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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June 04 to June 25, 2010
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
yes
Remarks:
temperature variation during the test and during test substance storage. Expected to be without impacts on study relevance.
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Observations were taken at 2, 24, 48, 72 and 96 hours for mortality and sublethal effects. Dead fish were removed daily.
Vehicle:
no
Details on test solutions:
The lowest EC50 value of existing relevant algae or acute invertebrate tests (in this case daphnia) was set as threshold concentration. This threshold approach was performed in order to demonstrate that the test item has no toxic effects on the test fish up to the threshold concentration in order to spare use of vertebrates. A nominal concentration of 0.24 mg test item/L was tested against a control group. The test medium with the only test item concentration of nominal 0.24 mg/L was prepared by dissolving 2.4 µL of the test item homogeneously in 10000 mL test water by intense stirring for two minutes. The test medium was prepared just before introduction of the fish.
Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
Species: Zebrafish (Danio rerio)
Age and Size: Juveniles;
The mean body length of the fish* in the test was 1.86 cm ± 0.25 cm (Mean ± SD), the mean body wet weight 0.056 ± 0.016 g (Mean ± SD).
* 10 fish from the test fish batch were measured before the start of the test
Sex: Male and female
Origin: The test fish were obtained from Aquaristik-Studio Fröhlich, 63165 Mühlheim, Germany
Holding Conditions: All fish were obtained and held in the laboratory for at least 12 days before the start of the test. They were held in water of the quality to be used in the test for at least seven days immediately before testing under the following conditions:
Light: 12 - 16 hours photoperiod daily
Temperature: 23 - 24 °C
Oxygen concentration: at least 80 % of the air saturation value
Feeding: three times per week or daily until 24 hours before the test was started
During the last 7 days prior to the start of the test no fish (0 %) died in the test fish batch. Therefore the mortalities in the fish batch were below 5 % and the fish batch was accepted.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
No data reported.
Test temperature:
21-24°C
pH:
7.7-8.1
Dissolved oxygen:
96 - 100% of air saturation. Test water not aerated.
Salinity:
No data reported
Nominal and measured concentrations:
In the freshly prepared test media 29 % of the nominal test concentrations were found. In the aged test media approximately 46 % of the nominal test concentration was found, corresponding to an arithmetic mean measured concentration of 0.088 mg test item/L and a control. All biological endpoints were based on the arithmetic mean concentration. The lowest EC50 value of existing relevant algae or acute invertebrate tests (in this case daphnia) was set as threshold concentration. This threshold approach was performed in order to demonstrate that the test item has no toxic effects on the test fish up to the threshold concentration.
Details on test conditions:
Test Environment: Controlled environmental room
Measurement of pH-Values, Dissolved Oxygen and Water Temperature: The water temperature, pH-values and the dissolved oxygen concentrations were determined daily in the test media of the only treatment group.
pH-Values of the Test Water: 7.7 to 8.1 (see Table 4)
Dissolved Oxygen Concentrations:
96 % - 100 % of the air saturation value (see Table 5)
Water Temperature: 21 °C - 24 °C (see Table 6)
Light Regime: 16 h light : 8 h dark;
30 min dawn/dusk period was provided
Light Intensity: 600 - 880 lux
Recording: Test conditions were recorded with suitable instruments and documented in the raw data.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.088 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC0
Effect conc.:
>= 0.088 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
No mortality and no sublethal effect occurred during the test.
Reported statistics and error estimates:
An arithmetic mean was used for calculating all endpoint concentrations.
Validity criteria fulfilled:
yes
Conclusions:
The toxicity to fish of polysulphides, di-tert-butyl has been assessed using zebrafish (Danio rerio), based on the measured concentrations. The 96-hour LC50 is >0.088 mg/L, the NOEC is >= 0.088 mg/L.
Executive summary:

Toxicity of polysulfides, di-tert-butyl on fish was investigated in a OECD TG 203 GLP-compliant study. The threshold approach was followed, where the tested concentration is the lowest of the two EC50 obtained in the two toxicity tests on invertebrate and algae (0.24 mg/L). Based on the test results the 96-hour LC50 of Polysulfides, di-tert-butyl for zebrafish (Danio rerio) was determined to be higher than 0.24 mg test item/L based on the nominal test concentration. Based on the mean measured concentration of the test item the 96-hour LC50was determined to be higher than 0.088 mg/L. The no observed effect concentration (NOEC) was determined to be = 0.24 mg test item/L and the LOEC was determined to be > 0.24 mg test item/L, both values also based on the nominal test concentration. Based on the mean measured concentration of the test item the no observed effect concentration (NOEC) was determined to be = 0.088 mg test item/L and the LOEC was determined to be > 0.088 mg test item/L.

The large uncertainties about real exposure concentrations do not prevent to conclude qualitatively that no acute effect to fish is observed at saturation in the medium

Description of key information

One study according to OECD TG 203 has been carried out on Danio rerio. No effect was observed in a limit test carried out at saturation. In spite of uncertainties in the reported concentrations, it can qualitatively be concluded that no acute toxicity to fish is observed with tert-butyl polysulfide up to the lowest EC50 for invertebrates and algae..

Key value for chemical safety assessment

Additional information

Based on the test results the 96-hour LC50of Polysulfides, di-tert-Bu for Zebrafish(Danio rerio)was determined to be higher than 0.24 mg/L based on the nominal test concentration. Based on the mean measured concentration of the test item the 96-hour LC50was determined to be higher than 0.088 mg/L. The no observed effect concentration (NOEC) was determined to be = 0.24 mg/L and the LOEC was determined to be > 0.24 mg/L, both values also based on the nominal test concentration. Based on the mean measured concentration of the test item the no observed effect concentration (NOEC) was determined to be = 0.088 mg/L and the LOEC was determined to be > 0.088 mg/L.