2-ethylhexyl 10-ethyl-4-[[2-[(2-ethylhexyl)oxy]-2-oxoethyl]thio]-4-methyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Guideline study conducted under GLP. Exposure concentrations, measured on the basis of total Sn and converted to and reported as the test substance [MMT(2-EHTG)] using the conversion factor [743.7/118.71] consisting of the Mol weights of the test substance and Sn, respectively. This approach includes more water-soluble tin impurities and hydrolysis products. All measured Sn was attributed to the named substance. The preparation of the WAF allowed both a solubilized portion of the test substance and the hydrolysis products to be present in the study. Only the control and the 2 highest exposure concentrations (56 and 100% of the WAF) were measured for total Sn content, as these higher concentrations were considered essential for the determination of toxicity. The 100% WAF was slightly hazy throughout the test period. No test substance film or precipitate were observed. Exposure concentrations were not stable, and exposure concentrations were not maintained at or above 80% of the initial concentration during the 24 h replacement periods. Analytical repeatability was very low due to the low solubility of the named substance. This is not unexpected given the low water solubility of the named substance and its instability in water.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

The temperature measured in the test solutions during the test period was occasionally below the lowest concentration of the optimal range as prescribed by the protocol (i.e. between 21 and 25 degrees C). However, this decrease was only marginal, i.e. n

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

yes

Remarks:

The separation of the WAF differed from what was prescribed by the protocol as a consequence of practical problems regarding the relatively high test volumes. Glass aquarium tanks were used for in-between separation and the stabilization period was half

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Nominal: 0, 56 and 100 % of a water accommodated fraction (WAF) prepared at a loading rate of 100 mg/L
Measured: mean measured concentrations of Sn in the 0, 56 and 100 % WAF were <4.5, 580 and 960 ug Sn/L
Equivalent calculated: 0, 56 and 100 % WAF were 0, 3.6 and 6.0 mg/L as MMT(EHTG)
- Sampling method: Duplicate 25 mL samples were taken at t = 0h and t = 72 h from freshly prepared solutions and at t = 24h and t = 96 h from 24 hour old solutions.
- Sample storage conditions before analysis: samples were stored at room temperature for a maximum of seven days until transportation to the place of analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Preparation of the test solutions started with a dispersion of the stock solution in test medium at a nominal loading of 100 mg/L. The dispersion was stirred for approximately 24 hours applying either a magnetic stirrer (combined limit/range-finding test) or an ultra thurrax (final test), after which it was left to satbilise for approximately one hour (range-finding) or half an hour (final test). Subsequently, the water fraction was separated from the undissolved fraction of test substance by means of siphoning into a separation funnel or a glass aquarium. After another short stabilisation period in the separaition funnel or glass aquarium, the Water Accomodated Fraction (WAF) was collected for use in the test. The lower test concentrations were prepared by subsequent dilution of the WAF in test medium. All test vessels were pre-conditioned for 30 minutes with approximately 1 litre of the corresponding test solutions prior to the start of the test. Test solutions were daily renewed according to the above procedure
- Differential loading: loading rate 100 mg/L
- Controls: Test medium without test substance or other additives (0 mg/L)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): none
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): N/A
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no test substane film or precipitate were observed.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebra fish
- Strain: Brachydanio rerio
- Source: commercial hatchery, Atlanta, Hellevoetsluis, The Netherlands
- Age at study initiation (mean and range, SD): no data
- Length at study initiation (length definition, mean, range and SD): mean 3.0 ± 0.1 cm; standard deviation less than 25 %
- Weight at study initiation (mean and range, SD): mean 0.53 ± 0.14 g
- Method of breeding: no data
- Feeding during test: No feeding from 48 hours prior to the test and during the total test period

ACCLIMATION
- Acclimation period: at least 12 days after delivery
- Acclimation conditions (same as test or not): same as test
- Type and amount of food: Trouvit
- Feeding frequency: daily
- Health during acclimation (any mortality observed): no data

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

none

Hardness:

250 mg CaCO3 per liter

Test temperature:

21 to 25 °C

pH:

7.9 to 8.0

Dissolved oxygen:

>60 % of air saturation
oxygen content 7.0 to 9.8 mg/L

Salinity:

no data

Nominal and measured concentrations:

nominal: 10, 18, 32, 56 and 100% of a WAF
measured concentration of tin in the 0, 56 and 100 % WAF were <4.5, 580 and 960 µg Sn/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 10 liters, all glass- preconditioned
- Material, size, headspace, fill volume: glass
- Aeration: aerated until the dissolved oxygen concentration had reached saturation and the pH had stabilised; the test media were not aerated during the test
- Type of flow-through (e.g. peristaltic or proportional diluter): semi-static
- Renewal rate of test solution (frequency/flow rate): daily
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- No. of vessels per vehicle control (replicates): n/a
- Biomass loading rate:7 fish per 9 litres of test media

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ISO medium formulated using Milli-Ro water (tap-water purified by reverse osmosis; Millipore corp, Bedford, Mass., USA)
CaCl2.2H2O 293.8 mg/L
MgSO4.7H2O 123.3 mg/L
NaHCO3 64.8 mg/L
KCL 5.8 mg/L
- Culture medium different from test medium: no
- Intervals of water quality measurement: once per week

OTHER TEST CONDITIONS
- Adjustment of pH: no adjustment
- Photoperiod: 16 hours photoperiod daily
- Light intensity: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality and other effects; At 2-4, 24, 48, 72 and 96 hours following the start of the exposure. Fish length and weight: ten fish of the batch used for the test were weighed and measured prior to the start of the test.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: the concentration range has to cover at least one concentration causing no mortality, one or more concentrations causing 10-90 % mortality and one concentration causing 100% mortality.
- Range finding study- combined limit test/ range-finding study
- Test concentrations: 0.1, 1.0, and 10% of the WAF prepared at a loading rate of 100 mg/L
- Results used to determine the conditions for the definitive study: The analytical results could not be relied upon because of tin contamination in the control samples and were therefore rejected. Some effects were observed, but these could not reliably be attributed to either contamination and/or toxicity cause by the test substance concentrations. Consequently, the final test was carried out as a concentration series.

Reference substance (positive control):

yes

Remarks:

pentachlorophenol (PCP)

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

3.6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: mg monomethyltin (ethylhexylthioglycolate) per liter

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 6 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: mg monomethyltin (ethylhexylthioglycolate) per liter

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: 1 fish from the 100 % WAF was observed swimming slowly at 8 and 72 h as compared to the control fish.
- Observations on body length and weight: none
- Other biological observations: 1 fish from the 100 % WAF group died at 48 h.
- Mortality of control: none
- Other adverse effects control: none
- Abnormal responses: none
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no test substance film or precipitate was observed.

No LC50 could be caluclated because the test substance proved to be non-toxic. The LC50 was greater than the maximum soluble concentration.

Results with reference substance (positive control):

- Results with reference substance valid? yes; concentrations: 0.06, 0.10, 0.15, 0.22 and 0.32 mg/L
- Mortality: 20 % at 0.22 mg/L; 100 % at 0.32 mg/L
- LC50: 96h 0.24 mg/L
- Other: no data

Reported statistics and error estimates:

not performed

Validity criteria fulfilled:

yes

Conclusions:

Under the conditons of the test, monomethyltin (ethylhexylthioglycolate) induced no visible effects in zebra-fish at or below 56 % WAF (prepared at a loading rate of 100 mg/L)

Executive summary:

A 96 -hour acute toxicity study in zebra-fish was performed in accordance with OECD guideline number 203. Water accommodated fractions were prepared for testing. Fish were exposed to test groups corresponding to 10, 18, 32, 56 and 100 % of a WAF prepared at a loading rate of 100 mg/L. Samples for analytical confirmation of actual exposure concentrations were taken from freshly prepared solutions at t = 0 h and t = 72 h and from 24 h old solutions at t = 24 h and t = 96 h. The test substance induced no visible effects in zebra fish at or below a concentration containing 56 % of a WAF. Based on average measured concentrations the NOEC corresponded to 3.6 mg/L. The 96-h LC50 for zebrafish exposed was above a WAF prepared at a loading rate of 100 mg/L. Based on average measured concentrations this corresponded to a 96-h LC50 of >6.0 mg/L.

Description of key information

LC50 (96-h) > 6 mg/L in zebrafish (Brachydanio rerio)  (OECD TG 203)

Additional information

In an OECD 203 acute toxicity study, zebrafish (Brachydanio rerio) were exposed for 96 hours to the test substance. No visible effects were induced at or below a concentration containing 56 % of a water accommodated fraction (WAF) prepared at a loading rate of 100 mg/L. Based on average measured concentrations the NOEC corresponds to 3.6 mg/L. The 96 -hr LC50 was above a WAF prepared at a loading rate of 100 mg/L. Based on average measured concentrations this corresponded to a 96 -hr LC50 >6.0 mg/L.