Bis[O,O-bis(2-ethylhexyl) dithiophosphorato-S,S']dioxodi-μ-thioxodimolybdenum

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Single samples for analysis were taken from the undiluted saturated solution (SS) and the control.
Frequency: at t=0 h and t=96 h
Volume: 5.0 mL
Storage: Not applicable, samples were analysed on the day of sampling

Vehicle:

no

Details on test solutions:

The test item was not completely soluble at the loading rate initially prepared. Thus, preparation of test solutions started with a loading rate of 100 mg/L applying a three-day period of magnetic stirring to reach the maximum dissolution of the test item in medium. The resulting aqueous mixture was allowed to settle for 1 hour and thereafter the Saturated Solution (SS) was collected by means of siphoning. The SS was used as the highest test concentration. The test solution was clear and colorless at the end of the preparation procedure. No correction was made for the purity/composition of the test item.
The method of preparation of the test medium was based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000.
- Controls: Test medium without test item or other additives

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM
- Common name: carp
- Source: Zodiac, proefacc, "De Haar Vissen", Wageningen University and Research Centre, The Netherlands.

- Length at study initiation (mean and SD): 3.5 ± 0.2 cm
- Weight at study initiation (mean and SD): 0.52 ± 0.07 g

HOLDING / ACCLIMATION
- Acclimation period: At least 12 days after delivery
- Acclimation conditions (same as test or not): same
- Type and amount of food during acclimation: Pelleted fish food (Essence (300-500 µm), Coppens International bv, Helmond, The Netherlands)
- Feeding frequency during acclimation: Daily
- Health during acclimation (any mortality observed): In the batch of fish used for the test, mortality during the seven days prior to the start of the test was less than 5%.

FEEDING DURING TEST
No feeding from 24 hours prior to the test and during the total test period

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

1.8 mM (180 mg CaCO3/L)

Test temperature:

20 - 21 °C

pH:

7.5 - 8.1

Dissolved oxygen:

≥ 6.6 mg/L (>60% oxygen saturation)

Nominal and measured concentrations:

nominal loading rate: 100 mg/L (undiluted saturated solution = 100% SS)
measured test concentrations: test start: 0.049 mg/L; test end (96 h): 0.014 mg/L; calculated geometric mean: 0.026 mg/L.
The measured concentration of 0.049 mg/L was expected to be above the solubility limit of the test item in test medium. This was based on the analytical results of range-finding test and on the observed decrease of test item concentration during the limit test.

Details on test conditions:

TEST SYSTEM
- Test vessel: 10 litres, all-glass, containing 9 liters of test medium
- Type (delete if not applicable): open
- Aeration: none
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.40 g fish wet weight/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: adjusted ISO medium, formulated using RO-water (tap-water purified by reverse osmosis; GEON Waterbehandeling, Berkel-Enschot, The Netherlands)
Composition: CaCl2.2H2O: 211.5 mg/L, MgSO4.7H2O: 88.8 mg/L, NaHCO3: 46.7 mg/L, KCl: 4.2 mg/L.
- Ca/Mg ratio: 4:1
- Culture medium different from test medium: no
- Intervals of water quality measurement: temperature, dissolved oxygen and pH: daily in all vessels, beginning at the start of the test (day 0)

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hour photoperiod daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality and sub-lethal effects; recorded at 2¾, 24, 48, 72 and 96 hours following the start of exposure. In addition, every afternoon from day 0 to observe for any dead or severely distressed fish.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable (limit test)
- Range finding study
- Test concentrations: 0.10, 10 and 100% of a supersaturated solution (SS) prepared at a loading rate of 100 mg/L
- Results used to determine the conditions for the definitive study: no mortality was observed at any of the test concentrations during the test period. Fish exposed to the undiluted SS were observed to be hyperactive after 24 hours of exposure but this behaviour was not observed during the remaining part of the test. The expected LC50 was above the concentration obtained in a SS prepared at 100 mg/L.

Reference substance (positive control):

yes

Remarks:

Pentachlorophenol at 0.10, 0.22 and 0.46 mg/L

Key result

Duration:

96 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mortality (fish)

Remarks on result:

other:

Remarks:

supersaturated solution prepared at 100 mg/L

Key result

Duration:

96 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

other: mortality and sub-lethal effects

Remarks on result:

other:

Remarks:

supersaturated solution prepared at 100 mg/L

Details on results:

- Behavioural abnormalities:
- Other biological observations: none; all fish survived and no visible abnormalities were observed.
- Mortality of control: none
- Other adverse effects control: none
- Abnormal responses: none

Results with reference substance (positive control):

- Results with reference substance valid? yes
- LC50: 0.15 mg/L (95 % confidence interval between 0.10 and 0.22 mg/L)
- Other: historical range: 0.10 – 0.46 mg/L

Reported statistics and error estimates:

The NOELR was determined directly from the raw data. The LOELR, LL100 and LL50 at the observation times could not be quantified due to the absence of a toxic effect of the test item at the tested loading rate.

Validity criteria fulfilled:

yes

Remarks:

/no mortality of control animals; concentration of dissolved oxygen in all test vessels >60% of the air saturation; test conditions were maintained constant throughout the test

Description of key information

effect value for carp (Cyprinus carpio), (OECD 203): 96-h LL50: > 100 mg/L (undiluted saturated solution)

Additional information

LL50 for freshwater fish: > 100 mg/L.

The results indicate that the test material is not toxic to fish up to the limits of its solubility (< 1 mg/L in test water) and a NOEC and thus a PNEC cannot be determined.