O,O-bis(methylphenyl) hydrogen dithiophosphate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

FEB 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Qualifier:

according to guideline

Guideline:

ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))

GLP compliance:

yes

Remarks:

Chemical analysis was not performed according to GLP

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples from the test concentrations 2-100 mg/L were analysed as they covered the concentrations causing 0-100 % effect.
- Sampling method: In order to verify the tested concentrations, samples were collected from the test solutions at the initiation of the test (t= 0 h) and at the termination of the test (t= 48 h).
- Sample storage conditions before analysis: Samples were stored at -20 ± 2.0 °C until analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution of 100 mg/L were prepared by weighing out 100.1 mg of the test material and dissolving it in 1 L test medium. pH were adjusted to 8.0 in the stock solution. The test solutions were prepared by diluting the appropriate amounts of stock solution in the test medium.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Strain/clone: A strain of freshwater crustacean Daphnia magna Straus (Cladocera, Crustacea)
- age: less that 24 hours old
- Source: originally isolated from Langedam (Birkerød, Denmark), cultured at DHI since 1979.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test temperature:

20.1 ± 0.1 °C

pH:

7.8-8.3

Dissolved oxygen:

96-100 % saturation

Nominal and measured concentrations:

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

The chemical analysis showed a measured Cresyl-P1 concentration of 113-116 % of the estimated nominal concentration. As the tested concentrations were maintained within ± 20 % of the nominal concentrations, the statistical calculation was made on the basis of the nominal concentrations.

Details on test conditions:

TEST SYSTEM:
Static test in 50 mL glass beakers with 25 mL of test solution
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 6

Reference substance (positive control):

yes

Remarks:

24-h acute toxicity test on the reference substance potassium dichromate (CAS No. 7778-50-9) was performed to check the sensitity of the test animals.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

19 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 8.9-47 mg/L (95% confidence interval)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

29 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 14-74 mg/L (95% confidence interval)

Results with reference substance (positive control):

24-h EC50 = 1.6 (1.4-1.7) mg/L, which is witin the range specified in the ISO 6341 guideline (0.6-2.1 mg/L).

Validity criteria fulfilled:

yes

Remarks:

< 10 % of control animals were immobilized. Dissolved oxygen saturation at the end was ≥ 96% in both tests and controls. EC50(24h) = 1.6 mg/L for control substance (K2Cr2O7, CAS no 7778-50-9) which in the specified range (0.6-2.1 mg/L)

Conclusions:

The 48-hour EC50 was calculated to be 19 mg/L (nominal).

Executive summary:

An acute toxicity test with the crustacean Daphnia magna was conducted according to OECD Guideline 202 under GLP compliance. After 48 hour exposure the immobility was recorded. The 48 h EC50 for test item was observed to be 19 mg/L (nominal).

Description of key information

An acute toxicity test with the crustacean Daphnia magna was conducted according to OECD Guideline 202 under GLP compliance. After 48 hour exposure the immobility was recorded. The 48 h EC50 for test item was observed to be 19 mg/L (nominal).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

19 mg/L