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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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Data taken from accepted publication with limited details on methods and results. This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labelling and/or risk assessment.

Data source

Reference
Reference Type:
publication
Title:
Biodegradability studies with organic priority pollutant compounds
Author:
Tabak HH, Quave SA, Mashni CI, and Barth EF
Year:
1981
Bibliographic source:
J WPCF, 53(10):1503-1518

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
3 bottles per concentration; volatile fraction also captured and measured
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
trans-dichloroethylene
EC Number:
205-860-2
EC Name:
trans-dichloroethylene
Cas Number:
156-60-5
Molecular formula:
C2H2Cl2
IUPAC Name:
arsenic
Details on test material:
- Purity: not reported

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: settled domestic wastewater as microbial inoculum
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
5 mg/L
Based on:
test mat.
Initial conc.:
10 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimationopen allclose all
Parameter followed for biodegradation estimation:
test mat. analysis
Parameter followed for biodegradation estimation:
TOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: biochemical oxygen demand (BOD) dilution water containing 5 mg of yeast extract per litre, as the synthetic medium
- Test temperature: 25°C
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 250-mL glass-stoppered reagent bottles
- Test performed in closed vessels due to significant volatility of test substance: yes
- Number of culture flasks/concentration: 3

SAMPLING
- Sampling frequency: every 7 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Other: Volatility controls, utilizing a nonbiological system (medium-test compound without inoculum) were held at both refrigerated and 25°C holding temperatures for 10 days and then analysed by GC and for TOC to determine loss of substrate from volatilization.
Reference substance
Reference substance:
other: Phenol

Results and discussion

% Degradationopen allclose all
Parameter:
% degradation (test mat. analysis)
Value:
67
Sampling time:
7 d
Remarks on result:
other: 5 mg/L test
Parameter:
% degradation (test mat. analysis)
Value:
95
Sampling time:
28 d
Remarks on result:
other: 5 mg/L test
Parameter:
% degradation (test mat. analysis)
Value:
40
Sampling time:
7 d
Remarks on result:
other: 10 mg/L test
Parameter:
% degradation (test mat. analysis)
Value:
93
Sampling time:
28 d
Remarks on result:
other: 10 mg/L test
Parameter:
% degradation (test mat. analysis)
Value:
33
Sampling time:
10 d
Remarks on result:
other: percent loss from 5 mg/L non-biologic control due to volatility
Details on results:
The test item exhibits slow biodegradative activity concomitant with relatively moderate rate of volatilization established in the non-biological volatility control systems. The test item was shown to be significantly biodegradable with gradual adaptation observed. The relatively significant volatilization in the non-biological volatility control series did not preclude the biodegradative activity of microbiota in culture media from the relatively high total percentage of loss of test item throughout the study in comparison to the volatility percentage losses.

BOD5 / COD results

Results with reference substance:
Phenol in the 5 and 10 mg/L positive control degraded 100% by Day 14.

Any other information on results incl. tables

 

Average total loss (% biodegradation) of test item in 7 day intervals

Volatile

Loss (%)

10 Days

Test Item

mg/mL

Degradation

summary

Day 7

Day 14

Day 21

Day 28

5°C

25°C

Phenol

(reference)

5

D

96

100

100

100

-

-

Phenol

(reference)

10

D

97

100

100

100

-

-

Test

Item

5

B

67

79

88

95

0

33

Test

Item

10

B

40

76

81

93

0

26

D Significant degradation with rapid adaptation.

B Slow to moderate biodegradative activity, concomitant with significant rate of volatilization.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
other: slow biodegradative activity concomitant with relatively moderate rate of volatilization
Conclusions:
This study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).
The test item exhibits slow biodegradative activity concomitant with relatively moderate rate of volatilization.
Executive summary:

The biodegradability test method used in the study was the static-culture flask-screening procedure using 5- and 10- mg/L concentrations of the test item with a 7-day static incubation followed by three weekly subcultures (total incubation of 28 days. Volatility controls, utilizing a non-biological system (medium and test compound without inoculum) were held at both refrigerated and 25°C holding temperatures for 10 days and then analysed by GC and for TOC to determine loss of the test item from volatilization.

For the 5 mg/mL concentration the 28 day percent total loss of compound was 95%. The volatilization loss was 33%.  In the 10 mg/mL test, total loss was 93% with a 26% loss due to volatilization. The test item exhibits slow biodegradative activity concomitant with relatively moderate rate of volatilization established in the non-biological volatility control systems.  The test item was shown to be significantly biodegradable with gradual adaptation observed. The relatively significant volatilization in the non-biological volatility control series did not preclude the biodegradative activity of microbiota in culture media from the relatively high total percentage of loss of test item throughout the study in comparison to the volatility percentage losses.