Fatty acids, tall-oil, compds. with diethanolamine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

July 1, 1997 to July 30, 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

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): A mixed population of activated sewage sludge micro-organisms was obtained from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Belper, Derbyshire, UK, which treats predominantly domestic sewage.
- Preparation of inoculum for exposure: The sample of activated sewage sludge was maintained on continuous aeration. A sample of the activated sewage sludge was washed three times by settlement and resuspension in culture medium to remove any excessive amounts of dissolved organic carbon (DOC) that may have been present. A sub-sample of the washed sewage sludge was then removed and the suspended solids concentration determined.

Duration of test (contact time):

28 d

Initial conc.:

10 other: mg C/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: The culture medium used in this study was same as that recommended in the OECD Guidelines (i.e., medium contained phosphate buffer, magnesium sulphate, calcium chloride and ferric chloride in purified water).
- Test temperature: 21 °C
- pH: 7.4
- Continuous darkness: Yes
- Suspended solids concentration: 30 mg suspended solids (ss)/L


TEST SYSTEM
- Culturing apparatus: 5 L flasks (containing 3 L of solution) mounted with an aeration tube on a magnetic stirrer.
- Number of culture flasks: 2 each for test material, reference material and inoculum control and 1 for toxicity control
- Test performed in closed vessels: Yes
- Method used to create aerobic conditions: The culture vessels were sealed and CO2-free air was bubbled through the solution at a rate of approximately 40 mL/min and stirred continuously by magnetic stirrer.
- Method of producing CO2 free air: The CO2-free air was produced by sparging compressed air through the following series:
i) Three 500 mL Dreschel bottles filled with 350 mL 10N NaOH
ii) One 500 mL Dreschel bottle filled with 350 mL 0.025N Ba(OH)2
iii) One empty 500 mL Dreschel bottle to prevent liquid carry-over to the test vessels.

- Details of trap for CO2 and volatile organics if used: The CO2 produced by degradation was collected in two 500 mL Dreschel bottles containing 350 mL of 0.05 M NaOH. The CO2 absorbing solutions were prepared using purified de-gassed water.
- Other: Approximately 24 hours prior to addition of the test and the reference substance the vessels were filled with 2400 mL of culture medium and 48.6 mL of inoculum and aerated overnight. On Day 0 the test and reference substances were added and the volume in all the vessels adjusted to 3 L by the addition of culture medium.


SAMPLING
- Sampling frequency: Samples (2 mL) were taken from the first CO2 absorber vessel on Days 0, 1, 2, 3, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 27, 28 and 29 days for CO2 analysis and 0 and 28 days for DOC analysis. The second absorber vessel was sampled on Day 0 and 29.
- Sample storage before analysis: The samples taken on Days 0, 1, 2, 3, 6, 8, 10, 14, 16, 20, 22, 24, 27, 28 and 29 were analysed for CO2 immediately and the samples taken on Days 12 and 18 were stored deep frozen at -20˚C (not analysed later on as the degradation of the test substance was not found to significantly increase during this time).
-Other: On Day 28, 1 mL of concentrated HCI added to flasks in order to eject all the remaining CO2 and last sampling was carried out on the Day 29.


ANALYSIS:
- Measuring equipments: lonics 15558 TOC analyzer and a Dohrmann DC-190 TOC analyser for CO2 analysis and Dohrmann DC-190 TOC analyser for DOC analysis.


CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes (Two test flasks containing only inoculum)
- Toxicity control: Yes; (One test flask containing test substance + reference substance + inoculum); final concentration: 20 mgC/L
- Reference control: Yes; (Two test flasks containing reference substance, i.e., sodium benzoate); final concentration: 10 mgC/L

Reference substance:

benzoic acid, sodium salt

Remarks:

tested at 17.1 mg/L concentration (i.e., equivalent to 10 mg carbon/L)

Preliminary study:

Preliminary investigational work was carried out to assess any toxic effect of the test substance on the sewage sludge micro-organisms according to the OECD Guideline No 209. The test period was increased from 3 hours to 5 days in order to determine whether any long term toxic effects of the test substance occurred. The initial experiment was terminated after 3 days aeration as the variation between the control vessels was greater than the limits given in the guideline. The concentration employed was 20 mgC/L.
However, the results did not conclusively show that the test substance inhibited the respiration of sewage sludge micro-organisms at the concentration employed in the test (refer to the Table 3 in the pdf attached under the 'attached background material' section). Hence, in the light of this a toxicity control vessel was included in the test at 20 mgC/L final concentration.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 62

Sampling time:

28 d

Key result

Parameter:

% degradation (DOC removal)

Value:

ca. 75

Sampling time:

28 d

Details on results:

- CO2 evolution: The test substance attained 62% degradation after 28 days. Despite attaining in excess of 60% biodegradation after 28 days the 10-day window validation criterion, whereby greater than 60% degradation must be attained within 10 days of the degradation exceeding 10%, was not achieved.
- DOC analysis: Analysis of the test media from the test substance culture vessels on Days 0 and 28 for dissolved organic carbon (DOC) gave percentage degradation values of 74% and 76% respectively for replicates R1 and R2, and 100% for the toxicity control.

The degradation rates calculated from the results of the DOC analysis were higher than those calculated from the CO2 evolution analysis. This is considered to be due to the incorporation of the test substance into the cellular biomass prior to degradation, and hence CO2 evolution occurring.

- Toxicity control: The toxicity control attained 81 % degradation after 28 days thereby confirming that the test substance was not toxic to the sewage treatment micro-organisms used in the study. The increase in inorganic carbon in the first absorber vessels on Day 29 did not result in an increase in the percentage degradation value for the toxicity control from 81 % on Day 28.

- Reference control: Sodium benzoate attained 99% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions. The increase in inorganic carbon in the first absorber vessels on Day 29 resulted in an increase in the percentage degradation value for the standard material from 99% on Day 28 to 100% on Day 29.

- Inorganic carbon values for the test substance, reference substance (sodium benzoate) and control vessels at each analysis occasion are given in Table 1 given in attached pdf under the 'attached background material'. Percentage biodegradation of the test and reference substances are given in Table 2

Results with reference substance:

The reference substance attained 99% degradation after 28 days thereby confirming the suitability of the inoculum and test conditions.

- The results of the inorganic carbon analysis of samples from the first absorber vessels on Day 29 showed an increase in all replicate vessels. These increases are considered to be due to CO2 present in solution being driven off by the addition of hydrochloric acid on Day 28 and resulted in an increase in the percentage degradation value for the test substance from 62% on Day 28 to 68% on Day 29.

- Inorganic carbon analysis of the samples from the second absorber vessels on Day 29 confirmed that no significant carry-over of CO2 into the second absorber vessels occurred.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the study conditions, the test substance was considered to be readily biodegradable.

Executive summary:

A study was performed to assess the ready biodegradability of the test substance, C16-18 and C18-unsatd. DEA, according to OECD Guideline 301 B and EU Method C.4-C, in compliance with GLP. The substance was inoculated with activated domestic sewage sludge microorganisms at a concentration of 10 mg total organic carbon (TOC)/L in sealed culture vessels in the dark at 21⁰C for 28 d. The test substance attained 62% degradation after 28 d. The degradation rate was also calculated on Days 0 and 28 for dissolved organic carbon (DOC) and was found to be 74 and 76%, respectively for the two replicates and 100% for the toxicity control. Further, the reference substance, sodium benzoate attained 99% degradation after 28 d, thereby confirming the suitability of the inoculum and test conditions. Under the study conditions, the test substance was considered to be readily biodegradable (Mead, 1997).

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 7, 1997 to June 4, 1997

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal wastewater treatment plant Hochdal.
- Concentration of sludge: 1 ml/L culture medium

Duration of test (contact time):

ca. 28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Initial conc.:

5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Because of the low solubility of the test substance, a dispersing agent (Disponil nonylphenol + 9.5 EO +5EO (1:1)) was used.

Reference substance:

benzoic acid, sodium salt

Remarks:

2 mg/L

Key result

Parameter:

other: Biological oxygen demand (BOD)/Theoretical oxygen demand (ThOD)

Value:

ca. 60

Sampling time:

28 d

Remarks on result:

other: 2 mg/L test substance concentration

Key result

Parameter:

other: (BOD/ThOD)

Value:

> 52

Sampling time:

28 d

Remarks on result:

other: 5 mg/L test substance. Not enough rest oxygen in the test system so that values correspond to minimum degradation rates

Details on results:

The mean degradation rate of the test substance was 60 % within 28 d.

Results with reference substance:

The reference substance reached the pass levels for ready biodegradability within 7 days.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the study conditions, the test substance was considered to be readily biodegradable.

Executive summary:

A study was conducted to determine the biodegradability of the test substance, C16-18 and C18-unsatd. DEA, according to OECD Guideline 301D (Closed bottle test), in compliance with GLP. A solution of the test substance at 2 and 5 mg/L was inoculated with activated sludge (1 ml/L) and placed in closed bottles in the dark for 28 d. Due to limited solubility, a dispersing agent (Disponil nonylphenol + 9.5 EO +5EO (1:1)) was used. Degradation was followed by determining biological oxygen demand (BOD) on Days 7, 14, 21 and 28. The reference substance used was sodium benzoate. The reference substance reached the pass levels for ready biodegradability within 7 d. The mean degradation extent of the test substance was 60% within 28 d. Under the study conditions, the test substance was considered to be readily biodegradable (Richterich, 1997).

Description of key information

A study was conducted to determine the biodegradability of the test substance, C16-18 and C18-unsatd. DEA, according to OECD Guideline 301D (Closed bottle test), in compliance with GLP. A solution of the test substance at 2 and 5 mg/L was inoculated with activated sludge (1 ml/L) and placed in closed bottles in the dark for 28 d. Due to limited solubility, a dispersing agent (Disponil nonylphenol + 9.5 EO +5EO (1:1)) was used. Degradation was followed by determining biological oxygen demand (BOD) on Days 7, 14, 21 and 28. The reference substance used was sodium benzoate. The reference substance reached the pass levels for ready biodegradability within 7 d. The mean degradation extent of the test substance was 60% within 28 d. Under the study conditions, the test substance was considered to be readily biodegradable (Richterich, 1997).

A study was performed to assess the ready biodegradability of the test substance, C16-18 and C18-unsatd. DEA, according to OECD Guideline 301 B and EU Method C.4-C, in compliance with GLP. The substance was inoculated with activated domestic sewage sludge microorganisms at a concentration of 10 mg total organic carbon (TOC)/L in sealed culture vessels in the dark at 21⁰C for 28 d. The test substance attained 62% degradation after 28 d. The degradation rate was also calculated on Days 0 and 28 for dissolved organic carbon (DOC) and was found to be 74 and 76%, respectively for the two replicates and 100% for the toxicity control. Further, the reference substance, sodium benzoate attained 99% degradation after 28 d, thereby confirming the suitability of the inoculum and test conditions. Under the study conditions, the test substance was considered to be readily biodegradable (Mead, 1997).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater