Sodium O,O-diisobutyl dithiophosphate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

Please refer to Read Across Statement attached in Section 13

Reason / purpose for cross-reference:

read-across source

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1 026 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 800 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

1 800 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 1.7 mg/l which is not considered significantly different from the results obtained in an international ring test (EC50 = 1.0 - 2.2mg/l)

Validity criteria fulfilled:

yes

Remarks:

Cell density increased by a factor of more than 16 during test, variation in pH < 1, results for reference substance within acceptable range, 1.7 (1.0-2.2) mg/L

Conclusions:

EC50(72 h) for the test substance is >1800 mg/L for Skeletonema costatum

Executive summary:

The test was performed according to the ISO 10253 under GLP compliance. Skeletonema costatum was exposed to the test item for 72 hours. EC50(72 h) for the test substance is >1800 mg/L

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08.10.2012 - 19.12.2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)

GLP compliance:

yes (incl. QA statement)

Remarks:

(Not the chemical analyses)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: (Nominal) 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L
- Sampling method: Samples were collected at test start, every 24 hours and at the end of the test for chemical analysis of the test product. Duplicate samples of 15 mL were collected in 20-mL plastic vials for later analysis. Only one of these samples were analysed. The spare samples were discarded after sponsor approved the report.
- Sample storage conditions before analysis: at - 20 ˚C ± 2.0˚C

Vehicle:

no

Details on test solutions:

A stock solution of 2,400 mg/L was prepared by weighing out 2,400 mg of the test product and dissolving it in 1 L of algal test medium. pH in the stock solutions was 9.3 and was therefore adjusted to 8.2 by adding 4 droplets of 1 M HCl. The test solutions were prepared by diluting the appropriate amounts of stock solution in algal test medium.
The test product was tested at the following nominal concentrations: 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
Clone: NIVA, CHL 1
The alga Pseudokirchnerella subcapitata is cultured at DHI under the test conditions prior to the start of the test. 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 ± 0.0˚C

pH:

8.0-8.1 at the beginning and 7.8-10.2 at the termination of the test.

Nominal and measured concentrations:

The results from the analysis showed a measured IBP1-Na concentration of 88-102% of the estimated nominal concentration of IBP1-Na. As the tested concentraions were maintained within ± 20% of the nominal concentrations, the statistical calculaiton were based on the nominal concentrations.

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 250 mL glass flasks with wide neck, containing 100 mL of test solution

- Renewal rate of test solution (frequency/flow rate):
- Initial cells density:
- Control end cells density:
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 3
- No. of vessels 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
- Adjustment of pH: Test media: from 9.3 to 8.2 by adding 1 M HCl
- Photoperiod: 72 hours
- Light intensity and quality: fluorescent light with an intensity of approx 60-120 μmol x m-2 x sec-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Beckman Coulter Multisizer and in-vivo fluorescence, Turner TD-700 Laboratory Fluorometer

TEST CONCENTRATIONS
- Test concentrations (nominal): 0 (control); 20; 50; 100; 200; 500; 1,000 and 2,000 mg/L.

Reference substance (positive control):

yes

Remarks:

K2Cr2O7, CAS no 7778-50-9

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

261 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: 245-278

Details on results:

- Exponential growth in the control (for algal test): yes

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: 1.09 mg/L

Validity criteria fulfilled:

yes

Remarks:

Growth rate = 1.9/day (> 1.4/day). Variation coefficient of control growth rates = 1.4 (< 5%). Mean varion coefficen = 13.4% (<35%). Increase of pH > 1.5 unit from start to end for control, not considered significant. EC50 for ref. sub. = 1.09 (0.65-1.73)

Conclusions:

ErC50(72h) of test item is 261 mg/L for Pseudokirchneriella subcapitata.
Remark: the test solution contains NaOH due to the production method.

Executive summary:

The toxicity to aquatic algae and cyanobacteria test was performed according to OECD Guideline 201 and ISO 8692 under GLP compliance. Pseudokirchneriella subcapitata, algae was exposed to the test item for 72 hours. ErC50(72h) of the test item value is determinded 261 mg/L.

Description of key information

OECD 201, freshwater: ErC50(72h) of the test item value is determinded 261mg/L

Read-across, OECD 201, marine water: ErC50(72h) of the test item value is determinded 261mg/L, ErC10(72h) is determined 1026 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

261 mg/L

EC50 for marine water algae:

1 800 mg/L

EC10 or NOEC for marine water algae:

1 026 mg/L