O,O-bis(methylphenyl) hydrogen dithiophosphate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

DEC 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

other: EN ISO 8692:2012: "Water quality - fresh water algal growth inhibition test with unicellular green algae"

Version / remarks:

Third edition, 2012.02.15

GLP compliance:

yes

Remarks:

Chemical analysis was not conducted according to GLP.

Analytical monitoring:

yes

Details on sampling:

- Sampling method: In order to verify the actual test concentrations, duplicate samples of each test concentration were taken at the initiation of the test, every 24 hours and at the termination of the test.
- Sample storage conditions before analysis: The samples were stored at -20°C ± 2.0°C until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test solutions were prepared by diluting the stock solution in the algal test medium.
- Eluate: A stock solution was prepared by weighing out 125.1 mg of the test item and dissolving it in 1,000 mL of algal test medium. pH was adjusted to 8.1.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Pseudokirchnerella subcapitata (clone: NIVA, CHL 1) is cultured at DHI. Algae from this culture were used in the study.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23.2°C

pH:

7.8-9.8

Nominal and measured concentrations:

Nominal concentrations: 0 (control); 1.0; 2.0; 5.0; 10; 20; 50 and 100 mg/L (based on test material).

The results from the Cresyl-P1 analysis of the nominal test concentrations 5.0-100 mg/L showed a measured Cresyl-P1 concentration of 113-118% of the estimated nominal concentration of Cresyl-P1. As the test concentrations were maintained within ±20% of the nominal concentrations, the statistical calculation was based on nominal concentrations.

Details on test conditions:

TEST SYSTEM
250 mL glass flasks with wide neck, containing 100 mL of test solution
- No. of flasks per concentration (replicates): 3
- No. of flasks per control (replicates): 6 (flasks with algae but no test product) + a blank of each concentration (flasks with the test product but no algae)
Furthermore, one flask of the control and one flask of each test concentration without algae were used to cellect samples for chemical analysis.

OTHER TEST CONDITIONS
- Photoperiod: 72 hours
- Light intensity and quality: fluorescent light with an intensity of approx 60-120 μmol x m-2 x sec-1

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

8.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: 8.0-9.9 mg/L (95% confidence interval)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

13.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 12.5-15.5 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.2 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Yield

Remarks on result:

other: 1.8-2.6 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 2.8-4.1 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

1.9 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: 1.5-2.2 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.83 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: 0.59-1.0 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.64 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

0.83 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Yield

Remarks on result:

other: 0.57-1.0 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 0.64 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.64 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

2.9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 2.3-3.5 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.93-1.6 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

1.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Remarks on result:

other: 0.89-1.6 mg/L (95% confidence interval)

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Yield

Results with reference substance (positive control):

The sensitivity fo the algae was verified. The EC50 value of 1.09 (1.06-1.11) mg/L for potassium chromate showed that the sensitivity of the algae was within the accepted range.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (growth rate) was found to be 8.9 mg/L for test item.

Executive summary:

An algae growth inhibition test with Pseudokirchneriella subcapitata was conducted according to OECD Guideline 201 under GLP compliance. After 72 hour exposure the growth rate was recorded. The 72 h EC50 (growth rate) was calculated to be 8.9 mg/L for test item.

Description of key information

An algae growth inhibition test with Pseudokirchneriella subcapitata was conducted according to OECD Guideline 201 under GLP compliance. After 72 hour exposure the growth rate was recorded. The 72 h EC50 (growth rate) was calculated to be 8.9 mg/L for test item.

Key value for chemical safety assessment

EC50 for freshwater algae:

8.9 mg/L

EC10 or NOEC for freshwater algae:

0.83 mg/L