Potassium 2-(3-trifluoromethoxy-1,1,2,2,3,3-hexafluoropropoxy)-2,3,3,3-tetrafluoropropionate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

19 Apr 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Test guideline 2

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

MV31-K-salt

IUPAC Name:

MV31-K-salt

Details on test material:

- Name of test material (as cited in study report): MV31 K-salt, Potassiumperfluoromethoxypropoxypropionate
- Substance type: Pure active substance
- Physical state: solid, grey granules
- Analytical purity: ca. 88 %
- Storage condition of test material: darkness at approximately 20 °C in a fume cupboard

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: test solutions were made by adding test substance gravimetrically to 16 mL synthetic sewage in 200 mL activated sludge suspension. The final volume was brought to 500 mL with deionized water.
- Controls: negative control, postive control (3,5-dichlorophenol)
- Chemical name of vehicle: none

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source of inoculum/activated sludge: Domestic sewage treatment plant, Kriftel, Germany
- Preparation of inoculum for exposure: After a settling period of approximately 30 minutes the supematant liquid phase was decanted and crude particles were removed by a sieve. After resuspension with mineral medium (per OECD301), settling down and decantation, the sludge was concentrated by centrifugation. Before resuspension, an aliquot of concentrated sludge was used for dry weight determination. 300 g concentrated sludge was then resuspended in 3 liter of mineral medium, and 150 mL synthetic sewage (per OECD209) added. The suspension was aerated until use.
- Initial biomass concentration: 2.83 g dry weight/L

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

21.3 - 21.6 °C

pH:

7.2 - 7.5

Nominal and measured concentrations:

Nominal only, 0 (negative control), 10 mg/L, 32 mg/L, 100 mg/L, 320 mg/L and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Incubation in 500-mL Erlenmeyer flasks. Measurement in 250-ml Karlsruher flasks.
- Aeration: Continuous aeration during the incubation period.
- Biomass loading rate: 1.13 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Sludge was washed and suspended in mineral medium prepared according to OECD301. Dilution of test solutions was in deionized water with a conductance of < 1 µS/cm. Test flasks were assembled with 16 mL synthetic sewage, 200 mL sludge suspension, test (dry) or reference substance (in solution), and deionized water to make up 500 mL total. The reference substance was 3,5-dichlorophenol prepared as per OECD209. Test flasks were incubated in darkness under aeraration for the exposure period and then decanted for measurement.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Dissolved oxygen concentration after 3 hours exposure. DO concentration was measured continuously by oxygen probe and plotted with a chart recorder. The linear section of the curve was used to calculate respiration rate.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: No dose response, EC50 not calculated

Results with reference substance (positive control):

- Results with reference substance valid? yes, EC50 was 5.03 mg/L by probit analysis

Reported statistics and error estimates:

The control (blank) flasks had a difference of 14%. The test substance did not show a consistent dose response and showed only a small (11%) effect at the highest concentration tested (Table 1). The EC50 of the test substance could not be calculated.

Any other information on results incl. tables

Table 1, Respiration rates and inhibition of respiration
Test material	Concentration (mg/L)	Respiration rate (mg 02/L/h)	Inhibition (%)
Control 1	0	37.5	─
Control 2	0	43.0	─
Mean, control 1 + 2	0	40.3	(13% difference)
MV31 K-salt	10	36.0	11
MV31 K-salt	32	40.0	1
MV31 K-salt	100	36.0	11
MV31 K-salt	320	39.6	2
MV31 K-salt	1000	36.0	11
3,5-Dichlorophenol	3.2	22.8	43
3,5-Dichlorophenol	10	16.8	58
3,5-Dichlorophenol	32	2.4	94

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Control respiration rates within 15%, ref substance EC50 in range 5-30 mg/L

Conclusions:

The EC50 of MV31-K-salt to activated sludge is >1000 mg/L (EU method C.11)

Executive summary:

Toxicity of MV31-K-salt to activated sludge was assessed according to EU method C.11. Difference between duplicate controls was 13%. Respiration rate did not show a clear dose-response with MV31-K-salt, with percent inhibition at the highest and lowest concentrations (10 mg/L and 1000 mg/L) 11% in both cases. The EC50 could not be calculated but is >1000 mg/L.

The study followed an accepted guideline and was compliant with GLP criteria. It is considered reliable without restrictions. It is suitable for Risk Assessment, Classification & Labelling, and PBT Analysis.