4-bromo-2,2-diphenylbutyric acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-09-16 to 2016-10-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: Guidance document on aquatic toxicity testing of difficult items and mixtures, OECD series on testing and assessment number 23, December 14, 2000

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-bromo-2,2-diphenylbutyric acid

EC Number:

253-648-3

EC Name:

4-bromo-2,2-diphenylbutyric acid

Cas Number:

37742-98-6

Molecular formula:

C16H15BrO2

IUPAC Name:

4-bromo-2,2-diphenylbutanoic acid

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): JNJ-1580774-AAA (T000835)
- Physical state: solid powder
- Appearance: slight beige

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: I16BB1136
- Expiration date of the lot/batch: 02 March 2017
- Purity: 99.3% (based on acid titration assay)
- Purity test date: 2016-04-27

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature
- Stability under test conditions: not indicated
- Solubility and stability of the test substance in the solvent/vehicle: 0.04 g/L in water

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Sampling method: samples were taken before the start of the test and after 72 hours from all test concentrations and from the control. A volume of 2.0 mL was taken from the control. The filter used for preparation of the SS was kept for possible analysis of the residue. At the end of the exposure period, the replicates with algae were pooled at each concentration before sampling. Reserve samples of 2.0 mL were taken from all test solutions for possible analysis.
- Sample storage conditions before analysis: stored in a freezer (< -15°C) until analysis.

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 a three-day period of magnetic stirring to ensure maximum dissolution of the test item in test medium. The resulting aqueous mixture was filtered through a 0.45 µm membrane filter (Whatman ME25 for the combined limit range-finding test and Whatman; RC55 for the final test) to remove the undissolved fraction of the test item. The filter was pre-conditioned with a small volume of test solution that was discarded. The obtained Saturated Solution (SS) was used as the highest test concentration. The lower test concentrations were prepared by subsequent dilutions of the SS in test medium. All final test solutions were clear and colourless.
After preparation, volumes of 50 mL were added to each replicate of the respective test concentration. Subsequently, 1 mL of an algal suspension was added to each replicate providing a cell density of 10^4 cells/mL.
- Controls: yes

Test organisms

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): In-house laboratory culture
- Method of cultivation: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21-24°C.

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): same as the test. 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 1 x 10^4 cells/mL. The pre-culture was maintained under the same conditions as used in the test. The cell density was measured immediately before use.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

24 mg CaCO3/L

Test temperature:

22-23°C

pH:

7.6 - 8.0

Dissolved oxygen:

not reported

Salinity:

not applicable

Nominal and measured concentrations:

nominal test concentrations final test: 10, 18, 32, 56 and 100% of a SS at 100 mg/L
measured test concentration final test t= 0 h: n.d., 2.78, 5.02, 8.81, 9.03, 15.6, 27.9 mg/L
measured test concentration final test t= 72h: n.d., 2.77, 5.02, 8.80, 9.01, 15.6, 21.6 mg/L

The four lowest test concentrations remained stable during the test period (100% of initial at the end of the test). The highest test concentration slightly decreased to 77% of initial at the end of the test.

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks
- Type (delete if not applicable): capped vessels
- Material, size, headspace, fill volume: 100 mL all-glass flasks filled with 50 mL test solution
- Aeration: no
- Type of flow-through (e.g. peristaltic or proportional diluter): no flow-through system applied
- Renewal rate of test solution (frequency/flow rate): no renewal
- Initial cells density: 10,000 cells/mL
- Control end cells density: 156.3 x 10,000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M2 according to the OECD 201 guideline, formulated using Milli-RO water
- Culture medium different from test medium: no
- Intervals of water quality measurement: temperature measured continuously, pH at the beginning and the end of the test.

OTHER TEST CONDITIONS
- Sterile test conditions: no information
- Adjustment of pH: none
- Photoperiod: continuous illumination
- Light intensity and quality: 60 to 120 μE/m2/s when measured in the photosynthetically effective wavelength range of 400 to 700 nm, using TLD-lamps.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: At the beginning, cells were counted using a microscope and a counting chamber.
- effect calculated parameters: specific growth rate and yield

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8

- Range finding study
- Test concentrations: 1.00, 10 and 100 % of the SS prepared at 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

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

13 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: CL 95%: 12-14 mg/L

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

5 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:
- EC50 (yield) = 7.4 mg T000835 /L
- EC10 (growth rate) = 6.1 mg T000835 /L (95% C.L. 4.8-7.1 mg/L).
- EC10 (yield) = 2.7 mg T000835 /L (95% C.L. 1.6-3.6 mg/L).
- NOEC (yield) = <2.8 mg T000835 /L

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 72-h EC50 (growth rate) = 1.0 mg/L (95% confidence interval ranging from 0.97 to 1.0 mg/L)
The historical ranges for growth rate inhibition lie between 0.82 and 2.6 mg/L. The observed 72h-ERC50 for the algal culture tested corresponds with this range.

Reported statistics and error estimates:

Calculation of ECx values was based on weibit analysis using linear maximum likelihood regression with the percentages of growth rate inhibition and the percentages of yield inhibition versus the logarithms of the corresponding geometric mean concentrations of the test item.
The calculations were performed with ToxRat Professional v. 3.2.1 (ToxRat Solutions® GmbH, Germany)

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

A 72-h growth inhibition test with the unicellular green alga Pseudokirchneriella subcapitata was performed with the test substance T000835 according to the OECD guideline 201.
Under the test conditions, T000835 inhibited growth rate of this fresh water algae species significantly at a mean concentrations of 8.8 mg/L and higher. The 72-h ECr50 was determined to be 13 mg/L.
The results of the test can be considered reliable without restrictions.