Acetamide, N-(3',4'-dichloro-5-fluoro[1,1'-biphenyl]-2-yl)-

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N-{3',4'-dichloro-5-fluoro-[1,1'-biphenyl]-2-yl}acetamide

EC Number:

620-313-1

Cas Number:

877179-03-8

Molecular formula:

C14H10Cl2FNO

IUPAC Name:

N-{3',4'-dichloro-5-fluoro-[1,1'-biphenyl]-2-yl}acetamide

Sampling and analysis

Analytical monitoring:

yes

Remarks:

HPLC analysis

Details on sampling:

SAMPLING SCHEDULE:
Control: at 72 hours
Test concentration/s: 0.85, 4.1 and 20 mg/L and 20 mg/L without algae at 0 and 72 hours

STORAGE
All solutions were stored in the dark at 4 °C.

Test solutions

Vehicle:

no

Details on test solutions:

A stock solution was prepared to give the desired series of test concentrations. 101 mg of the test item were added to 1 litres of dilution water, treated for 1 h in an ultrasonic bath and stirred for 24 h on a magnetic stirrer. Undissolved particles of the test item were removed by filtration using a folded filter with a pore size of 7 - 12 µm and an aseptic filter Sartobran sterile capsules with a pore size of 0.45 µm + 0.2 µm. The pH was measured to be 7.8.
To produce the different test item concentrations appropriate amounts of the stock solution were diluted with dilution water to a volume of 100 mL and 0.401 mL of the algal inoculum was added to each replicate resulting in a final cell density of 5000 cells/mL. For each test item concentration and the control 3 replicates were prepared. All flasks were sealed with cotton stoppers.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Source: Strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany).
Maintenance and Acclimatisation: Exponentially growing stock cultures were maintained in the test facility under constant temperature conditions (21 - 24 °C with a maximum fluctuation of +/- 2 °C) at a light intensity in the range 60 to 120 µE x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The growth medium was renewed once a week.
Preparation of pre-cultures: Pre cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different growth medium.
Test cultures : The algal inocula for the test were taken from an exponentially growing pre culture and were mixed with the growth medium to make up to a final cell density of about 5000 cells per millilitre in the test medium.

Study design

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

21 – 24 °C

pH:

7.8 - 8.1

Nominal and measured concentrations:

0.39, 0.85, 1.9, 4.1, 9.1 and 20 mg/L (nominal)

Details on test conditions:

APPARATUS
Analytical balance
pH meter
Shaking incubator
Particle counter
Various glass materials: Erlenmeyer flasks, volumetric flasks, beakers, pipettes etc.

EXPOSURE CONDITIONS
Test vessels : 300 mL Erlenmeyer flasks with cotton stoppers test volume: 100 mL
Culturing apparatus: shaking incubator in which a temperature in the range 21 °C to 24 °C was maintained at +/- 2 °C, and continuous uniform illumination was provided in the spectral range 400 to 700 nm. Temperature was measured and recorded daily.
Light intensity: A light intensity ranging from 60 to 120 µE x m-2 x s-1, or an equivalent range of 4000 to 8000 lux, was measured. The light intensity was checked before the start of the study.
Cell density measurements: Cell densities were measured in a particle counter by aliquots from each test flask, which were not replaced.
Experimental design: 6 test concentrations plus 1 control; 3 replicates per concentration, 3 replicates per control; Initial cell density in the test cultures approximately 5000 cells per millilitre. Additionally highest test concentration without algae.
Method of administration: stock solution (100 mg/L)

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.19 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.13 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.085 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.19 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Reported statistics and error estimates:

All calculations were carried out using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10). For the calculations all algae counts were divided by a factor of 10000.

Any other information on results incl. tables

NOEC and LOEC of both, yield and growth rate, were determined by a multisampling comparison (according to Williams / Dunnett`s Multiple Sequential t-Test Procedure / Student t-Test Procedure).

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

The cell density in the control cultures increased by a factor of at least 16 within 72 h. The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures did not exceed 7 %.

Conclusions:

A study was performed to assess the adverse effects of test item on the growth rate of the planktonic freshwater algal species Desmodesmus subspicatus showing an EC50 value of 0.19 mg/l after 72 hours.

Executive summary:

A study was performed to assess the adverse effects of test substance on the growth rate (= rate of increase in cell density with time) and the yield (= biomass at time t minus initial biomass) of the planktonic freshwater algal species Desmodesmus subspicatus (former name:Scenedesmus subspicatus) over several generations.

The study was conducted in accordance with Commission Regulation (EC) No 761/2009 amending Regulation No 440/2008, Method C.3, which is equivalent to OECD Guideline for Testing of Chemicals No. 201 (2006).

Exponentially growing algal cells were exposed for a period of 72 hours to a range of concentrations, nominally 0.39, 0.85, 1.9, 4.1, 9.1 and 20 mg/L of test substance dissolved in dilution wate

The cell densities were measured at 24 hour intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. The following values were determined:

E_rC 50 (0-72 h):           0.19 mg/l

E_rC 10 (0-72 h):          0.13 mg/l

NOEC [r] (t_α 0.05):       0.085 mg/l

LOEC [r] (t_α 0.05):       0.19 mg/l