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Sediment toxicity

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Administrative data

sediment toxicity: short-term
Type of information:
experimental study
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study acceptable for assessment

Data source

Reference Type:
Simultaneous Evaluation of the Acute Effects on Seven Aquatic Species
Ewell WS, Gorsuch JW, Kringle RO, Robillard KA and|Spiegel RC
Bibliographic source:
Environmental Toxicology and Chemistry Vol. 5, pp. 831-840.

Materials and methods

Test guideline
other: EPA-600/3-75-009
Principles of method if other than guideline:
U.S. Environmental Protection Agency. 1975. Methods for Acute Toxicity Tests with Fish, macroinverte-brates and Amphibians.
Ecology Series. EPA-600/3-75-009. Duluth. MN.
The method evaluates the potential of substance to cause acute aquatic effects in seven juvenile aquatic species simultaneously.
GLP compliance:

Test material

Details on test material:
purity was reagent grade

Sampling and analysis

Details on sampling:
The maximum concentration used in these bioassays was 100 mg/L. Chemicals known to be readily soluble at 100 mg/L were added directly to the
diluent water in each aquarium in the appropriate amounts to give nominal concentrations of 100, 10, 1 and 0.1 mg/L. Test chemical concentrations
were not analysed.

Test organisms

Test organisms (species):
Lumbriculus variegatus
Details on test organisms:
The method simultaneously exposes seven species from five phyla. All test organisms were acclimated to the control diluent water in the breeding/rearing tanks. Food was withheld for the 24 h preceding start of the test. Juveniles of each species, as uniform in size as possible, were collected from
the colonies. Ten juvenile organisms of each species were routinely exposed to the test chemical in each treatment. Stratified randomisation was
accomplished by proportioning out no more than 20% of any one species into an aquarium at any one time. Biological loading was kept below
0.5 gram wet weight per liter of test solution. The average wet weight for a randomly chosen set of minnows was determined at the start of the test.
The other six species were not weighed. The minnows and snails were placed in the test vessels. The remaining five species were segregated in
welded stainless steel, 55-mesh wirecloth baskets (5.5 cm in diameter * 7.5 cm in depth).
Each basket was suspended from a 1-rpm motor-driven mechanism that raised and lowered the baskets in the water column. A stainless steel band, slotted every 0.5 cm, facilitated the positioning of the baskets so that the submerged volumes changed from one-third to two-thirds during each
cycle. The baskets were spaced around the test vessel rim so that they did not interfere with each other. One-half of the volume of the submerged
basket was exchanged with the main tank volume every minute.

Study design

Study type:
laboratory study
Test type:
Water media type:
Type of sediment:
not specified
Exposure duration
96 h
Exposure phase:
total exposure duration

Test conditions

Test temperature:
20 +/- 1°C
6.5 - 8.5
Dissolved oxygen:
dissolved oxygen was determined, but no values specified
Nominal and measured concentrations:
Nominal concentration: 0.1, 1.0, 10 and 100 mg/l

Results and discussion

Effect concentrations
Dose descriptor:
Effect conc.:
3.2 other: mg/l
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
Details on results:
The LC50 values were estimated by an interpolation method using a Computer program written for aquatic toxicity studies
Dead organisms were removed when observed. A test organism was considered dead if it appeared motionless and exhibited no response
to gentle prodding. If more than one-half of the population of a species exposed in any treatment was determined to be dead, additional aquaria
containing lower concentrations of test solution were set up. All seven species were exposed to each dose level. At any time during the test when all 10 organisms of a species were considered dead, these biological Parameters were determined and recorded.

Applicant's summary and conclusion

Executive summary:

Sediment toxicity of thymol to segmented worm (Lumbriculus variegatus) were performed together with seven single-species according to the Methods of US-EPA from 1975. In this multispecies test, a 96 h LC50 of 3.2 mg/l were obtained (Ewell, 1986).