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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
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study according to Official Jounal of the European Communities No. L251 Part C: C1 Acute toxicity for Fish
according to guideline
OECD Guideline 203 (Fish, Acute Toxicity Test)
GLP compliance:
Analytical monitoring:
Details on sampling:
- Concentrations: 50, 17, 5, 2, 0.7 mg/L
- Sample storage conditions before analysis: all samples were analyzed on the day taken
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test material and dilution water were stirred in sealed vessels for 24 hrs. The mixture was then allowed to settle for 1 hr. The aqueous phase was then drawn off and used as the test medium.
- Controls: diluent water only
- Evidence of undissolved material (e.g. precipitate, surface film, etc): Excess test material was noted after stirring at all concentrations of 2 mg/l and above.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
- Common name: Rainbow trout
- Source: Zeals Trout Farm, Wiltshire
- Age at study initiation (mean and range, SD): fingerlings
- Length at study initiation (length definition, mean, range and SD): 3.3 to 4.4 cm, mean 3.8 cm
- Weight at study initiation (mean and range, SD): 0.38-0.94 g, mean 0.67 g
- Feeding during test: no

- Acclimation period: 9 days
- Acclimation conditions (same as test or not): same as test conditions for 7 days preceding test
- Type and amount of food: Mainstream Trout Food No. 03, BP Nutrition Ltd.
- Feeding frequency: not fed 24 hrs prior to test
- Health during acclimation (any mortality observed): fish not used for testing if mortality exceeds 5% or if there is apparent disease

Test type:
Water media type:
Limit test:
Total exposure duration:
96 h
Post exposure observation period:
96 hrs
196-248 mg/l CaCO3
Test temperature:
14.8-15.3 °C
Dissolved oxygen:
6.3-9.8 mg/l
Nominal and measured concentrations:
Nominal: 50, 17, 5, 2, 0.7, 0 mg/l
Measured: 22.4, 9.3, 2.8, 1.2, <1.0, <1.0 mg/l
Details on test conditions:
- Test vessel:
- Type (delete if not applicable): sealed with glass plates
- Material, size, headspace, fill volume: 11 l glass tanks completely filled with test medium
- Renewal rate of test solution (frequency/flow rate): daily
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1

- Source/preparation of dilution water: Received as laboratory main supply from Mid Kent Water Company, chlorinated to 0.1 mg/l. Water is then passed through a 10 µm filter, activated carbon, and finally aerated to remove chlorine.
- Particulate matter: 364 mg/l
- Metals: ~120 mg/l
- Chlorine: <0.2 mg/L
- Alkalinity: 264 mg/l
- Ca/mg ratio: 110/2.6
- Conductivity: 522 µS/cm
- Intervals of water quality measurement: approx. 6 months

- Photoperiod: 16 hrs light/8 hrs dark
- Light intensity: artificial light

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality, toxicity at 6, 24, 48, 72, and 96 hr
Reference substance (positive control):
Key result
96 h
Dose descriptor:
Effect conc.:
9.2 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: 5.5 - 15 mg/l
Details on results:
- Behavioural abnormalities: All fish at the 5.0 mg/l concentration showed toxic symptoms beginning at the 6 hr observation. By the 24-hr observation these fish were swimming abnormally. By the 96-hr observation, the fish had recovered. All fish at the 17.0 mg/l and 50.0 mg/l concentrations died by the first observation.
- Mortality of control: No
- Other adverse effects control: No
Sublethal observations / clinical signs:

Summary of other short-term fish toxicity studies.

End Point Study Reference  
REACH requirement IUCLID Section Study Name Data Waiving Waiving Justification Species Study Result Type Test Guideline/Qualifier Test Guideline/Guideline Test Guideline/Deviations Reliability Rational For Reliability GLP Compliance Test Materials/Identity Study Result Reference Type Reference Author Reference Year Reference Title Bibliographic Source Testing Laboratory Reference Report No. Owner Company Company Study No. Report Date Data access
9.1.3 Short term aquatic toxicity on fish 6.1.1 Acute Fish Toxicity Test with Rainbow Trout Oncorhynchus mykiss experimental result According to  FIFRA 72-1 1 Well-documented GLP study. yes C8-C10 Aromatics, Predominantly C9 Alkylbenzenes 96-hr LL50 = 18.0 mg/L (WAF) study report ANON 1992 Acute Fish Toxicity Test with Rainbow Trout HSPA0158 Exxon Biomedical Sciences, Inc. ExxonMobil Petroleum & Chemical BVBA 111758 yes
Validity criteria fulfilled:
The 96-hr LL50 for fish is 9.2 mg/L (WAF).
Executive summary:

The purpose of this study was to determine the acute toxicity of Hydrocarbons, C9, aromatics to the fish O. mykiss. Groups of 10 fish were exposed to 0, 0.7, 2.0, 5.0, 17.0, or 50.0 mg/l (WAF) of test substance. The fish were exposed for 96 hrs, in a semi-static exposure. Animals were examined for mortality and signs of toxicity at 6, 24, 48, 72, and 96 hrs of exposure. All animals in the 17.0, and 50.0 mg/l exposure groups died by the first observation at 6 hrs. All other animals survived. Based on mortality, the 96 -hr LL50 for fish is 9.2 mg/l (WAF).

Description of key information

There is data available for this substance. Key data is summarized below.

The acute toxicity of hydrocarbons, C9 aromatics as measured by mortality to rainbow trout (Oncorhynchus mykiss) was evaluated in freshwater. Under the conditions of this study, C9 aromatics hydrocarbons produce acute lethal toxicity to Oncorhynchus mykiss at 9.2 mg/L, based on nominal loading of the test substance in water.

Key value for chemical safety assessment

Additional information

Water accommodated fractions of hydrocarbons, C9, aromatics, produced a 96-hour LL50 value of 9.2 mg/L with rainbow trout, Oncorhynchus mykiss.


C9, aromatics are hydrocarbon UVCBs that pose an acute aquatic hazard. The hydrocarbon block method is used for environmental risk assessment (see REACH guidance, R7, app.13-1). Aquatic PNECs for hydrocarbon blocks have been derived using the HC5 statistical extrapolation method and the target lipid model using representative structures. See Product Library tab in PETRORISK spreadsheet attached to Section 13 of the dossier. Given the large database of freshwater organisms included in the target lipid model, an assessment factor of one has been applied to the HC5.


In the WAF methodology, different loadings of the substance are added to the test medium and equilibrium between the water and the hydrocarbons is achieved according to their specific water solubility. The hydrocarbon concentrations at equilibrium will be characteristic of the loading of the substance, and therefore toxicity values from WAF studies are expressed as effect loadings or lethal loadings (EL or LL), not as concentrations. These effect loadings are used to determine environmental classifications. The WAF methodology is widely accepted for the testing of complex hydrocarbon substances and other UVCBs, and it has been incorporated in different guidance documents, including the REACH guidance.