/- 1 °C

pH:

7.3 - 7.7

Nominal and measured concentrations:

nominal:
1.23, 3.7, 11.1, 33.3, 100 mg test substance / l

measured:
0.02, 0.07, 0.4, 1.4, 27.1 mg test substance /l

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml Erlenmeyer flasks, on Lab-shaker, 50 ml test solution per flask
- Initial cells density: 4800 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: Continous illumination, cold white fluorescent light, 120 µE/m2 sec +/- 20% (approx. 8000 lux)

Results and discussion

Effect concentrations

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 27.1 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

biomass

Any other information on results incl. tables

Inhibition data

Conc. Actual end [mg/l]	A 1	A 2	A 3	A 4	A 5	A 6	Mean A	Inhibition * IA 0-72h [%]
Blank	377	431	358	448	589	404	434	0.0
0.02	532	440	332				435	0.0
0.07	690	602	749				680	0.0
0.4	661	774	713				716	0.0
1.4	1120	1162	1564				1282	0.0
27.1	1722	1488	1547				1586	0.0

A = Areas under Growth Curves * 10000

* promotion of algal growth compared to control is indicated as 0.0

Analytical determination of test concentrations

Labelling of sample	Nom. Conc. [mg/l]	Conc. Determined [mg/l]	Mean [mg/l]	Percent of nominal conc.
Day 0	Blank	n.d. / n.d.	-	-
Day 0	1.23	0.06 / 0.08	0.07	5.7
Day 0	3.7	0.5 / 0.6	0.6	15.1
Day 0	11.1	3.4 /3.7	3.6	32.4
Day 0	33.3	7.6 / 8.1	7.9	23.7
Day 0	100	33.8 /49.1	41.5	41.5
Day 3	Blank	n.d. / n.d.	-	-
Day 3	1.23	0.01 / 0.02	0.02	1.6
Day 3	3.7	0.05 / 0.08	0.07	1.9
Day 3	11.1	0.6 / 0.2	0.4	3.6
Day 3	33.3	1.2 / 1.6	1.4	4.2
Day 3	100	30.1 / 24.1	27.1	27.1

n.d. = not detectable (<0.01 mg/l)

Becauee of the poor water solubility of the test substance the recoveries at start of exposure range from 5.7 t o 41.5%. A lose of test substance appeared between the highest and the lowest test concentration due to the heterogenous stock solution containing non-dissolved particles.Atthe end of exposure setteled down particles are at the origin of the 4.1 to28.8%lower recoveries.