Propanenitrile, 2,3,3,3-tetrafluoro-2-(trifluoromethyl)-

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

21 May - 11 Jun, 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material: 3M N.B # us278898.001-096
- Expiration date of the lot/batch: 10/30/2021
- Purity: 97.7%
- Physical state: White solid

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature
- Stability under storage conditions: Stable

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 10, 100, 1000 mg/L
- Analytical samples were taken from parallel sludge free test solutions made at the same concentration as spiked test solutiuons. The 100 mg/L and 1000 mg/L analytical solutions were diluted 10 and 100 times with water respectivley, before chemical analysis.
- Sample storage conditions before analysis: Samples were stored and refrigerated at 2-8° C if not analyzed within 24 hours.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION:
- Method: 5 g/L of the test substance stock solution was prepared by dissolving 5000.4 mg test substance in 1L ultra-pure water. One, 10, or 100 mL of stock solution was added to make test samples. Test solutions included 16 mL of synthetic sludge, water to 250 mL, and 250 mL activated sludge suspension.
- Controls: blank control, abiotic control, nitrification inhibitor control.

Test organisms (species):

activated sludge

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Zhuyuan Domestic Sludge Treatment Plant in Shanghai China.
- Preparation of inoculum for exposure: Upon arrival at the laboratory, the sludge was washed with three times with an isotonic solution (0.85% NaCl (w/v)) by centrifugation for 20 minutes (4000 rpm, 4 C). During each individual wash, the supernatant was decanted and discarded. In order to calculate dry weight, a small portion of the washed sludge was then weighed and dried via moisture meter at 105 C for 1 hour. The washed sludge was aerated until use, and that a sample was taken to assess dry weight. The dry weight of the sludge was up to 6.01% of the gross weight. Sludge concentrations were calculated and diluted on the test day to obtain the required sludge solids concentrations of 3 g/L. Suspension was then aerated until use. Final concentrations of activated sludge in the test medium was 1.5 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

pH:

6.21-7.83

Dissolved oxygen:

5.45-8.49 mg/L

Nominal and measured concentrations:

Nominal: 0 (blank control, nitrification control, abiotic control), 10, 100, 1000 mg/L
Measured: 11.7, 107, 1130 mg/L (concentrations at start of measurement in 10, 100, and 1000 mg/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: 2000 mL bottles
- Type: open during aeration
- Aeration: Yes
- No. of vessels per concentration (replicates): The 10 and 100 mg/L solutions were tested with 1 replicate and 1000 mg/L solution tested in triplicate with and without nitrification inhibitor.
- No. of vessels per control (replicates): 2 replicates for each control group (Blank control and Nitrification group control)
- No. of vessels per reference substance group (replicates): 1 replicate per test solution (4 solutions)
- No. of vessels per abiotic control (replicates): One replicate
- Sludge concentration: 3.0 g/L
- Nutrients provided for bacteria: synthetic sewage per OECD 209
- Nitrification inhibitor used: N-allylthiourea
- Biomass loading rate: 1.5 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Ultra pure water produced by Milipore MilliQ A10

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Details on termination of incubation: After the 3-hour exposure, a sample was transferred to a 270 mL glass BOD bottle. A dissolved oxygen meter was inserted into the bottle and stirring started.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Dissolved oxygen concentration. For each exposure, dissolved oxygen depletion and time interval were correlated and the slope of the regression line was calculated as the respiration rate.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2x

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

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

Details on results:

- Blank controls oxygen uptake rate: 29.70 and 28.35 mg/( h*g SS)
- Coefficient of variation uptake rate in control replicates: 3.30%
- Inhibition for 1000 mg/L concentration: 4.01, 4.67, and 7.11
- Effect on nitrification: The nitrification respiration values were less than 5% of total respiration of the blank control group and the corresponding concentration of test groups. Therefore, nitrification respiration was insignificant and no nitrification occured during the test.

Results with reference substance (positive control):

- Results with reference substance valid: Yes
- EC50: 3 hour EC50=16.5 mg/L (95% CI 14.9-18.0 mg/L). The EC50 was within the 5 to 25 mg/L range considered acceptable for the test.

Reported statistics and error estimates:

The EC50 was calculated with a Linear interpolation method, and utilized a t-test to indicate significant differences between the blank controls and limit test group. The statistics were run with the Toxcalc v5.0.32.

Table 1.Oxygen consumption rates and percentage inhibition values of test substances in range finding experiment.

Test Group	Group	Upper Limit DO (mg/)	Lower limit DO (mg/L)	∆t (min)	R (mg/L h)	Rs	IT(%)
FBlank(mg/L)	C1	6.76	2.06	6.33	44.55	29.70	-
	C2	6.89	2.05	6.83	42.52	28.35	-
FR(mg/L)	7.8	6.46	2.05	7.00	37.88	25.20	13.17
	12.6	6.99	2.06	11.00	26.89	17.93	38.23
	20	7.34	4.50	10.00	17.04	11.36	60.86
	32	8.49	7.25	10.00	7.44	4.96	82.91
FT(mg/L)	10	6.19	2.06	6.00	41.30	27.53	5.41
	100	6.54	2.08	6.50	41.17	27.45	5.71
	1000	6.34	2.03	6.17	41.91	27.94	4.01
	1000	6.34	2.06	6.17	41.62	27.75	4.67
	1000	5.45	2.07	5.00	40.56	27.04	7.11
FA(mg/L)	1000	8.42	8.40	10.00	0.12	-	-
FNB(mg/L)	C1	6.90	2.10	6.83	42.17	28.11	-
	C2	6.90	2.04	7.00	41.66	27.77	-
FN(mg/L)	10	6.87	2.03	7.33	39.62	26.41	5.76
	100	6.78	2.03	7.17	39.75	26.50	5.45
	1000	6.91	2.01	7.33	40.11	26.74	4.59
	1000	6.84	2.02	7.17	40.33	26.89	4.07
	1000	6.58	2.06	6.50	41.72	27.81	0.75

F_Blank: FBlank control group

F_R: Reference control

F_T: Test substance group

F_A: Abiotic control

F_NB: Nitrification control group

F_N: Nitrification group

C: Control          

Validity criteria fulfilled:

yes

Remarks:

Control oxygen uptake rate > 20 mg O2/gram sludge/hour (29.7 and 28.35 mg O2/(h.g SS)); coeff. of variation <30% for control replicates (3.30%); ref. substance EC50 in range 5-25 mg/L (16.4 mg/L).

Conclusions:

3 hour EC50 of >1000 mg/L (OECD 209) in activated sludge for respiration inhibition.

Executive summary:

The toxicity of heptafluoroisopropylamide to activated sludge was assessed according to the OECD 209 guideline in a range finding test conducted at 10, 100, 1000 mg/L. The validity criteria were met based on an acceptable level of oxygen uptake in control samples, acceptable variation among control replicates and a typical level of inhibition with the positive control. No effects were observed without or without nitrification inhibitor N-allylthiourea. The 3-hour EC50 (respiration) of heptafluoroisopropylamide to activated sludge is >1000 mg/L. The study followed an internation standard method and is GLP compliant. Therefore the study is deemed reliable without restrictions and can be utilized to calculate a PNEC for STP.

Description of key information

3 hour EC50 of >1000 mg/L (OECD 209) in activated sludge for respiration inhibition.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The toxicity of heptafluoroisopropylamide to activated sludge was assessed according to the OECD 209 guideline in a range finding test conducted at 10, 100, 1000 mg/L. The validity criteria were met based on an acceptable level of oxygen uptake in control samples, acceptable variation among control replicates and a typical level of inhibition with the positive control. No effects were observed without or without nitrification inhibitor N-allylthiourea. The 3-hour EC50 (respiration) of heptafluoroisopropylamide to activated sludge is >1000 mg/L. The study followed an internation standard method and is GLP compliant. Therefore the study is deemed reliable without restrictions and can be utilized to calculate a PNEC for STP.