2-fluoro-6-trifluoromethylpyridine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Substance ID: F6TF
Lot #: AF0460
Purity: 99.5%

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all
- Sampling method: high performance liquid chromatography method; As undissolved material was observed in the test vessels all samples were analysed both pre and post-centrifugation. At the start of the test, samples were taken of each excess test solution, immediately after filling the test vessels. At the end of the test, each blank solution was sampled and analysed in the same manner, immediately on opening.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances): This study was run with a culture medium control and a solvent control together with nominal test substance concentrations of 2.2,4.4, 8.8, 18, 36 and 72 mg/L. The test substance was volatile and was not readily dissolved in water, therefore stock solutions in dimethylformamide were prepared. Each test solution was prepared, in completely full, glass stoppered volumetric flasks, to minimise volatilisation, by the addition of an aliquot of the relevant stock solution to sterile culture medium. These introductions were made, after equalising additions of dimethylformamide, where applicable, such that the solvent control and all test concentrations contained 0.10 mL/L of dimethylformamide. The control solution, similarly treated, consisted of culture medium only. All additions were made sub-surface and gradually by microlitre syringe, into solutions gently stirred by magnetic follower. The stirring duration was minimised due to the volatile nature of the test substance. After preparation, a visual assessment of the test solutions showed both controls and the nominal 2.2 mg/L test concentration to be clear and colourless. All higher nominal test concentrations contained increasing densities of white particles in homogeneous stirred suspension. Some small, colourless globules were also seen in the 18, 36 and 72 mg/L test solutions. However subsequent analysis showed that the test solution concentrations were within the required range. Using aseptic techniques, 60 mL volumes of the appropriate test solution were dispensed to each test and blank vessel, with the remainder of the test solutions being used for physical and chemical analyses.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: unicellular green alga Selenastrum capricornutum
- Strain: Strain ATCC 22662
- Source (laboratory, culture collection): ATCC
- Age of inoculum (at test initiation): A 3 day old culture of the alga in the exponential growth phase was used as inoculum for the test.
- Method of cultivation: The culture was grown in the medium, and under the environmental conditions, described for the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 ± 2°C

pH:

Test start: 8.6
Test end: 8.8 - 9.3

Nominal and measured concentrations:

Nominal concentrations: 2.2, 4.4, 8.8, 18, 36 and 72 mg/L
Measured concentrations: starting post-centrifugation 2.3, 4.5, 8.6, 17, 34 and 64 mg/L

Starting post-centrifugation measured concentrations ranged from 89 to 105% of nominal.
The study end post-centrifugation measured concentrations in the blanks ranged from 88 to 98% of nominal values.

Details on test conditions:

- Test vessel: borosilicate glass bottles of 50 mL nominal capacity filled completely (approximately 60 mL of test solution) with airtight, PTFE septa and aluminium caps.
- Temperature: incubated at 24 ± 2ºC with orbital shaking
- No. of vessels per concentration (replicates): 2 test substance, 2 solvent control, 4 culture medium control
- Test concentrations: culture medium control, solvent control, 2.2, 4.4, 8.8, 18, 36 and 72 mg/L test substance

- Exponential growth in the control (for algal test): yes
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: After preparation, a visual assessment of the test solutions showed both controls and the nominal 2.2 mg/L test concentration to be clear and colourless. All higher nominal test concentrations contained increasing densities of white particles in homogeneous stirred suspension. Some small, colourless globules were also seen in the 18, 36 and 72 mg/L test solutions. However subsequent analysis showed that the test solution concentrations were within the required range.

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

> 72 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

other: EbC50

Effect conc.:

> 72 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

36 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

72 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth rate and biomass

Reported statistics and error estimates:

The area under the growth curve (days 0 to 3) was calculated for each replicate culture, according to the formula given in the OECD Guideline. These areas were examined by one-way analysis of variance. Dunnett's procedure was used to identify significant differences (P=0.05) from the solvent control.

Validity criteria fulfilled:

yes

Conclusions:

72-hour EbC50 > 72 mg/L
72-hour ErC50 > 72 mg/L

Executive summary:

The toxicity of the test substance to the green algae, Selenastrum capricornutum, was determined in a 72-hour, static toxicity test. Test vessels were filled to the top and sealed to prevent loss of the test substance. The vessels were incubated at approximately 24°C with orbital shaking. The following endpoints were calculated:

72-hour ErC₅₀ > 72 mg/L

72-hour EbC₅₀ > 72 mg/L

Description of key information

Based on nominal concentrations because mean measured concentrations were within 80-120% of nominal:
72-hour ErC50 > 72 mg/L 
72-hour EbC50 > 72 mg/L  

Key value for chemical safety assessment

EC50 for freshwater algae:

72 mg/L