Registration Dossier

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:
11 Jul 2014 - 8 Aug 2014
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:
2014
Report Date:
2014

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material: MTDID 16437
- Substance type: pure active substance
- Physical state: liquid
- Analytical purity: 98.5%
- Stability under test conditions: Slow hydrolysis in neutral or alkaline solution, hydrolysis in acidic solution
- Storage condition of test material: At room temperature in the dark under nitrogen
- Other: Prolonged exposure to moisture and oxygen initiates slow degradation

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Secondary effluent freshly obtained from a municipal sewage treatment plant:
'Waterschap Aa en Maas','s-Hertogenbosch, The Netherlands
- Preparation of inoculum for exposure: Secondary effluent was filtered through a coarse filter paper, the first 200 ml was discarded. The filtrate was kept aerated until inoculation.
- Inoculation level: Four mL/L, ca 2.4 mL in test bottles
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
15 mg/L
Based on:
test mat.
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium, concentrations as per OECD 301D
- Solubilising agent (type and concentration if used): None, test material added directly to test bottles by volume.
- Test temperature: 21.8 °C to 22.5 °C.
- pH: 7.4 - 7.5 at test initiation
- pH adjusted: No
- Aeration of dilution water: Dilution water not used, mineral medium was left at room temperature overnight before test, DO concentration measured before test began to assure saturation. Test bottles contained 8.6-8.7 mg/L dissolved oxygen at test initiation.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: ca. 300 mL BOD bottles with glass stoppers
- Number of culture flasks/concentration: Two per concentration per day.
- Method used to create aerobic conditions: Medium allowed to stand overnight before inoculation
- Measuring equipment: WTW oxygen meter with WTW CellOx 325 oxygen electrode, electrolyte type ELY/G.
- Test performed in closed vessels due to significant volatility of test substance: yes

SAMPLING
- Sampling frequency: At day 0, 7, 14, 21 and 28.
- Sampling method: Stopper removed, oxygen electrode inserted and dissolved oxygen concentration measured. Because they did not contain a volatile test material, bottles for reference substance and inoculum blank were measured at test initiation and returned to the study to be measured again on Day 7. All other bottles were measured and discarded. pH in sample bottles measured at start of test only.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes (eight bottles)
- Abiotic sterile control: No
- Toxicity control: Yes (six bottles), same amount of test and reference substances combined as in test substance low concentration (30 mg/L) and reference substance (2 mg/L) bottles separately.

STATISTICAL METHODS:
ThOD and BOD calculated per OECD guidelines
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
7
Sampling time:
28 d
Remarks on result:
other: at 15 mg/L level
Parameter:
% degradation (O2 consumption)
Value:
1
Sampling time:
28 d
Remarks on result:
other: at 30 mg/L level
Details on results:
Test substance degradation in the 30 mg/L series was greater on day 21 than day 28.

BOD5 / COD results

Results with reference substance:
86% degradation of reference substance on day 7, 104% degradation on day 14
Toxicity was assessed by comparison of toxicity test bottle oxygen depletion with sum of reference substance and high test substance results. No difference was observed (see Table 1), so the test substance was not considered to inhibit activated sludge.

Any other information on results incl. tables

Table 1, pH at the start and oxygen concentration during the test

Series

Content

pH at τ=0

Flask No.

Oxygen concentration (mg O2/L) after x days

0

7

14

21

28

Inoculum blank

Mineral medium,

7.5

A

8.64

7.38

8.87

8.22

8.40

inoculum

B

8.64

7.54

8.68

8.15

7.94

mean

8.64

7.46

8.78

8.19

8.17

Procedure control

Mineral medium,

7.5

A

8.70

6.18

7.12

inoculum

B

8.68

6.16

7.30

sodium acetate (2 mg/l)

mean

8.69

Test substance, low

Mineral medium,

7.4

A

8.69

7.47

8.71

7.96

7.99

inoculum

B

8.69

7.48

8.62

7.98

7.96

PPVE (15 mg/L)

mean

8.69

Test substance, high

Mineral medium,

7.5

A

8.70

7.48

8.11

7.32

8.26

inoculum

B

8.68

7.47

8.52

7.24

8.11

PPVE (30 mg/L)

mean

8.69

Toxicity control

Mineral medium,

7.5

A

8.70

6.48

6.89

inoculum

B

8.72

6.48

7.37

PPVE (30 mg/L) plus sodium acetate (2 mg/l)

mean

8.71

Table 2, Mean values of oxygen depletion at different points in time ¹

Series

Content

Flask No.

Oxygen depletion (mg BOD/L) after x days

7

14

21

28

Procedure control

Mineral medium,

A

1.33

1.71

inoculum

B

1.35

1.53

sodium acetate (2 mg/l)

Test substance, low

Mineral medium,

A

0.04

0.12

0.28

0.23

inoculum

B

0.03

0.21

0.26

0.26

PPVE (15 mg/L)

Test substance, high

Mineral medium,

A

0.03

0.72

0.92

-0.04

inoculum

B

0.04

0.31

1.00

0.11

PPVE (30 mg/L)

Toxicity control

Mineral medium,

A

1.05

1.96

inoculum

B

1.05

1.48

PPVE (30 mg/L) plus sodium acetate (2 mg/L)

1, Values corrected for oxygen depletion in blank control (mean value) 

Table 3, Biodegradation percentages at different points in time

Series

Content

Flask No.

Oxygen depletion (mg BOD/L) after x days

7

14

21

28

Procedure control

Mineral medium,

A

85

110

inoculum

B

87

98

sodium acetate (2 mg/l) ¹

Mean

86

104

Test substance, low

Mineral medium,

A

1

3

8

6

inoculum

B

1

6

7

7

PPVE (15 mg/L) ²

Mean

1

5

8

7

Test substance, high

Mineral medium,

A

0

10

13

-1

inoculum

B

1

4

14

2

PPVE (30 mg/L) ²

Mean

1

7

14

1

1, ThOD of positive control sodium acetate: 0.78 mg O2/mg

2,: ThOD of PPVE: 0.24 mg O2/mg

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
O2 depletion in the inoculum blank was below 1.5 mg O2/l after 28 days, residual O2 in test bottles > 0.5 mg/l at any time, control substance degraded >60% within 14 days, differences of duplicate biodegradation values less than 20% as mg O2/L
Interpretation of results:
other: Not readily biodegradable
Conclusions:
PPVE is not readily biodegradable in a 28-day Closed Botlle (OECD301D) test.
Executive summary:

Biodegradation of PPVE was assessed in a 28-day closed bottle test (OECD TG301D) conducted under GLP criterion. Sodium acetate was used as reference. PPVE loaded at 15 mg/L showed 7% oxygen depletion v. controls, and PPVE loaded at 30 mg/L showed 1% oxygen depletion.. In toxicity controls, PPVE at a concentration of 30 mg/L did not measurably prevent the reference substance sodium acetate from being degraded. PPVE is not readily biodegradable. The study was conducted in accord with internationally accepted guidelines under GLP criteria. It is reliable without restriction and is suitable for use in Risk Assessment, Classification & Labelling, and PBT Analysis