2-bromobutane

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:

16 October 2016 - 11 November 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Test guideline 2

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:

2-bromobutane

EC Number:

201-140-7

EC Name:

2-bromobutane

Cas Number:

78-76-2

Molecular formula:

C4H9Br

IUPAC Name:

2-bromobutane

Test material form:

liquid

Details on test material:

- Name of test material (as cited in the report): JNJ-47961173-AAA
- Physical state: Liquid
- Colour: Colourless

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: M15IB3251
- Expiration date of the lot/batch:07 April 2017 (retest date)
- Purity: 100% (based on gas chromatographic purity)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions: stable

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Sampling method: samples for possible analysis were taken form all test concentrations and the control at t=0 and t=48h. 16.0 mL of volume was taken from the approximate centre of the test vessels.
- Sample storage conditions before analysis: samples were analysed on the day of sampling. All samples were transferred to vials containing 4 ml of n-Hexane (SupraSolv Batch: I793071534; Merck, Darmstadt, Germany) immediately after sampling.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Preparation of test solutions started with a loading rate of 100 mg/L applying two days of magnetic stirring at room temperature to ensure maximum dissolution of the test item in test medium. The resulting aqueous mixture was left to stabilize for approximately 1 to 1.5 hours. The Saturated Solution (SS) was subsequently siphoned off and used as the highest test concentration. The lower test concentrations were prepared by subsequent dilutions of the SS in test medium.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): final test solutions were clear and colourless

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water-flea
- Source: in-house laboratory culture with a known history
- Age at study initiation (mean and range, SD): < 24 h (from parental daphnids of more than 2 weeks old, maximum age 4 weeks)
- Method of breeding: 250 newborn daphnids (i.e. less than 3 days old) are placed into 5 liters of medium in an all-glass culture vessel. Medium is M7. After 7 days of cultivation half of the medium is renewed twice a week.
- Feeding during cultivation: fresh water algae, daily
- Feeding during test: no

ACCLIMATION
- Acclimation period: not relevant

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

180 mg/L as CaCO3 pH: 7.7 ± 0.3

Test temperature:

20-21°C

pH:

At t= 0h: 7.9 - 8.2
At t= 48h: 7.3-7.6

Dissolved oxygen:

At t= 0h: 8.4-8.8
At t= 48h: 8.0-8.4

Salinity:

not relevant

Conductivity:

not relevant

Nominal and measured concentrations:

Nominal concentrations: control, 1.0, 10 and 100% of a Saturated solution (SS) prepared at 100 mg/L.
Combined limit/range-finding test 1:
Measured concentrations (mg/L) at t=0h: n.d., 0.120, 1.23, 14.7
Measured concentrations (mg/L) at t=48h: n.d., n.d., 0.164, 2.27

The analysis of the samples taken during the first combined limit/range-finding test showed a relatively strong decrease of the concentrations measured. Information obtained after performance of this study indicated that the test item is volatile. In addition to the absence of biological effects during the test, it was decided to repeat the combined limit/range-finding test with air-tightly closed vessels and minimum headspace as to minimize loss of test item due to volatility and to confirm the biological results.

Combined limit/range-finding test 2:
Measured concentrations (mg/L) at t=0h: n.d., 0.112, 1.09, 11.3
Measured concentrations (mg/L) at t=48h: n.d., 0.056, 0.567, 4.58

Samples taken from all test concentrations were analysed. The initial concentrations measured were 0.11, 1.1 and 11 mg/L in 1.0, 10 and 100% of the SS, respectively. At the end of the exposure period, the measured concentrations had decreased to 40-52% of the initial concentrations.

Details on test conditions:

TEST SYSTEM
- Test vessel: beaker
- Material, size, headspace, fill volume: 50 mL, glass container, air-tight closed with no headspace
- Aeration: not during the test
- Type of flow-through (e.g. peristaltic or proportional diluter): no flow-through
- Renewal rate of test solution (frequency/flow rate):no renewal, static system
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Test medium: adjusted ISO medium

OTHER TEST CONDITIONS
- Photoperiod: 16h light daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility was defined as those organisms which are not able to swim within 15 seconds after gentle agitation of the test container and was monitored after 24 and 48 hours of continuous treatment with the test substance.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Range finding study
- Test concentrations: 1.0, 10 and 100% of a SS prepared at a loading rate of 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 7.2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: none
- Other adverse effects control: no
- Abnormal responses: none
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: substance is volatile
- During the second combined limit/range-finding test no significant immobility was observed in the control or in any of the test concentrations throughout the test duration. However, five daphnids were found trapped at the test medium surface in one of the control vessels at the end of the test. Four of these daphnids were mobile after re-immersion

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50/LC50: 48h-EC50 = 0.58 mg/L. the sensitivity of the daphnia was within the range determined with the historical data collected at Charles River Laboratories.

Reported statistics and error estimates:

The 24h- and 48h-EC50 could not be determined because the observed effects were below 50%.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of 2-bromobutane to Daphnia magna was determined in a 48-hour static test according to the OECD guideline 202.
The 48h-EC50 was above the limit of solubility of the test item in test medium, i.e. exceeded an average exposure concentration of 7.2 mg/L as measured in a saturated solution prepared at a loading rate of 100 mg/L. The results of the test can be considered reliable without restriction.