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Ecotoxicological information

Short-term toxicity to fish

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short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
equivalent or similar to guideline
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
not specified
Analytical monitoring:
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
- Common name: rainbow trout (Oncorhynchus mykiss)
- Source: Goosen's Trout Farm, Otterville, ON (Canada)
- Age at study initiation (mean and range, SD): not reported
- Length at study initiation (length definition, mean, range and SD): 4.6-6.4 cm
- Weight at study initiation (mean and range, SD): 1.2-3.8 g
- Feeding during test: not reported

- Acclimation period: at least 7 d
- Acclimation conditions (same as test or not): yes
- Type and amount of food: Ewos trout pellets
- Feeding frequency: daily
- Health during acclimation (any mortality observed): not reported
Test type:
Water media type:
Limit test:
Total exposure duration:
96 h
no data
Test temperature:
Dissolved oxygen:
5.6-9.4 mg/L
no data
Nominal and measured concentrations:
0 (control), 10, 18, 32, 56, 100% of the maximum test concentration (not further specified)
Details on test conditions:
- Test vessel: >=14 L tank
- Type: not reported
- Material: not reported
- Size: >=14 L
- Headspace: not reported
- Fill volume: 14 L
- Aeration: no
- Type of flow-through (e.g. peristaltic or proportional diluter): diluter according to Mount-Brungs (1967)
- Renewal rate of test solution (frequency/flow rate): 21-111 mL/min; 95% replacement time: 6-33 h
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- Biomass loading rate: 0.8-2.7 g/L

- Source/preparation of dilution water: the water for stock and bioassay tanks was a municipal supply drawn from Lake Ontario. The water was dechlorinated to < 10 µg Cl/L
- Alkalinity: 86 mg/L as CaCO3
- Conductivity: 340 µmhos/cm²
- Culture medium different from test medium: the test medium was the same as during the acclimation period
- Intervals of water quality measurement: not reported

- Adjustment of pH: no
- Photoperiod: 16 h light/8 h dark
- Light intensity: not reported

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality

- Spacing factor for test concentrations: ca. 1.8
- Range finding study
- Test concentrations: 1, 10, 100, 1000 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
96 h
Dose descriptor:
Effect conc.:
0.638 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Details on results:
- Behavioural abnormalities: not reported
- Observations on body length and weight: not reported
- Other biological observations: not reported
- Mortality of control: 1.25% in all aqueous bioassays
- Other adverse effects control: not reported
- Abnormal responses: not reported
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: not reported
- Effect concentrations exceeding solubility of substance in test medium: no
Reported statistics and error estimates:
Probit analysis or graphical method, multiple regression analysis and chi-square tests
Validity criteria fulfilled:
not specified
The acute toxicity of hydroquinone to Oncorhynchus mykiss was investigated in a study conducted similar to OECD Guideline 203. The 96 h LC50 was determined to be 0.638 mg/L (measured).
Executive summary:

The acute toxicity of hydroquinone to Oncorhynchus mykiss was investigated in a study conducted similar to OECD Guideline 203 (Fish, Acute Toxicity Test). The fish were exposed to 6 concentrations and one control for 96 h under flow-through conditions. The test substance concentrations were measured daily via UV absorbance. The assay method was the measurement of the absorbance of ultraviolet light by the test solutions in a quartz cell with a 1-cm path length. Concentrations were calculated by reference to standard curves of the chemical dissolved in control tank water. For hydroquinone the concentration/calibration curve was not linear within the test concentration range. The wavelength at which the chemical absorbed maximally was identified by scanning a standard solution. Appearance of more than one peak in the test solutions indicated whether or not the compound was degrading during the exposure. No details of the analytical results, however, were reported. Due to the known instability of hydroquinone in aqueous solution this information would have been of great importance. The 96 h LC50 was determined to be 0.638 mg/L (=5.8 µmol/L; measured). Fish length, water temperature, loading, pH and water hardness are in accordance with the recommendation of the current OECD Guideline 203.

This study is regarded as reliable with restrictions due to the missing raw data.

Description of key information

In a study conducted comparable to OECD Guideline 203 and under flow-through conditions, a 96 h LC50=0.638 mg/L was determined using Oncorhynchus mykiss as test organism. 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Dose descriptor:
Effect concentration:
0.638 mg/L

Additional information

Three acute tests with two freshwater species are available (Onchorhynchus mykiss, Pimephales promelas) with 96 h LC50 values of 0.044, 0.097 and 0.638 mg/L. Concerning the effects on fish the study of Hodson et al. (1984) and the LC50=0.638 mg/L is preferred because the test performance generally fulfills the requirements of the OECD Guideline 201, contrary to the other two tests.