4-ethylphenol

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 February 1985 - 22 Febrauary 1985

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference Type:

review article or handbook

Title:

Unnamed

Year:

1986

Report date:

1985

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

4-ethylphenol

EC Number:

204-598-6

EC Name:

4-ethylphenol

Cas Number:

123-07-9

Molecular formula:

C8H10O

IUPAC Name:

4-ethylphenol

Test material form:

solid

Specific details on test material used for the study:

Source: Aldrich Chemicals Co.
Purity: 99%

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

All test exposure chambers were sampled at approximately mid-depth at 0, 24, 48, 72 and 96 hr in all exposure chambers. All samples were analyzed immediately or adequately preserved for later analysis.

Test solutions

Vehicle:

no

Details on test solutions:

Nominal concentrations [mg/L]: 0, 10.5, 16.1, 24.8, 38.2, 58.9
Test chemicals were prepared for proportional dilution. Diluted stocks were prepared in 18.9 L stainless steel carbonation vessels. Lake Superior water was filtered through sand and a cotton fiber filter. Lake Superior water plus the toxicant were added to the vessels and stirred or blended vigorously.
When the pH of the stock was outside of the 7 to 8 range, the pH was adjusted to approximately that of Lake Superior water (pH 7 .8) with either NaOH or concentrated HCl.

Test organisms

Test organisms (species):

Pimephales promelas

Details on test organisms:

Fathead minnows used in the tests were cultured in the U.S. EPA Environmental Research Laboratory-Duluth and the University of Wisconsin-Superior campus.
Adults were held at 25° C in flowing water with a 16-hr light-con­trolled photoperiod and fed frozen adult brine shrimp (Artemia sp.). They were provided with asbestos pipes (cut in half longitudinally) as spawning substrates. The naturally spawned and fertilized embryos became attached to the underside of the spawning substrates. The substrates, with intact embryos, were removed daily and placed in another 25 C bath. where hatching occurred; however, the spawning substrates were removed just prior to hatching at the UW­Superior culture unit, then placed in a rearing bath.
Fish that had been reared in flow-through tanks in the lab's culture units were used. Larvae were fed 40 to 48-hr old brine shrimp nauplii (iio-Marine Research, Inc., Hawthorne, CA} in excess two times daily (once on week-end days). Embryos and larvae were cultured in water from the same source as used in the exposures to the test chemicals.
Fish that were approximately 26 to 37-days old were used in the toxicity tests. Only groups of fish having healthy appearance and no history of unusual thermal exposure or abnormally high mortality rate were used for toxicant exposure. Test fish were not fed 24 hr before or during a test.

Study design

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test conditions

Hardness:

52.5 ±1.22 mg/L CaCO3

Test temperature:

24.3 ±0.27 °C

pH:

7.72 ±0,05

Dissolved oxygen:

7.0 ±0,37 mg/L

Nominal and measured concentrations:

Nominal concentrations [mg/L]: 0, 10.5, 16.1, 24.8, 38.2, 58.9
meas. 02/18/85 [mg/L]: <2.0, 7.9, 11.5, 19.3, 29.9, 45.1
meas. 02/19/85 [mg/L]: <2.0, 9.5, 14.9, 21.1, 31.6, 45.9
meas. 02/20/85 [mg/L]: <2.0, 9.4, 13.4, 20.4, 31.8, 49.2
meas. 02/21/85 [mg/L]: <2.0, 9.8, 14.0, 21.9, 34.9, 51.1
meas. 02/22/85 [mg/L]: <2.0, 9.2, 13.1, 20.8, 32.0, 48.2

Average [mg/L]: 2.0, 9.16, 13.4, 20.7, 32.0, 47.9
Cor. average [mg/L]: 2.0, 9.17, 13.4, 20.7, 32.1, 47.9

Details on test conditions:

Prior to initiating a test, prospective test fish were "pooled" if reared in more than one tank. At the start of a test, individuals were removed from the "common pool" of fish with a net and distributed at random among the exposure chambers. The tests were initiated by adding 20 fish per treatment and control. Fish loading did not exceed 0.5 g/L per day in flow-through systems.
Death was the major test endpoint. The number of dead fish was noted every 24 hr after the beginning of a test, at which time they were also removed.
Observations of fish behavior and toxic signs were made at 2-8, 24, 48, 72 and 96 hr.
Upon test termination, individual control fish were weighed (wet weight) and measured (standard length). Mean legth of fish was 23.5 mm, and he mean weight was 0.204 g/L. The loading was 2.04 g/L.
Five water quality parameters were routinely measured for each test. They were: water temperature, dissolved oxygen, total hardness, total alkalinity and pH.

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

10.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Effect concentrations 2

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

10.4 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

behaviour

Reported statistics and error estimates:

The estimated LC50 and EC50 with correspond­ing 95% confidence intervals were calculated using the corrected average of the analyzed tank concentrations and the Trimmed Spearman-Karber Method

Any other information on results incl. tables

Sublethal observations / clinical signs:

Biological growth appeared in the tanks at 72 hours. Affected fish swam in a corkscrew/spiral pattern with half the fish located at the surface and half located at the bottom of the aquaria. They were hyperactive and over-reactive to external stimuli, had increased respiration, and rigid musculature. They were also hemorrhagic and deformed, had convulsions, and lost equilibrium prior to death.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

-dissolved oxygen concentration ≥60% of the air saturation value -mortality in the control <10% -analytical measurement of concentrations

Conclusions:

The 96 hours LC 50 was determined as 10.4 mg/L

Executive summary:

The toxicity of the test item against Fathead minnows was determined in a 96-h acute toxicity test similar to OECD 203. 

The 96 hours LC 50 was determined as 10.4 mg/L.