Docosane

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study initiation date: May 9, 2008. Observation: June 28, 2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of relevant results.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

Principles of method if other than guideline:

Based on the solubility of the test substance, the WAF (Water Accommodated Fraction) was formulated for test concentrations.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations:
The concentrations of total organic carbon (TOC) were determined in the samples of test solutions.

- Sampling method:
10 ml samples of test media were taken from the control and test material vessels at the end beginning and the end of the first and the third 24 hours of the 96-hours period.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Preliminary test:
The preliminary test was conducted with the limit test concentration of 1000 mg/l as WAF (nominal concentration). A concurrent water control group was performed in parallel.
Based on the solubility of the test substance, the WAF (Water Accommodated Fraction) was formulated for test concentrations by combining the test material and dilution water on weight to volume basis.

Definitive test:
According to the results of the preliminary test, the definitive test was conducted with the limit test concentration of 1000 mg/L as WAF (nominal concentration). A concurrent water control group was performed in parallel.

Test concentration preparation:
The WAF (Water Accommodated Fractions) was formulated for the test concentration by combining the test material and dilution water on a weight to volume basis. The test material/dilution water combinations, contained in 10 liter jars (diameter: 22cm, height: 40 cm), were stirred at 23 ± 2°C for 24 hours with a magnetic force stirrer at 300 rpm and a vortex was formed which represented a slight dimple at the water surface. Following the mixing period, the formulation was allowed to settle for 2 hours and then the water phases containing the WAF were removed by mid-depth siphoning.
A wide bore glass tube covered at one end with parafilm was submerged into the mixing vessel, sealed end down, to a depth about 5 cm from the bottom of the container. A length of Tygon tubing was inserted into the glass tube and pushed through the parafilm seal. Then, a small amount of the WAF was removed and checked microscopically; micro-dispersions were not detected. The WAF was removed by siphon, the first 75-100 ml of aqueous phases being discarded. Insoluble materials were not taken up during siphoning. The aqueous phase or WAF were collected and used for the toxicity test.

Exposure concentration and grouping:
The concentration of 1000 mg/l as WAF was selected. Accurately weighed 10 g of test substance was put into 10 liters of test water. Stirring only
commenced after all the test material had been added. During the first hour, the mixing rate was checked periodically to ensure the prescribed vortex height was maintained. The vortex formation was periodically re-checked throughout the test duration.
WAF was prepared approximately 26 hours prior to the start of the test and each test media renewal period, and then split to the test vessel. Group of ten zebra fish were exposed to the test media. At intervals of 24 hours (24, 48 and 72 hours) the fish were transferred to tanks containing freshly prepared test media.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebra fish
- Strain: Brachydanio rerio
- Source: Qianmin Fishery of Yuhong District in Shenyang
- Age at study initiation (mean and range, SD): Juvenile
- Length at study initiation (length definition, mean, range and SD): 2-3 cm
- Feeding during test: daily until 24 hours before the test was started.


ACCLIMATION
- Acclimation period: Fish were held in the laboratory for 12 days to acclimatize to the test conditions.
- Acclimation conditions (same as test or not): Fish were held in water of the quality to be used in the test and under the following conditions:
Light: natural photoperiod, 12-16 hours
Temperature: 23 ± 2°C
Oxygen concentration: at least 80% of ASV
- Health during acclimation (any mortality observed): There was no death or any sign of disease during the acclimatization period.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

The fish were were observed for toxic signs and deaths at 3, 6, 24, 48, 72 and 96 hours after initial exposure. The criterion for death was no opercula movement during a 15 second period of observation.

Hardness:

250 ± 25 mg/l as CaCO3.

Test temperature:

22.4 - 23.7°C

pH:

7.94 - 8.16

Dissolved oxygen:

7.7 - 8.8 mg/l

Salinity:

Ca/Mg was approximately 4:1.

Nominal and measured concentrations:

The definitive test was conducted with the limit concentration of 1000 mg/L as WAF (nominal concentration).

Details on test conditions:

TEST SYSTEM
- Test vessel: glass tanks (30 cm x 30 cm x 30 cm) filled with about 9L test media.
- Renewal rate of test solution (frequency/flow rate): Renewal of test solutions every 24 hours.
- No. of organisms per vessel:10.
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
The dilution water used was reconstituted water (ISO 6341-1982)
(a) Calcium chloride solution: Dissolve 147.00 g CaCl2.2H2O in deionised water; make up to 5 litres with deionised water.
(b) Magnesium sulphate solution: Dissolve 61.625 g MgSO4.7H2O in deionised water; make up to 5 lites with deionised water.
(c) Sodium bicarbonate solution: Dissolve 32.375 g NaHCO3 in deionised water; make up to 5 litres with deionised water.
(d) Potassium chloride solution: Dissolve 2.875 g KCl in deionised water; make up to 5 litres withdeionised water.

One liter each of solutions (a) to (d) was mixed and the total volume was made up to 100 liters with deionised water. The dilution water was then aerated until oxygen saturation was achieved, and it was then stored for about two days without further aeration before use. The pH was 7.8±0.2, hardness was about 250+25 mg/l (as CaC03), Ca/Mg was about 4: 1.

OTHER TEST CONDITIONS
- Photoperiod: Natural light, 12-16 hours.
-Oxygen concentration: Not less than 60% of ASV during the test period.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The fish were observed daily. The abnormality and deaths were recorded at 3, 6, 24, 48, 72 and 96 hours after exposure. The criterion for death was no opercula movement during a 15 second period of observation.

Physicochemical Measurements:
The pH value, dissolved oxygen and temperature were measured at the beginning of the test and 24-hour intervals during the 96-hour exposure period in both control and test media. The total water hardness and alkalinity were measured at the beginning of the test.

TEST CONCENTRATIONS
- Results used to determine the conditions for the definitive study: Based on the results of a preliminary test at 1000 mg/l WAF, where the fish treated with the test media showed no abnormalities or deaths during the test period.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LL50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: Determined test concentration was 0.09 mg/l as TOC.

Details on results:

Physicochemical measurements:
The determined results of pH value, dissolved oxygen and temperature were 7.94-8.16, 7.7-8.8mg/L and 22.4-23.TC, respectively. The allowed range of the pH value is 6.0-8.5, the temperature is 21-25°C, and dissolved oxygen is at least 60 percent of the air saturation value throughout the test.

Toxic signs:
There was no significant difference between the control and the test group.
The fish treated with the test media showed no abnormalities or deaths during the test period.

Verification of Test Concentrations:
The results showed that there was no significant difference between the control and test material samples (due to the poorly water solubility of the test substance), and there was no significant difference between fresh and the expired solutions. Because the test substance was added to the test water at 1000 mg/L, the test concentration expressed with TOC was 0.09 mg/L (i.e mean of TOC 1000 mg/l - TOC ck).

Approximate LL50:
According to the results of the test, the determined test concentration was 0.09 mg/L as TOC, and the 96-hours LLso to zebra fish (Brachydanio rerio) was greater than 1000 mg/L as WAF (0.09 mg/L as TOC).

Results with reference substance (positive control):

Not applicable.

Sublethal observations / clinical signs:

Cumulative Mortality:

Nominal concentration (mg/l)	Initial population	Time (hr)	Cumulative mortality	Abnormalities
Control	10	3	0	No observed toxic signs
		6	0
		24	0
		48	0
		72	0
		96	0
1000	10	3	0	No observed toxic signs
		6	0
		24	0
		48	0
		72	0
		96	0

 

Validity criteria fulfilled:

yes

Conclusions:

According to the results of the test, the determined test concentration was 0.09 mg/L as TOC, and the 96-hours LLso to zebra fish (Brachydanio rerio) was greater than 1000 mg/L as WAF (0.09 mg/L as TOC).

Executive summary:

Introduction.

An acute toxicity study of 'Distillates (Fischer - Tropsch), heavy, C18 -50 - branched, cyclic and linear' was conducted with the freshwater to zebra fish (Brachydanio rerio).

Methods.

Based on the results of the preliminary test, a definitive test was conducted using a limit test concentration of l000 mg/L as WAF (nominal concentration). Groups of ten zebra fish were exposed to the test media. A concurrent water control group was performed in parallel. The test was performed with a semi-static water renewal system. The pH value, dissolved oxygen and temperature were determined at the beginning of the test and at 24-hour intervals during the 96-hours exposure period. Water hardness and total alkalinity were measured at the beginning of the test in the control tank. The fish were observed daily. The abnormalities or deaths were recorded at 3, 6, 24, 48, 72 and 96 hours after exposure. During the 96-hours exposure period, no abnormalities or deaths were observed in either the control or exposure fish.

Samples of test media were taken from the control and test material vessel at the beginning and the end of the first and the third 24 hours of the 96-hours period, concentrations of total organic carbon (TOe) were determined in the samples.

Results.

The results showed that there was no significant difference between the control and test material samples (due to the poorly water solubility of the test substance), and there was no significant difference between fresh and the expired solutions. Because the test

substance was added to the test water at 1000 mg/L, the test concentration expressed with TOC was 0.09 mg/L (i.e. mean of TOC 1000 mg/L - TOCck).

According to the results of the test, the determined test concentration was 0.09 mg/L as TOC, and the 96-hours LLso to zebra fish (Brachydanio rerio) was greater than 1000 mg/L as WAF (0.09 mg/L as TOC).

Description of key information

The 96 -hour LL₅₀ for GTL Base Oil Distillates was determined to be >1000 mg/L (Brachydanio rerio).

This data is used for read across to Docosane.

Additional information

The short-term toxicity of GTL Base Oil Distillates to freshwater fish Brachydanio rerio (zebra fish) has been determined; the test was conducted in accordance with OECD Test Guideline 203.

Water-accommodated fractions (WAFs) of the sample were prepared in jars, by stirring for approximately 24 hours. The contents of the vessels were left to stand for 2 hours before drawing off the aqueous phase – the WAF – for testing. Semi-static exposures were then carried out.

The test was conducted in accordance with GLP and the TOC of test media were analysed for stability and exposure concentration. Total Organic Carbon (TOC) analysis of the freshly prepared test preparations showed amount of carbon present within the 1000 mg/l loading rate WAF test vessels to range from 1.71 mg C/l to 1.79 mg C/l. TOC analysis of the old test media showed amount of carbon present to range from 1.56 mg C/l to 1.64 mg C/l. There was no significant difference in TOC content between control and exposure vessels. This was expected by the authors due to the low water solubility of the test substance. 

The test results, expressed as the LL₅₀ value, showed that GTL Base Oil Distillates was not hazardous to fish at a loading rate of 1000 mg/l WAFs.