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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
13 April 2017 - 11 May 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Deviations:
no
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
1,1,1,2,3,3-hexafluoro-2-(heptafluoropropoxy)-3-[(trifluorovinyl)oxy]propane
EC Number:
216-703-2
EC Name:
1,1,1,2,3,3-hexafluoro-2-(heptafluoropropoxy)-3-[(trifluorovinyl)oxy]propane
Cas Number:
1644-11-7
Molecular formula:
C8F16O2
IUPAC Name:
1,1,1,2,2,3,3-heptafluoro-3-({1,1,1,2,3,3-hexafluoro-3-[(1,2,2-trifluoroethenyl)oxy]propan-2-yl}oxy)propane
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 116B2018
- Physical state: clear and colorless liquid
- Analytical purity: 96.3%
- Expiration date of the lot/batch: 31 August 2018
- Purity test date: 15 Nov 2016

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature container flushed with nitrogen

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge from the 'Waterschap Aa en Maas' municipal sewage treatment plant ('s-Hertogenbosch, The Netherlands), receiving predominantly domestic waste. Suspended solids concentration was 4.0 g/L from the plant.
- Storage conditions: Continuous aeration until use.
- Storage length: Not reported ("freshly obtained")
- Preparation of inoculum for exposure: Sludge allowed to settle 33 minutes and liquid decanted for use as inoculum.
- Pretreatment: None
- Concentration of sludge: 10 mL/L mineral medium
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
20 mg/L
Based on:
other: organic carbon
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium as per method TG310, water was purified by reverse osmosis and subsequently passed over activated carbon and ion-exchange cartridges (MIllipore, Bedford, MA, USA)
- Solubilising agent (type and concentration if used): none
- Test temperature: 20 - 21 °C
- pH: 7.8 at beginning of test
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: septum-sealed glass bottles
- Number of culture flasks/concentration: triplicate bottles for days 8, 14, and 21, five bottles for day 28
- Method used to create aerobic conditions: Test was performed in sealed bottles with a headspace:medium ration of 1:2 to provide a reservoir of oxygen adequate for the duration of the exposure.
- Measuring equipment: Equipment as detailed
- Test performed in closed vessels due to significant volatility of test substance: Yes
- Details of trap for CO2 and volatile organics if used: Closed bottle test. Evolved CO2 was forced into the test medium by the addition of 1 mL 7M NaOH.

SAMPLING
- Sampling frequency: Days 8, 14, 21, and 28
- Sampling method: bottles sacrificed and analyzed as detailed
- Sterility check if applicable: None

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, sampled at each time point
- Abiotic sterile control: yes, inoculum free sample additionally treated with 1 mL/L of a 10 g/L solution of HgCl2 (sampled on day 28 only)
- Toxicity control: Yes, reference substance and PPVE-2, each at 20 mg C/L (sampled on Days 8 and 14 only)
- Positive control: Sampled on Days 8 and 14 only
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
ca. 0
Sampling time:
28 d
Remarks on result:
other: Not significantly different than blanks
Details on results:
Average inorganic carbon (IC) concentration in blanks (Table 1) on Day 28 was 1.623 mg/L (SD, 0.178 mg/L). Average IC concentration in PPVE-2 bottles (Table 2) on Day 28 was 1.718 mg/L (SD, 0.129 mg/L). The two averages are not significantly different according to Student's T-test (P = 0.36). Therefore, there was no significant biodegradation of PPVE-2 (statistics calculated for this study summary)

The reference substance was 71% degraded by day 14 (Table 3). Inorganic carbon concentrations in positive control and toxicity control (Table 3) were not significantly different on Day 8 (P = 0.87) or Day 14 (P = 0.91). Therefore, there was no significant effect of PPVE-2 on degradation in this study (statistics calculated for this summary with assumption that all IC in toxicity control was from degradation of the reference substance).

Any other information on results incl. tables

  Table 1, Individual concentrations of inorganic carbon (IC) in mg/L for the blank control during the biodegradation test.

Day

Bottle 1

Bottle 2

Bottle 3

Bottle 4

Bottle 5

Mean

Std. dev.

8

1.310

1.195

1.205

1.237

0.064

14

1.610

2.097

1.910

1.872

0.246

21

1.931

1.950

1.860

1.914

0.047

28

1.926

1.521

1.551

1.485

1.633

1.623

0.178

 

  Table 2, Individual concentrations of inorganic carbon (IC) in mg/L for PPVE-2 during the biodegradation test.

Day

Bottle 1

Bottle 2

Bottle 3

Bottle 4

Bottle 5

Mean

Std. dev.

Percent degradation

8

1.276

1.278

1.342

1.299

0.038

0

14

1.577

3.076

3.516

2.723

1.017

4

21

1.906

1.914

1.995

1.938

0.049

0

28

1.726

1.919

1.565

1.718

1.663

1.718

0.129

0

 

 

Table 3, Individual concentrations of inorganic carbon (IC) in mg/L for positive control (R), toxicity control (T), and abiotic control (C) during the biodegradation test.

Day

Bottle 1

Bottle 2

Bottle 3

Bottle 4

Bottle 5

Mean

Std. dev.

Percent degradation

R8

11.64

13.16

11.21

12

1.025

54

R14

16.70

15.69

15.18

13.84

18.97

16.08

1.918

71

T8

12.82

14.33

9.658

12.27

2.384

28

T14

15.32

16.54

21.62

13.14

12.69

15.86

3.584

35

A28

0.9115

0.8278

1.051

0.7894

0.6796

0.8519

0.1391

-4

 

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
< 3 mg/L inorganic carbon in blanks at end of test, reference substance > 60% degraded by day 14
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
PPVE-2 is not readily biodegradable
Executive summary:

Ready biodegradability of PPVE-2 was studied in a test done according to OECD TG310. PPVE-2, sodium benzoate (reference substance), or both chemicals (toxicity control) were introduced to test bottles at 20 mg/L theoretical organic carbon (ThOC). Bottles also contained mineral medium inoculated with activated sludge from a predominantly domestic source. Blank bottles containing only inoculated medium were also prepared. Bottles were sacrificed at intervals by addition of 7M NaOH to draw evolved CO2 into the mineral medium. After equilibration, CO2 concentrations were measured using a carbon analyzer. No statistical difference was found between blanks and PPVE-2 bottles. The blank bottles had < 3 mg/L inorganic carbon, and the reference substance was >60% degraded by day 14. Assuming that all inorganic carbon in the toxicity control was due to sodium benzoate, there was no statistical difference between the positive control and the toxicity control. PPVE-2 did not inhibit activated sludge in this assay. PPVE-2 was not biodegraded in this assay. PPVE-2 is not readily biodegradable.

This test was conducted under an internationally accepted guideline for volatile chemicals, and was in accord with GLP criteria. Therefore, this study is reliable without restrictions.