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Ecotoxicological information

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:
03 December 2013 - 12 November 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Vehicle:
yes
Details on test solutions:
The method of preparation used during the definitive test was based on the results of formulation trials performed as part of another study for TCD (HLS Study Number
VHJ0064), together with a range finding test and a main test conducted as part of this study. The test substance (190, 86.4, 39.3 or 17.8 mg) was added to tetrahydrofuran (THF; ca. 2
mL) in a volumetric flask (10 mL), made up to volume and mixed to provide solvent stock solutions at 19.0, 8.64, 3.93 and 1.78 mg/mL. An aliquot (4.56 mL) of the solvent stock
solution at 1.78 mg/mL was added to a volumetric flask (10 mL) containing ca. 3 mL of THF, made up to volume with THF and mixed to provide an additional solvent stock solution
at 0.811 mg/mL.

An aliquot (2.3 mL) of the appropriate solvent stock solution was added to ca. 22 L dilution water in a glass aspirator (23 L); the contents were mixed well and then adjusted to volume
with additional dilution water prior to sealing with a silicone bung. This provided test media with nominal concentrations of 1.90, 0.864, 0.393, 0.178 and 0.0811 mg/L as TCD.
As an intermediate vehicle was used to facilitate the preparation of the test medium, an additional control group, in a sealed glass aspirator, containing THF and dilution water (2.3
mL THF with 23 L diluent water to give a concentration of 100 μl/L of THF) was included in the study providing the same concentration of auxiliary substance as present in the test media.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
The fish were supplied by a commercial fish farm in the UK and were reared at the farm from eggs that hatched in July 2015.

The stock of fish was obtained from the supplier on 25 August 2015 and they were held in an aerated supply of diluent water under flow-through conditions until use. During the 14-day
period immediately before the definitive test, temperatures remained within the range 13.7 to 14.1°C, pH values within the range 7.96 to 8.32, dissolved oxygen concentrations within the
range 94 to 101% air saturation value (ASV) and total hardness within the range 142 to 172 mg/L as CaCO3.

The fish were fed daily with an amount of commercial fish food (TROUW (UK) Ltd; Nutra Fry 02) equivalent to 1.25-1.5 % of the total wet-weight of fish in the holding tank. No
food was given during the 24-hour period immediately before exposure or during the exposure period itself. No medication was given during the holding period, and no mortality
was recorded during the 14 days before the definitive test. The size of the fish used in the definitive test was determined by weighing and measuring a sample of ten fish taken at random from the holding tank on 8 October 2015; their mean total length was 5.57 cm and their mean wet weight was 1.523 g.

The water used to hold the fish and for the study was laboratory tap water, dechlorinated and softened by passage through a water purification system. It was passed through a high grade
activated carbon filter to remove chlorine and any organic contaminants. A proportion of the supply then passed through a water softener before final reverse osmosis treatment to produce
a highly purified water supply. The two grades of dechlorinated water were then remixed to give a supply with the desired water hardness. This water was then held in an intermediate
tank where it was equilibrated to the test temperature and gently aerated before being supplied to the holding and test areas.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
149 - 172mg/L as CaCO3
Test temperature:
13.5 - 14.6°C
pH:
7.51 - 8.16
Dissolved oxygen:
72 - 103% Air Saturation Value
(100%ASV = 9.09mgO2/L at 20°C)
Nominal and measured concentrations:
Nominal: 0.0811, 0.178, 0.393, 0.864, 1.90 mg/L
Measured: 0.0417, 0.101, 0.185, 0.561, 0.904 mg/L
Measured values are the overall geometric mean of measured concentrations of resh and expired media throughout the exposure period. No test material was found in the control or solvent control groups.
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
0.116 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% Confidence limits: 0.0913 - 0.140 mg/L
Key result
Duration:
96 h
Dose descriptor:
LOEC
Effect conc.:
0.101 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Key result
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
0.042 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of TCD to rainbow trout (Oncorhynchus mykiss) has been assessed under semi-static conditions using a sealed test system.
Based on mean measured concentrations, the 96 hour LC50 was 0.116 mg/L (95% confidence limits of 0.0913 and 0.140 mg/L), and the no observed effect concentration was 0.0417 mg/L.

Description of key information

The acute toxicity of TCD to rainbow trout (Oncorhynchus mykiss) has been assessed under semi-static conditions using a sealed test system.

Based on mean measured concentrations, the 96 hour LC50 was 0.116 mg/L (95% confidence limits of 0.0913 and 0.140 mg/L), and the no observed effect concentration was 0.0417 mg/L.

Key value for chemical safety assessment

LC50 for freshwater fish:
0.116 mg/L

Additional information