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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:
1995
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was given a reliability rating of 1 because it followed a standard test guideline, which describes a procedure to evaluate this endpoint, and the results were reviewed for reliability and assessed as valid. The study was also conducted under GLP.
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
An equilibration trial was performed to determine the time required for the components of the test substance to achieve maximum aqueous solubility. Five glass aspirators were each filled with 22L of main dechlorinated water, leaving a small headspace of air. The test substance was added to four of the vessels at a loading rate of 1000 mg/L, and the contents of the fifth aspirator served as the control. All five vessels were then sealed, and stirred as vigorously as possible without creating a dispersion in the sealed vessels, which contained a small headspace of air to permit stirring. After nominal stirring periods of 24, 48, 72, 96and 198 hours, the WAF solutions were allowed to settle for 1-3 hours, after which a sample of the aqueous layer was extracted and analyzed by GC/FID. The results of the equilibration study showed that equilibrium between the test substance components and the aqueous phase at a loading of 1 g/L was reached in about 72-96 hours.
Vehicle:
no
Details on test solutions:
For purposes of the fish toxicity test, individual treatment solutions were prepared as Water Accommodated Fractions (WAFs). This included adding test substance to 15-16 liter glass aspirator bottles, which contained laboratory dilution water, that was filtered (15 um) through
activated charcoal. The WAF was stirred for 93-96 hours as vigorously as possible without creating a dispersion in the sealed vessels, which contained a small headspace of air to permit stirring. After mixing, the WAFs were allowed to settle for one hour, after which the aqueous phase was removed for testing.

A limit test was conducted using one replicate each for a control WAF, and at a 1000 mg/L WAF loading concentration. The loading rate was based on the results of a range-finding study, details of which were not included in the definitive study report. Each replicate system contained seven fish in completely filled (11L of WAF or control water) glass aspirator bottles that were sealed with glass plates to exclude air. After 24, 48 and 72 hours exposure any dead or immobilized fish were removed and surviving fish were transferred to previously prepared WAFs. After 96 hrs exposure, the fish were observed again and the test was terminated. Samples of each batch of WAF were taken at the time of preparation and at the end of the period of use 24 hours later for GC/FID analysis, D.O. and pH. Temperature was measured hourly in a vessel adjacent to the test vessels throughout the test.
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
Fish were obtained from Hartford Trout Farm, Brompton Regis, Somerset U.K. and acclimated to the test conditions for a minimum of seven days before use. A sample of seven of the fish used in the test had a mean length of 4.6 cm and a mean weight of 0.96 g. The fish were not fed in the 24 hr preceding the test, nor during the test.
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Hardness:
Water hardness was 244 to 268mg/L as CaCO3.
Test temperature:
Test temperature was 15.3-15.9 Deg C.
pH:
The pH ranged from 7.2 to 7.5 during the study.
Dissolved oxygen:
Dissolved oxygen was 8.9 to 9.8 mg/L.
Salinity:
freshwater
Nominal and measured concentrations:
WAF concentration (mg/L) of dissolved hydrocarbon (derived from test substance) as determined by GC/FID. Specific hydrocarbon isomers were not identified. Analytical results are based on mass attributable to the test material. Control concentration was <0.05 mg/L at all sampling intervals identified above.

Time 1000 mg/L WAF
0 hr 0.31
24 hr new 0.35
24 hr old 0.17
48 hr new 0.28
48 hr old 0.19
72 hr new 0.35
72 hr old 0.20
96 hr old 0.26
Mean 0.26
Details on test conditions:
Artificial light cycle was 16 hours on and 8 hours dark.
Reference substance (positive control):
no
Key result
Duration:
96 h
Dose descriptor:
LL0
Effect conc.:
>= 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
No mortality observed during the 96 hour test.

96-hour LL0 = 1000 mg/L
96 hour LL50 >1000 mg/L

An LC50 based upon measured values was not calculated.

This value is representative of acute aquatic fish toxicity for those C14-C20 (high aromatics) aliphatic category members having an initial minimum boiling point range of 264C. Since the hydrocarbon constituents for these category members with boiling point values greater than 264 deg C do not show adequate water solubility in equilibrated aqueous solutions, acute aquatic toxicity effects are not expected at the 1000 mg/L maximum loading concentration investigated in this study
Reported statistics and error estimates:
No statistics performed.
Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%), as measured by mortality to rainbow trout (Oncorhynchus mykiss) was evaluated in freshwater. Under the conditions of this study, Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%) did not produce acute lethal toxicity to Oncorhynchus mykiss at 1000 mg/l, based on nominal loading of the test substance in water.
Executive summary:

The acute toxicity of Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%), as measured by mortality to rainbow trout (Oncorhynchus mykiss) was evaluated in freshwater. Under the conditions of this study, Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%) did not produce acute lethal toxicity to Oncorhynchus mykiss at 1000 mg/l, based on nominal loading of the test substance in water.

Description of key information

The acute toxicity of Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%), as measured by mortality to rainbow trout (Oncorhynchus mykiss) was evaluated in freshwater. Under the conditions of this study, Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%) did not produce acute lethal toxicity to Oncorhynchus mykiss at 1000 mg/l, based on nominal loading of the test substance in water. These data are used as read-across data to hydrocarbons, C14 -C18, n-alkanes, isoalkanes, cyclics, aromatics (2 -30%).

In another study, the acute toxicity of Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%), as measured by mortality to rainbow trout (Oncorhynchus mykiss) was evaluated in freshwater. Under the conditions of this study, Hydrocarbons, C16-C20, n-alkanes, isoalkanes, cyclics, aromatics (2-30%) did not produce acute lethal toxicity to Oncorhynchus mykiss at 1000 mg/l, based on nominal loading of the test substance in water. These data are used as read-across data to hydrocarbons, C14 -C18, n-alkanes, isoalkanes, cyclics, aromatics (2 -30%).

Key value for chemical safety assessment

Additional information

Water accommodated fractions of hydrocarbons, C16 -C20, n-alkanes, isoalkanes, cyclics, aromatics (2 -30%) did not cause acute toxicity to fish at a nominal loading of 1000 mg/l with rainbow trout, Oncorhynchus mykiss. These data are used as read-across data to hydrocarbons, C14 -C18, n-alkanes, isoalkanes, cyclics, aromatics (2 -30%).