O,O,O-tris(2(or 4)-C9-10-isoalkylphenyl) phosphorothioate

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: GLP guideline study with analytical monitoring

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(91/69/EEC C.3)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

O,O,O-tris(2(or 4)-C9-10-isoalkylphenyl) phosphorothioate

EC Number:

406-940-1

EC Name:

O,O,O-tris(2(or 4)-C9-10-isoalkylphenyl) phosphorothioate

Cas Number:

126019-82-7

Molecular formula:

C45 H69 O3 P S

IUPAC Name:

O-2-(2-methylnonyl)phenyl O-4-(2-methylnonyl)phenyl O-2-(2-methyloctyl)phenyl phosphorothioate

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

For the analysis of the actual test item concentrations the following samples were taken:

Just before the start of the test:
- duplicate samples from each test medium (without algae)
- duplicate samples from the control (without algae)

After 72 hours:
- duplicate samples from each test medium (without algae)
- duplicate samples from the control (without algae)

For the 72-hour stability samples additional flasks with adequate volumes of the freshly prepared test media of all test concentrations and the control were incubated under the same conditions as in the actual test but without algae. All samples were analyzed immediately after sampling. The concentrations of the test item were analyzed in all test medium samples from both sampling times (0 and 72 hours). From the control samples only
one of the duplicate samples was analyzed from each of both sampling times.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Five WAFs (Water Accommodated Fractions) were prepared. Four days prior to the start of the test, five individual mixtures with loading rates of 4.6, 10, 22, 46 and 100 mg/L were prepared by weighing 11.9, 10.7, 15.5, 32.9, and 70 mg of test item into 2.5, 1.0, 0.70, 0.70, and 0.70 liter test water, respectively. No auxiliary solvent or emulsifier was used. The test item was mixed into the test water as homogeneously as possible by an ultrasonic treatment for 15 minutes and intense stirring for 96 hours on a magnetic stirrer at room temperature in the dark. The long stirring period of 96 hours was chosen to dissolve a maximum concentration of the test item in test water. The results of a pre-test (without GLP) have shown that during this time no significant loss of the test item was to be expected. These saturated aqueous dispersions were filtered through a membrane filter (Schleicher & Schuell, Type NC20, pore size 0.2 µm) just before the start of the test. With reduced negative pressure the dispersions were filtered as carefully as possible to avoid, that the liquid test item was sucked through the filter. The filtrates of the dispersions with dissolved test item were tested on algae as WAFs. Additionally, a control was tested in parallel.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: No. 86.81 SAG
- Source: Sammlung von Algenkulturen Göttingen (SAG, Experimentelle Phykologie und Sammlung von Algenkulturen, Albrecht-von-Haller-lnstitut für Pflanzenwissenschaften, Universität Göttingen, D-37073 Göttingen, Germany)
- Method of cultivation: according to test guidelines

ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions: Same conditions as test

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

24 mg/L as CaCO3

Test temperature:

22-23 °C

pH:

7.9 - 8.1

Nominal and measured concentrations:

Nominal (loading rate): 4.6, 10, 22, 46, 100 mg/L
Mean measured concentrations:

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL Erlenmeyer flasks covered with glass dishes
- Aeration: None
- Initial cells density: 10000 cells/mL
- Control end cells density: 62.28 x 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: According to guideline
- Culture medium different from test medium: No
- Intervals of water quality measurement: Daily

OTHER TEST CONDITIONS
- Photoperiod: Continuously illumination
- Light intensity and quality: 9200 lux (mean value)

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Electronic particle counter (Coulter Counter, Model ZM)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 2.2

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Remarks on result:

other: Value based on loading rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks on result:

other: Value based on loading rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Remarks on result:

other: Value based on loading rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks on result:

other: Value based on loading rate

Details on results:

- Exponential growth in the control: yes
- Any stimulation of growth found in any treatment: No
- Effect concentrations exceeding solubility of substance in test medium: Yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes