1,6-dibromohexane

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From April 1998 to October 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD, EPA, etc)

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dibromo-1,6-Hexane

IUPAC Name:

Dibromo-1,6-Hexane

Details on test material:

- Name of test material (as cited in study report): Dibromo-1,6-Hexane
- Substance type: colorless liquid
- Physical state: liquid
- Analytical purity: 99,45%
- Lot/batch No.: 3/97
- Other: insoluble at 20°C and volatile at room temperature

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

No data reported

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: This substance is insoluble, therefore, a solution of saturated test medium is prepared by agitation of 100 mg of dibromo-I,6-hexane with 1 liter of test medium, for 24 hours at 20 ° C. After this period of stirring, the solution decanted for 45 min, and the supernatant was recovered. It is then filtered under vacuum, using a filter of 0.45 µm.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna Straus (Cladocera, Crustacea),
- Strain: clone 5 or clone A
- Source: Breeding at Elf Atochem S.A. Centre d'application de Levallois
- Age at study initiation (mean and range, SD): Less than 24 hours
- Method of breeding: In a medium called Elendt M7 supplemented with food consists of algae microscopic Raphidocelis subcapitata.
- Feeding during test: No

ACCLIMATION: no acclimatation reported

QUARANTINE (wild caught): No quarantine reported

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

No post exposure observation reported

Test conditions

Hardness:

The sum of Ca and Mg ions in the dilution water is equal to 2.5 mmol/l. The reports of Ca/Mg ions and Na/K, respectively 4 and 10.

Test temperature:

Between 19 and 20°C

pH:

pH at 48h:
between 8.03 and 8.20

Dissolved oxygen:

O2 at 48 h (mg/L):
between 8.4 and 9.2

Nominal and measured concentrations:

Vol. solution saturated (%): 50, 25, 12.5, 6.3, 3.1, 1.6, 0.8
Measured conc. (T0) mg/l: 18.55, 9.23, 4.53, 2.20, 1.05, not detremined for 1.6% and 0.8% because of the detection limit (0.6 mg/L)
Measured conc. (T48) mg/l: not analysed for the 50% solution saturated, 8.90, 4.22, 2.08, 0.94, not detremined for 1.6% and 0.8% because of the detection limit (0.6 mg/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: falcon - penicillin type
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 120 mL nominal
- Aeration: No
- No. of organisms per vessel: 5 daphnia aged less than 24 hours
- No. of vessels per concentration (replicates): 4 replicates

TEST MEDIUM
* 11.76 g of CaCl2, 2H2O per liter of ultrapure water
* 4.93 g of MgS04, 7:20 per liter of ultrapure water
* 2.59 g of NaHCO3 per liter of ultrapure water
* 0.23 g of KCl per liter of ultrapure water.

Dilution water is obtained from 25 ml of each solution per liter of water and aerated to oxygen saturation.

OTHER TEST CONDITIONS
- Photoperiod: no photoperiod - exposed in the darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- mobility inhibition after 24 hours and 48 hours

TEST CONCENTRATIONS
- Spacing factor for test concentrations: geometric progression with a factor of 2
- Range finding study: yes in order to determine the concentrations of the definitive test - range of dilutions from the saturated stock solution between 0.1% to 100% (vol).
- Test concentrations:
* Vol. solution saturated (%): 50, 25, 12.5, 6.3, 3.1, 1.6, 0.8
* Measured conc. (T0) mg/l: 18.55, 9.23, 4.53, 2.20, 1.05, not detremined for 1.6% and 0.8% because of the detection limit (0.6 mg/L)
- Results used to determine the conditions for the definitive study: no reported in the report

Reference substance (positive control):

yes

Remarks:

Potatium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

1.7 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: from 1 to 2.3 mg/L

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 95% CL: from 0.68 to 1.7 mg/L

Details on results:

No additional data

Results with reference substance (positive control):

CE50-24h = 1.10 mg Potassium dichromate/l (same procedure as used for Dibromo-1,6-hexane)

Reported statistics and error estimates:

The EC50-24h and EC50-48h were calculated with measured initial concentrations by regression analysis using the Probit/log model.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity (inhibition of mobility) of Dibromo-1,6-hexane for Daphnia magna assessed according to the method C2 of the European Directive 92/69/CEE dispalys an EC50-24h of 1.7 mg/l and EC50-48h of 1.2 mg/l. Both EC values were calculated with measured initial concentrations by regression analysis using the Probit/log model. Under the conditions of this test, the substance appears to be toxic for invertebrates.

Executive summary:

The acute toxicity (inhibition of mobility) of Dibromo-1,6-hexane for Daphnia magna was assessed according to the method C2 of the European Directive 92/69/CEE. The study was carried out in compliance with the Principles of OECD Good Laboratory Practices.

Daphnids were exposed in a static test to a concentration range of 0,8 to 50 mg/l, forming a geometric progression with a factor of 2. The test was performed with 5 daphnids per vessel. Since Dibromo-1,6 -hexane is volatile, the test was perfonned using closed flasks as test vessels. In order to avoid volatilisation of Dibromo- 1,6 -hexane flasks were entirely filled with test solutions and closed with butyl rubber caps covered with PTFE.

For each exposure concentration, the percentage of immobilisation at 24 hours and 48 hours was recorded. The test concentrations of Dibromo-1,6 -hexane were measured by gas chromatography. EC50-24h and EC50-48h were calculated with measured initial concentrations by regression analysis using the Probit/log model.

* The EC50-24h was calculated to be 1.7 mg/l with 95 % confident interval ranging from 1 to 2,3 mg/l.

* The EC50-48h was calculated to be 1.2 mg/l with 95 % confident interval ranging from 0.68 to 1.7 mg/l.

The method was applied with respect to its quality criteria:

- Immobilisation in the control did not exceed 10 % at the end of the test ;

- Concentration of dissolved oxygen in the test vessels remained above 2 mg/l at the end of the test and pH did not vary by more than 1 unit ;

- The concentrations of the test substance have been maintained to within 80 % of the initial concentration throughout the duration of the test.