O,O,O-triphenyl phosphorothioate

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:

2002-05-13 to 2002-06-21

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)

Version / remarks:

adopted on April 1984

Deviations:

yes

Remarks:

, no analytical dose verification.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Due to the low water solubility of the test item, a supersaturated dispersion with a loading rate of 100 mg/L was prepared by weighing 30 mg of the test item into 300 mL test water. No auxiliary solvent or emulsifier was used. The test item was mixed into the test water as homogeneously as possible by ultrasonic treatment for 15 minutes and by intense stirring for 96 hours at room temperature to dissolve a maximum concentration of the test item in the dispersion. Then the supersaturated dispersion of the test item was filtered through a membrane fiber (Schleicher & Schuell, Type NC45, pore size 0.45 µm) just before the start of the test
- Controls: Blank: water.
- Stock solution: Due to the low water solubility of the test item, a supersaturated dispersion with a loading rate of 100 mg/L was prepared by weighing 30 mg of the test item into 300 mL test water.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): none reported

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water Flea
- Strain: Daphnia magna Straus
- Source: RCC Ltd., Itingen, Switzerland
- Age at study initiation (mean and range, SD): 6-24 h
- Method of breeding: under conditions identical to those of the tests
- Pretreatment: At the start of the test, the used daphnids were 6 - 24 h old and were not first brood progeny
- Feeding during test: none

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

250 mg CaCO3/L

Test temperature:

20 °C

pH:

7.8 - 8.0

Dissolved oxygen:

8.7 - 9.0 mg/L

Nominal and measured concentrations:

Nominal loading rate: 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL glass beakers covered with glass plates filled with 50 mL solution per beaker
- Aeration: None during the test. The water was aerated with clean air for at least 24h before use.
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- Biomass loading rate: < 1 daphnia per 2 mL of test solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water according to the guideline.
- Intervals of water quality measurement: oxygen, pH, temperature daily

OTHER TEST CONDITIONS
- Photoperiod: Fluorescent light, 16 hours daily with a 30 minute transition period
- Light intensity: approx. 550 - 685 lux

EFFECT PARAMETERS MEASURED: Immobilization

Reference substance (positive control):

yes

Remarks:

Potassium dichromate, tested at least once a year to demonstrate satisfactory test conditions.

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Remarks:

100 mg/L loading rate WAF

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Remarks:

100 mg/L loading rate WAF

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Remarks:

100 mg/L loading rate WAF

Basis for effect:

mobility

Details on results:

- Effect concentrations exceeding solubility of substance in test medium: yes. No effects were observed at a loading rate of 100 mg/L which exceeds the solubility of the test substance. It can be concluded that the test substances causes no toxic effects in the range of solubility.
- Mortality of control: 0 % mortality was observed in the control.

Validity criteria fulfilled:

yes

Conclusions:

The test substance is not acutely harmful to aquatic invertebrates up to the limit of solubility in water.

Description of key information

The test substance is not acutely harmful to aquatic invertebrates up to the limit of solubility in water.

Additional information

Three studies investigating the short-term toxicity of O,O,O-triphenyl phosphorothioate to aquatic invertebrates are available.

The key study was performed according to GLP and OECD guideline 202 using Daphnia magna as test organism (RCC 2002). Daphnids were exposed to control and saturation concentration (undiluted filtrate of the test item with a nominal loading rate of 100mg/L) for 48h.  Mortality/immobilization and sublethal effects were observed daily. No effects were observed at saturation concentration (undiluted filtrate of the test item with a nominal loading rate of 100mg/L). Thus, the 48h-EL50 was determined to be higher than saturation concentration. It can be concluded that the test substance causes no toxic effects in the range of solubility. 

In a supporting study conducted according to OECD guideline 202 (Ciba-Geigy 1996) with O,O,O-triphenyl phosphorothioate in a lower purity (purity > 25%) the 48h-EL50 based on mobility of the test animals was higher than the saturation concentration (100 mg/L loading rate WAF).

In addition, a non-GLP study on acute toxicity to Daphnia is available (Ciba-Geigy 1988). The acute toxicity of the test item to Daphnia magna was studied under static conditions over an exposure time of 24h. Daphnids were exposed to control, solvent control, and test item at nominal concentration of 10, 18, 32, 58 and 100 mg/L for 24 hr.  Mortality/immobilization and sublethal effects were recorded daily.  The EC50 was determined to be 49 mg/L, and thus above the solubility limit. Undissolved test material was observed from the beginning of the test. Therefore, this study is disregarded due to major methodological deficiencies and insufficient exposure duration.

Based on the available data, it can be concluded that O,O,O- triphenyl thiophosphate is not acutely toxic to aquatic invertebrates up to the limit of solubility in water.