4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]diphenol; bisphenol AF

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04 July 2017 to 10 January 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted in accordance with international guidelines and in accordance with GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Version / remarks:

July, 2010

Deviations:

yes

Remarks:

Refer to "principles of method if other than guidance"

Principles of method if other than guideline:

Guideline Deviation: The OECD Guideline 209 (July 22nd, 2010) recommends five replicates per test concentration and six replicates for the blank control in a full test with five concentrations. According to the Question-and-Answer Document by the German Federal Environment Agency on the new OECD Guideline 209 "Activated Sludge, Respiration Inhibition Test (Carbon and ammonium Oxidation)" (Version: 02.03.2012) a minimum preparation of a full test with five concentrations are three replicates per test concentration and six replicates for the blank control. In our test design we followed the recommendation of the German Federal Environment Agency and prepared three replicates for each test concentration and six replicates for the blank control.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test item was added directly to the test vessels.
- Eluate: N/A
- Differential loading: 1000, 312.5, 97.65, 30.5 and 9.54 mg/L concentrations were used int he main test(3 replicates per test concentration)
- Controls: 6 control vessels were tested
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): N/A
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): N/A
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): None observed

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant Staufener Bucht was used as test system. The treatment plant has a capacity of 140 000 inhabitant equivalents and clarifies predominantly domestic wastewater. Sampling date of activated sludge was 18 July 2017 (range-finder test) and 17 October 2017 (full test). The activated sludge was kept aerated until use at test temperature. Dry solid of the activated sludge was determined as 3.7 g/L (limit test) and 4.0 g/L (full test) by weight measurements before and after drying at 105°C (mean of triplicate measurements). The activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in chlorine-free tap water. Before using, the activated sludge was diluted to 3 g/L dry solids with chlorine-free tap water, in order to obtain a final concentration of 1.5 g/L dry solids in the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

Standard guideline duration

Post exposure observation period:

Not applicable

Test temperature:

The temperature range within the test duration was between 20.9 and 21.9°C.

pH:

The pH in all test vessels at the beginning of the test vessels was 7.3.
The pH in the reference vessels was 7.3.
The pH in the blank vessels was 7.3.

Nominal and measured concentrations:

Nominal Concentrations: 0, 9.54, 30.5, 97.65, 312.5 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 - 300 ml BOD bottles with adapter for oxygen electrode, Germany
- Aeration: Yes
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): N/A
- No. of vessels per abiotic control (replicates): N/A
- Sludge concentration (weight of dry solids per volume): Before using, the activated sludge was diluted to 3 g/L dry solids with chlorine-free tap water, in order to obtain a final concentration of 1.5 g/L dry solids in the test.
- Nutrients provided for bacteria: Yes
- Nitrification inhibitor used (delete if not applicable): none

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Chlorine free tap water
- Particulate matter: Not reported

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: N/A
- Light intensity: Not reported
- Details on termination of incubation: After 3 h the aeration of the first vessel was shut off and the respiration rate was measured in a BOD-bottle with an oxygen electrode while mixing with a magnetic stirrer.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Justification for using fewer concentrations than requested by guideline: Not applicable
- Range finding study
- Test concentrations: 0, 10, 100 and 1,000 mg/L
- Results used to determine the conditions for the definitive study: Yes

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

126.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks on result:

other: 95% CIL:

Remarks:

36.372 - 427.057 mg/L)

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

47.87 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks on result:

other: 95% CL:

Remarks:

16.646 - 137.663 mg/L)

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: No
- Effect concentrations exceeding solubility of substance in test medium: No
- Adsorption (e.g. of test material to the walls of the test container): Not assessed
- Blank controls oxygen uptake rate: >20 mg O2/g/h
- Coefficient of variation of oxygen uptake rate in control replicates: <30 %

Results with reference substance (positive control):

In the full test the EC50 of 3,5-dichlorphenol was estimated as 6.2 mg/l (Appendix III) and was therefore within the acceptable range of 2 to 25 mg/l.

Reported statistics and error estimates:

EC50, EC10, LOEC and NOEC and confidence limits (CL) were estimted by ToxRat Professional Version 3.2.1, © ToxRat Solutions GmbH. The ECx calculation was performed with the ToxRat software by probit analysis using linear max. likelihood regression and calculated from the slope of the curve.

Respiration Rate of Activated Sludge after Application of Test and Reference Item in the Full Test

 

Vessel Number	Concentration	Consumption Rate [mg/(l*h)]	Consumption Rate [mg/g sludge*h)]	Inhibition [%]
1	Blank 1	42.7	28.5	-
2	Blank 2	39.1	26.1	-
3	Blank 3	29.8	19.8	-
22	Blank 4	31.9	21.3	-
23	Blank 5	19.7	13.1	-
24	Blank 6	25.2	16.8	-
			Mean value: 20.9 Standard deviation: 5.7 CoV: 27.3%
7	Test 9.54 mg/L 1	19.2	12.8	39
8	Test 9.54 mg/L 2	36.2	24.2	-15
9	Test 9.54 mg/L 3	45.8	30.6	-46
10	Test 30.5 mg/L 1	37.2	24.8	-18
11	Test 30.5 mg/L 2	33.1	22.1	-5
12	Test 30.5 mg/L 3	37.7	25.1	-20
13	Test 97.65 mg/L 1	21.6	14.4	31
14	Test 97.65 mg/L 2	17.3	11.5	45
15	Test 97.65 mg/L 3	20.2	13.4	36
16	Test 312.5 mg/L 1	7.0	4.6	78
17	Test 312.5 mg/L 2	4.1	2.7	87
18	Test 312.5 mg/L 3	4.1	2.7	87
19	Test 1000 mg/L 1	3.6	2.4	89
20	Test 1000 mg/L 2	2.2	1.4	93
21	Test 1000 mg/L 3	2.4	1.6	92
4	Reference 1	23.3	15.5	26
5	Reference 2	14.6	9.8	53
6	Reference 3	7.4	5	76

Validity criteria fulfilled:

yes

Conclusions:

The 3h EC50 for heterotrophic respiration was 126.8 mg/L (95%-CL: 36.372 - 427,057 mg/L). The 3h EC10 for heterotrophic respiration was 47.870 mg/L (95%-CL: 16.646 - 137.663 mg/L)

Executive summary:

An OECD 209 Activated sludge inhibition test (2010) was conducted with the test item. This was to assess the inhibition effect of different concentrations of test item to micro-organisms of activated sludge by measuring the respiration rate after 3h contact time. The test met all guideline validity criteria.

The results for the inhibition of the total respiration of activated sludge were:

EC₅₀= 126.8 mg/L (95%-CL: 36.372 – 427,057 mg/L)

EC₁₀= 47.870 mg/L (95%-CL: 16.646 – 137.663 mg/L)

LOEC = 97.65 mg/L

NOEC≥30.5 mg/L

Description of key information

3h EC50 = 126.8 mg/L; 3h EC10 = 47.87 mg/L; OECD 209; Anon., 2018

Key value for chemical safety assessment

EC50 for microorganisms:

126.8 mg/L

EC10 or NOEC for microorganisms:

47.87 mg/L

Additional information

An OECD 209 Activated sludge inhibition test (2010) was conducted with the test item. This was to assess the inhibition effect of different concentrations of test item to micro-organisms of activated sludge by measuring the respiration rate after 3h contact time. The test met all guideline validity criteria.

The results for the inhibition of the total respiration of activated sludge were:

EC50= 126.8 mg/L (95%-CL: 36.372 – 427,057 mg/L)

EC10= 47.870 mg/L (95%-CL: 16.646 – 137.663 mg/L)

LOEC = 97.65 mg/L

NOEC = ≥30.5 mg/L