4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]diphthalic anhydride

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

Study period:

October to November 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Deviations were recorded during the study but they are not thought to have had a significant impact on results.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

See 'any other information on materials and methods'

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch number: CT20201015
Re-test date: 10th September 2022
Storage conditions: store in a cool dry place

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

4,4’-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]diphthalic anhydride (6FDA) was characterised as poorly soluble and therefore was prepared by Water Accommodated Fractions (WAFs). Test material stocks were individually prepared by weighing out an appropriate amount of test material, adding US EPA culture medium and stirring for approximately 20h. The stocks were then left to settle for 1h and the mid column of the stock was siphoned off, taking care to avoid siphoning any undissolved material.

Test organisms (species):

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

Details on test organisms:

The P. subcapitata strain used was 278/4 and originated from SAMS Limited.

Pre-cultures in the exponential growth phase were prepared from stock laboratory cultures by inoculating autoclaved freshwater at 120 °C for 15 minutes with nutrient medium (3N-BBM+V) 2 to 4 days before test commencement. They were then incubated at approximately 21 +/- 2 °C under constant illumination to be used as the inoculum source for subsequent toxicity tests.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Not specified

Test temperature:

21 – 24°C, controlled at +/- 2°C

pH:

7.5 +/- 0.1

Dissolved oxygen:

Not specified

Salinity:

Not specified

Conductivity:

Not specified

Nominal and measured concentrations:

Nominal Concentration: 1000, 1800, 3200, 5600 and 10000 mg/L

Details on test conditions:

The test was conducted in 100 ml borosilicate glass conical flasks, to which 50 mL of test medium which was nutrient enriched (with 3N-BBM+V) was added. At pre 0h or 0h, the pH of the culture medium was adjusted if required, by adding 1M HCl, or NaOH to give a pH of 7.5 +/- 0.1.

Each treatment was inoculated with cells from the pre-cultures in the exponential growth phase to give an initial cell density of approximately 5 x 103 – 104 cells per millilitre for P. subcapitata. Following inoculation, all flasks were loosely covered with aluminium foil caps and mounted on an orbital shaker. The illumination consisted of 40 W cool white LED light which was mounted at a distance of approximately 50 cm directly above the test area. Light intensity values were measured daily during the test. The controlled temperature test room temperature was 21 – 24 +/- 2 °C

A range-finding test was conducted over 72h to determine the approximate concentrations at which growth rate effects were observed. The range-finding test employed four concentrations 1000, 100, 10 and 1 mg/L with one replicate per concentration; plus, four controls. The pH of the stocks and culture medium was 7.5 +/- 0.1. Where they were out-with, they were adjusted using 1M NaOH (100, 1000, 1800, 3200 mg/L). However, an excessive amount of adjustment media was required to adjust the 5600 mg/L concentration, and the Study Director made the decision to cease adjustment as it would have required too much NaOH. The 10000 mg/L was unadjusted also.

The definitive test was conducted over 72h at concentrations determined from the results of the range-finding test. The definitive test employed five concentrations with three replicates per concentration; plus, six controls. In the definitive test, counts of algal cell numbers were carried out daily by fluorometer measurements. Three readings were performed on each test vessel.

Reference substance (positive control):

yes

Remarks:

A reference test with potassium dichromate was conducted to check the test procedure and sensitivity. The concentration range for P. subcapitata is 0.32, 1.0, 1.8 and 3.2 mg/L.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4 400 mg/L

95% CI:

>= 4 320 - <= 4 400

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

The results for the reference substance are valid with an EC50 of 0.661-1.719 mg/L

Validity criteria fulfilled:

yes

Conclusions:

In the definitive test 4,4’-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]diphthalic anhydride (6FDA) exhibited a 72h EC(r)50 value of 4400 mg/L (WAFs) to the freshwater phytoplankton P. subcapitata in the aqueous phase.

Executive summary:

A short-term toxicity study to determine the aquatic toxicity of 6FDA to freshwater unicellular algae (pseudokirchneriella subcapitata) was determined by a GLP compliant study performed in accordance with the OECD 201 test guideline.

In order to determine the concentrations to be used in the definitive test, a range finding study was performed over 72 hours to determine the appropriate concentrations at which growth rate effects were observed.  6FDA was characterised as poorly water soluble and was therefore prepared by water accomodated fractions (WAF). 

The concentration range used in the definitive test was 1000, 1800, 3200, 5600 and 10000 mg/L.

The 72-hour EC50 for 6FDA was 4400 mg/L

Description of key information

A short-term toxicity study to determine the aquatic toxicity of 6FDA to freshwater unicellular algae (pseudokirchneriella subcapitata) was determined by a GLP compliant study performed in accordance with the OECD 201 test guideline.

In order to determine the concentrations to be used in the definitive test, a range finding study was performed over 72 hours to determine the appropriate concentrations at which growth rate effects were observed.  6FDA was characterised as poorly water soluble and was therefore prepared by water accomodated fractions (WAF). 

The concentration range used in the definitive test was 1000, 1800, 3200, 5600 and 10000 mg/L.

The 72-hour EC50 for 6FDA was 4400 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

4 400 mg/L

EC10 or NOEC for freshwater algae:

3 200 mg/L