Farnesol

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across hypothesis is based on different compounds with qualitatively similar properties using the analogue approach, following Scenario 2 of the Read-Across Assessment Framework (ECHA 2017).

2. SOURCE AND TARGET CHEMICAL(S)
Target substance: Farnesol (CAS: 4602-84-0; EC: 225-004-1)
Source substance: Nerolidol (CAS: 7212-44-4; EC: 230-597-5)

3. ANALOGUE APPROACH JUSTIFICATION
For the prediction of environmental effects, farnesol and nerolidol have similar levels of acute aquatic effects and supporting data are available for farnesol for the read-across endpoint. Both substances have similar bioaccumulation potential and degradation is accounted for in the source study (by maintaining test item concentrations) so that degradation effects do not affect the prediction. Farnesol may undergo Michael-type addition reactions at the end hydroxyl group, however reaction may be inhibited by steric hindrance. Indicative experimental data for farnesol suggest that toxicity effects in the predicted endpoint are not worse than observed for nerolidol.

4. DATA MATRIX
See "Read-across justification" in Section 13.2.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1.43 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: CL: 1.30 to 1.58 mg/L

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1.34 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

behaviour

Remarks on result:

other: CL: 1.22 to 1.48 mg/L

Details on results:

- Behavioural abnormalities: Affected fish lost schooling benaviour, swam near the tank bottom and were hypoactive. They were also underreactive to external stimuli, had increased respiration, were darkly coloured and lost equilibrium prior to death.

Validity criteria fulfilled:

not specified

Conclusions:

The 96-hour LC50 value for Pimephales promelas was determined to be 1.43 mg/L.

Executive summary:

Pimephales promelas were exposed to nerolidol for 96 hours. The LC50 was determined to be 1.43 mg/L and the EC50 for behavioural abnormalities was determined to be 1.34 mg/L. The guideline and GLP status of the study are unknown, however the study was well-reported and is reliable with restrictions (Klimisch 2). This data may be used as key data, as nerolidol is a suitable read-across source to the target substance based on similar chemical structure and hazard data.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 August 1986 - 15 August 1986

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Study guideline and GLP status unknown, however study is well-reported.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: Fish were exposed to 5 concentrations of the test item alongside a control for 96 hours.
- Short description of test conditions: 25.5 °C, pH 8.0, 60 mg/L dissolved oxygen, 44.5 mg/L CaCO3 (hardness), 40.8 mg/L CaCO3 (alkalinity). Average measured concentrations varied up to 3.40% of nominal concentrations.
- Parameters analysed / observed: Mortality and clinical sings were observed at 0, 5, 24, 47, 72 and 96 hours.

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A toxicant stock prepared by diluting the test substance to a concentration of 17.7 mg/L. The stock was stirred.

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Age at study initiation (mean and range, SD): 32 days
- Length at study initiation (length definition, mean, range and SD): 18.7 mm (SD: 3.404mm)
- Weight at study initiation (mean and range, SD): 0.073 g (SD: 0.0365 g)

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

96 h

Hardness:

44.5 mg/L CaCO3

Test temperature:

25.5 °C

pH:

8.0

Dissolved oxygen:

7.0 mg/L

Nominal and measured concentrations:

Nominal concentrations of 0 (control), 0.64, 0.98, 1.50, 2.30 and 3.54 mg/L
Measured (and corrected) concentrations of < 0.16 (control), 0.63, 0.98, 1.48, 2.34 and 3.40 mg/L
Recovery: 92.6 %

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 2.0 L tank volume
- Renewal rate of test solution (frequency/flow rate): 18 v/d additions
- No. of organisms per concentration (replicates): 20
- No. of organisms per control (replicates): 20
- Biomass loading rate: 0.730 g/L

TEST MEDIUM / WATER PARAMETERS
- Alkalinity: 40.8 mg/L

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1.43 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: CL: 1.30 to 1.58 mg/L

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1.34 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

behaviour

Remarks on result:

other: CL: 1.22 to 1.48 mg/L

Details on results:

- Behavioural abnormalities: Affected fish lost schooling benaviour, swam near the tank bottom and were hypoactive. They were also underreactive to external stimuli, had increased respiration, were darkly coloured and lost equilibrium prior to death.

Validity criteria fulfilled:

not specified

Conclusions:

The 96-hour LC50 value for Pimephales promelas was determined to be 1.43 mg/L.

Executive summary:

Pimephales promelas were exposed to nerolidol for 96 hours. The LC50 was determined to be 1.43 mg/L and the EC50 for behavioural abnormalities was determined to be 1.34 mg/L. The guideline and GLP status of the study are unknown, however the study was well-reported and is reliable with restrictions (Klimisch 2).

Reference 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

secondary literature

Remarks:

Data were summarised from the US EPA Pesticides Ecotoxicity database and the original study is unretrievable.

Qualifier:

no guideline available

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Weight at study initiation (mean and range, SD): 0.27 g

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1.8 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 1.4 to 2.2 mg/L

Validity criteria fulfilled:

not specified

Conclusions:

The 96-hour LC50 for Oncorhynchus mykiss was determined to be 1.8 mg/L.

Executive summary:

The 96-hour LC50 for Oncorhynchus mykiss was determined to be 1.8 mg/L. The reliability of this study is not assignable (Klimisch 4) as the study was summarised from the US EPA Pesticides Ecotoxicity database and the original study is unretrievable.

Description of key information

The 96-hour LC50 value for Pimephales promelas exposed to nerolidol was determined to be 1.43 mg/L. Nerolidol is a suitable as a read-across substance to farnesol based on similarity of chemical structure and physicochemical properties.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1.43 mg/L

Additional information

Acute fish toxicity data are available for the read-across substance nerolidol. In a published study with Pimephales promelas, the 96 -hour LC50 was determined to be 1.43 mg/L (Brooke et al. 1984 -90). It is unknown if the study was conducted according to guideline or GLP, however sufficient details were reported for the test substance, organisms and test conditions. an appropriate number of test concentrations were used with adequate spacing factor, sufficient replicates were used, test concentrations were analytically verified, and a dose-response curve is observed with appropriate statistical significance. Therefore, the study is considered to be reliable with restrictions (Klimisch 2).

 

Read-across for this endpoint is appropriate as the test substance and the read across substance nerolidol are very similar in chemical structure, differing only by the interchange of a hydroxyl group and double bond on carbon positions 1 and 2, and very similar in physico-chemical properties. Acute toxicities to aquatic invertebrates (Daphnia) are in the same order of magnitude for both substances, and this was observed to be the most sensitive aquatic species in acute tests. Given the similarities in chemical and biological effects, nerolidol is considered to be a suitable read-across substance to fill this endpoint.

 

Since the nerolidol study is reliable and read-across is appropriate, this study is considered as key data for short-term toxicity to fish.

 

Supporting data is also available for the farnesol, in which the 96-hour LC50 for Oncorhynchus mykiss was determined to be 1.8 mg/L. The original study is referenced from the US EPA (1992) and could not be retrieved, therefore the reliability of the study could not be assigned (Klimisch 4). Although the reliability of this study cannot be assessed, the LC50 result is very similar to the LC50 from the key study with the read across substance, supporting the read across approach.