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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: screening test, other
Remarks:
Biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions.
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across: supporting information
Principles of method if other than guideline:
The degradation of gasoline (400 mg/L) by a microflora from urban waste water activated sludge was investigated. Unacclimated activated sewage sludge (100 mg dry wt/L) was used as the inoculum. Degradation kinetics were studied in liquid cultures at 30°C by determination of overall O2 consumption and CO2 production and by chromatographic analysis of identifiable compounds including nonane.
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Inocula were prepared from an activated aerobic sludge sampled at an urban waste water treatment plant. A microbial suspension containing about 3g/L dry weight was obtained by centrifugation of the sludge at 15 000 g for 20 min and re-suspension of the centrifuged biomass in the same volume of nutrient solution. The microbial suspension was used to inoculate culture media at a final concentration of 100 mg dry weight/L unless otherwise stated. The centrifuged biomass could be used immediately or stored at -80°C for several months without significant loss of degradation capacity.
Duration of test (contact time):
25 d
Initial conc.:
400 mg/L
Based on:
formulation
Initial conc.:
150 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
see "any other information..." below
Key result
Parameter:
% degradation (test mat. analysis)
Value:
100
Sampling time:
25 d
Details on results:
About 20% degradation was reached on day 2. Extrapolating from the oxygen consumption curve provided in original publication more than 60% degradation were reached before day 10.
Validity criteria fulfilled:
not applicable
Interpretation of results:
other: equivalent to a readily biodegradability result
Conclusions:
The test substance exhibited 100% biodegradation in 25 days and although the test guideline was not a ready biodegradation test, the overall results suggest that it would meet the criteria for ready biodegradation.
Executive summary:

The test substance exhibited 100% biodegradation in 25 days and although the test guideline was not a ready biodegradation test, the overall results suggest that it would meet the criteria for ready biodegradation.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
12 December 1996 - 25 November 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions.
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): aliquot of fresh activated sludge from a domestic wastewater treatment plant in New Jersey, USA

- other: 10^6 CFU/mL

- sludge was obtained on day 1 of test
- total suspended solids of the sludge was determined to be 3.02 g/L.
- sludge was homogenized, the homogenated sample was allowed to settle for 30 min, and the supernatant was decanted and used for final preparation. The supernantant was added at a 1% loading volume of sludge to test medium.
Duration of test (contact time):
70 d
Initial conc.:
49 - 57 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS

- Test temperature: 22 ± 1°C
- Composition of medium: Activated sludge and test medium were combined prior to test material addition. Test medium consited of glass distilled water and mineral salts (Phosphate buffer, Ferric chloride, Magnesium sulfate, Calcium chloride)

TEST SYSTEM
- Culturing apparatus: test vessels were 1L glass flasks placed in a waterbath and electronically monitored for oxygen consumption
- Other: Triplicate test system for test material. Duplicate test system for positive control at approx. concentrations of 51 mg/L through day 28

SAMPLING
- Sampling frequency: continuously monitored by an automated respirometer during a 70 day testing period
Reference substance:
benzoic acid, sodium salt
Test performance:
Sodium benzoate achieved 80.31% biodegradation with a standard deviation of 0.95% by day 14. Therefore the test is considered valid.
Key result
Parameter:
% degradation (O2 consumption)
Value:
10.5
St. dev.:
1.66
Sampling time:
15 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Key result
Parameter:
% degradation (O2 consumption)
Value:
49
St. dev.:
1.81
Sampling time:
43 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Key result
Parameter:
% degradation (O2 consumption)
Value:
60.2
St. dev.:
0.82
Sampling time:
60 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Key result
Parameter:
% degradation (O2 consumption)
Value:
61.81
St. dev.:
1.34
Sampling time:
70 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Details on results:
The biodegradation half-life was < 7 weeks. 10% biodegradation of the test material was achieved on approx. day 15, 50% on approx. day 46.
Test material biodegradability mean at day 28 was 22.4% (21.8, 23,5, 21.8 %).
Test material biodegradability mean at day 70 was 61.81% (60.4, 63.0, 62.1 %).
Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.
Executive summary:

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
20 February 1997 - 25 November 1998
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions.
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Principles of method if other than guideline:
Based on OECD guideline 301F the test phase was prolonged for inherent testing.
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): aliquot of fresh activated sludge from a domestic wastewater treatment plant in New Jersey, USA

-other: microbial activity of of inoculum: 10^5 CFU/mL

- Inoculum preparation for Inherent biodegradability testing: On day 70 of the ready biodegradability test, all systems were disassembled. The contents of MRD-96-587 test systems were centrifuged at 10,000 rpm for 20 min. The supernatant was poured off and filtered through a Whatman #4 filter. The solids were combined and then resuspended with a minimal volume of filtered supernatant.The final volume was ~ 150mL. The remaining supernatant was then filtered through 0.45 µm microfiber filters. The biomass solids remaining on the filter were gently scraped into the previous collected biomass. The harvested biomass was blended for approx. 2 min. Exactly 100 mL of the harvested biomass was added to 10mL of test medium. Each new blank, sodium benzoate and MRD-96-587 test system contained one liter of the inoculated test medium. The microbial activity of the inoculum was determined to be 100000 CFU/mL. The phase 2 inherent biodegradability test was the conducted for 75 days.
Duration of test (contact time):
75 d
Initial conc.:
49 - 57 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS

- Test temperature: 22 ± 1°C
- Composition of medium: Activated sludge and test medium were combined prior to test material addition. Test medium consited of glass distilled water and mineral salts (Phosphate buffer, Ferric chloride, Magnesium sulfate, Calcium chloride)

TEST SYSTEM
- Culturing apparatus: test vessels were 1L glass flasks placed in a waterbath and electronically monitored for oxygen consumption
- Other: Triplicate test system for test material. Duplicate test system for positive control at approx. concentrations of 51 mg/L through day 28

SAMPLING
- Sampling frequency: continuously monitored by an automated respirometer during a 70 day testing period
Reference substance:
benzoic acid, sodium salt
Test performance:
In the inherent test sodium benzoate achieved 97.76% with a SD of 1.13% by day 14. Therefore the test is considered valid.
Key result
Parameter:
% degradation (O2 consumption)
Value:
64.06
St. dev.:
10.53
Sampling time:
75 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Key result
Parameter:
% degradation (O2 consumption)
Value:
60.3
St. dev.:
9.59
Sampling time:
42 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Key result
Parameter:
% degradation (O2 consumption)
Value:
51.3
St. dev.:
11.91
Sampling time:
28 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Key result
Parameter:
% degradation (O2 consumption)
Value:
26.83
St. dev.:
8.59
Sampling time:
11 d
Remarks on result:
other: MRD-96-587, Isopar C (U.S.); values based on ThOD of test material.
Results with reference substance:
>60% biodegradation by day 14
Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.
Executive summary:

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
9 January - 1 July 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Chester Sewage Works, Welsh Water
- Preparation of inoculum for exposure: Inoculum was collected the day before the test. It was homogenized for two minutes, then allowed to settle. The supernatent was filtered through medical gauze.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: OECD mineral salts medium
- Test temperature: 21.4-21.7 degree C
- Aeration of dilution water: aerated with moist air for 22 h


TEST SYSTEM
- Culturing apparatus: respirometer flask
- Number of culture flasks/concentration: 3 test substance only, 2 test substance and sodium benzoate (inhibition controls)
- Measuring equipment: Co-ordinated Environmental Servies Ltd. Aerobic Respirometer
- Test performed in closed vessels due to significant volatility of test substance: yes, closed with CO2 trap

SAMPLING
- Sampling frequency: hourly
- Sampling method: respirometer


CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Other: 2 controls using sodium benzoate


STATISTICAL METHODS: C.E.S. CESAN Data Analysis Program v1.1
Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (O2 consumption)
Value:
83
St. dev.:
16
Sampling time:
16 d
Remarks on result:
other: stated in study: end of 10 day window; reading from graph indicates day 16
Key result
Parameter:
% degradation (O2 consumption)
Value:
98
St. dev.:
12
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
81
Sampling time:
28 d
Remarks on result:
other: inhibition control
Details on results:
% degradation of test samples at end of 10 day window: 87, 96, 65
% degradation of test samples on day 28: 104, 104, 84
% degradation of inhibition controls: 81, 82 - test substance does not inhibit degradation.
Results with reference substance:
The reference substance was 95% degraded by day 14, and degraded 104% (mean) by day 28.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
This study examined the ready biodegradability of hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, < 5% hexane. Activated sludge was exposed to a concentration of 100 mg/l of test substance. The O2 consumption was then monitored for the next 28 days. Sodium benzoate was used as the reference substance. The test substance was 98% degraded at the end of 28 days, and 83% degraded at the end of the 10-day window. The reference substance was 104% degraded, therefore the test is valid. The test substance is readily biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.
Executive summary:

This study examined the ready biodegradability of hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, < 5% hexane. Activated sludge was exposed to a concentration of 100 mg/l of test substance. The O2 consumption was then monitored for the next 28 days. Sodium benzoate was used as the reference substance. The test substance was 98% degraded at the end of 28 days, and 83% degraded at the end of the 10-day window. The reference substance was 104% degraded, therefore the test is valid. The test substance is readily biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: A standard test method was not used and there is little information to assess the reliability of the study, but the results are consistent with the biodegradation database for this substance. The study was conducted prior to GLP standards.
Justification for type of information:
A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.
Reason / purpose for cross-reference:
read-across: supporting information
Principles of method if other than guideline:
Guideline procedure that used non acclimated sediment as an inoculum
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: sediment, seawater, non-adapted
Key result
Parameter:
not specified
Value:
100
Sampling time:
15 d
Remarks on result:
other: test 1
Key result
Parameter:
not specified
Value:
67
Sampling time:
15 d
Remarks on result:
other: test 2
Details on results:
100 and 58% biodegradation was measured after 15 days incubation with an unacclimated inoculum in two separate tests.

% Biodegradation of test substance after days (test 1):
5 day = 27%
15 days = 100%

% Biodegradation of test substance after days (test 2):
5 day = 18%
15 days = 58%
Validity criteria fulfilled:
not applicable
Interpretation of results:
readily biodegradable
Conclusions:
The test substance exhibited 100 and 58% biodegradation after 15 days incubation in two tests with a non acclimated sediment inoculum.
Executive summary:

The test substance exhibited 100 and 58% biodegradation after 15 days incubation in two tests with a non acclimated sediment inoculum.

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: Comparable to guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
other: American Public Health Association (1971) Standard methods for the examination of water and waste water, 13th ed. American Public Health Association, Inc., Washington, D.C.
GLP compliance:
no
Remarks:
guideline procedure that used soil as an inoculum
Oxygen conditions:
aerobic
Inoculum or test system:
natural soil
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Hudson-Collamar silt loam soil
- Preparation of inoculum for exposure: suspension of Hudson-Collamar silt loam soil in distilled water
Duration of test (contact time):
20 d
Initial conc.:
3.3 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: solution containing 1.6 g of K2HPO4, 0.82 g of (NH4)2SO, 0.40 g of KH2PO, 0.20 g of MgSO4.7H2O, 25 mg of CaCl2.2H2O, and 2.3 mg of FeCl2.6H2O per liter.
- Test temperature: 25°C
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration: 2
- Test performed in closed vessels due to significant volatility of test substance: yes


SAMPLING
- Sampling frequency: daily
Reference substance:
not specified
Parameter:
% degradation (O2 consumption)
Value:
28.3
Sampling time:
2 d
Remarks on result:
other: re-calculated by submitter based on ThOD and reported value of 3.3 mg/L oxygen consumption
Parameter:
% degradation (O2 consumption)
Value:
63.4
Sampling time:
5 d
Remarks on result:
other: re-calculated by submitter based on ThOD and reported value of 7.4 mg/L oxygen consumption
Key result
Parameter:
% degradation (O2 consumption)
Value:
70.3
Sampling time:
10 d
Remarks on result:
other: re-calculated by submitter based on ThOD and reported value of 8.2 mg/L oxygen consumption
Validity criteria fulfilled:
not applicable
Interpretation of results:
other: equivalent to a readily biodegradability result
Conclusions:
The test substance exhibited greater than 60% biodegradation in less than 28 days and although the test guideline was not a ready biodegradation test, the overall results suggest that it would meet the criteria for ready biodegradation.
Executive summary:

The test substance exhibited greater than 60% biodegradation in less than 28 days and although the test guideline was not a ready biodegradation test, the overall results suggest that it would meet the criteria for ready biodegradation.

Description of key information

There is data available for this substance. Additionally, key data is available for structural analogues, Nonane, Hydrocarbons, C7 -C9, isoalkanes and Hydrocarbons, C6 -C7, isoalkanes, n-alkanes, isoalkanes, cyclics, < 5% hexane and presented in the dossier. The data is read across to this substance based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

Nonane exhibited 100% biodegradation in 25 days and although the test guideline was not a ready biodegradation test, the overall results suggest that it would meet the criteria for ready biodegradation.

Hydrocarbons, C7-C9, isoalkanes, is inherently biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

This study examined the ready biodegradability of hydrocarbons, C6-C7, n-alkanes, isoalkanes, cyclics, < 5% hexane. The test substance was 98% degraded at the end of 28 days, and 83% degraded at the end of the 10-day window. The reference substance was 104% degraded, therefore the test is valid. The test substance is readily biodegradable under the conditions of the study and is not expected to persist in the environment under aerobic conditions.

Nonane exhibited 100 and 58% biodegradation after 15 days incubation in two tests with a non acclimated sediment inoculum.

Octane exhibited greater than 60% biodegradation in less than 28 days and although the test guideline was not a ready biodegradation test, the overall results suggest that it would meet the criteria for ready biodegradation.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information