Molybdenum, bis(N,N-dibutylcarbamodithioato-κS,κS')dioxodi-μ-thioxodi-, stereoisomer

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:

Duplicate samples for analysis were taken from the single WAF and the control.
Frequency: at t=0 h and t=96 h
Volume: 2.0 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 of 100 mg/L. Thus, preparation of the test solution 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. Thereafter, the Water Accommodated Fraction (WAF) was collected by means of filtration through a 0.45 µm membrane filter (Supor®, Pall Corporation) and used as 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): 2.5 ± 0.1 cm
- Weight at study initiation (mean and SD): 0.52 ± 0.09 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:

7.7 - 8.1

Dissolved oxygen:

≥ 6.6 mg/L (>60% oxygen saturation)

Nominal and measured concentrations:

nominal loading rate: 100 mg/L (WAF)
measured test concentrations: test start: 0.046 mg/L and < LOQ (0.001 mg/L); test end (96 h): < LOQ

The measured concentration of 0.046 mg/L was regarded as not reliable since the solubility limit of the test item has been shown to be < 0.001 mg/L (the LOQ of the analytical method used) during the range-finding test as well as in an acute toxicity study with daphnia and in an algal growth inhibition test (Test Facility Study No. 20148112 and 20148113).

Details on test conditions:

TEST SYSTEM
- Test vessel: 10-litres all-glass vessels, containing 8 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: 0.46 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 2½, 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: WAFs prepared at loading rates of 1.0, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: No mortality or clinical effects were observed at any of the WAFs during the test period. Therefore, the expected LL50 was above the concentration obtained in a WAF 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:

WAF prepared at a loading rate of 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:

WAF prepared at a loading rate of 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 and LL50 were determined directly from the raw data.

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 (WAF)

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 μg/L in test water) and a NOEC and thus a PNEC cannot be determined.