Amides, tall-oil fatty, N,N'-(iminodi-2,1-ethanediyl)bis-, phosphates

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

May 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

July 1992

Deviations:

no

GLP compliance:

yes

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): local wastewater treatment plant, ARA Birs (Birsfelden / Switzerland)
- Method of cultivation / Preparation of inoculum for exposure: The aerobic activated sewage sludge was washed three times by centrifugation, decantation of the supernatant liquid phase and resuspension of the solid material in tap water and finally in mineral medium. Aliquots of the homogenized final sludge suspension were weighed, thereafter dried and the dry weight of the suspended solids was determined.
Based on this determination, a calculated amount of wet sludge was suspended in mineral medium to obtain a concentration equivalent to 4 g dry material per liter. During the holding period of three days prior to use, the sludge was aerated at room temperature.

Duration of test (contact time):

28 d

Initial conc.:

21.4 mg/L

Based on:

test mat.

Initial conc.:

15 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium according to testing guidelines; analytical grade salts were dissolved in ultrapure water (ELGA PURELAB Option-Q water purification system)
- Test temperature: 21 - 23 °C
- pH: first test: 7.5 at the start of the test and 7.5 - 7.6 at the end; second test: 7.5 at the start of the test and 7.4 – 7.5 at the end
- pH adjusted: in the second test, the pH was adjusted from 7.7 to 7.5 using a sodium hydroxide solution in all test solutions
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 5-liter amber glass bottles, each fitted with an aeration glass tube reaching nearly the bottom of the vessel and an outlet were used as test vessels. The bottles were filled to a volume of 3000 mL test suspension, which was continuously stirred with the help of magnetic stirrers.
- Number of culture flasks/concentration: 2 in the first test, 3 in the second test
- Method used to create aerobic conditions: CO2-free air was bubbled through the solution in each test vessel at a rate of 30-100 mL/min.
- Measuring equipment: TOC infrared gas analyzer equipped with an automatic sampler
- Test performed in open system: yes
- Details of trap for CO2 and volatile organics if used: The CO2 evolved from the test vessels was collected in 2 x 500 mL gas-absorption flasks containing 300 and 200 mL of 0.05 M NaOH. The air leading connections between the test vessel and the absorption flasks were glass tubes.

SAMPLING
- Sampling frequency:
1. Test: Exposure Day 2, 5, 7, 9, 12, 14, 19, 21, 28, 35 (before acidification), and 36 (after driving off residual CO2)
2. Test: Exposure Day 2, 5, 7, 9, 12, 14, 19, 21, 28 (before acidification), and 29 (after driving off residual CO2).
- Sampling method: An aliquot of 10.0 mL was withdrawn from the absorber flasks nearest to the test vessels for analysis of inorganic carbon (IC). The second absorber flasks were sampled on exposure days 14 and 28 (both tests) and 35 (first test) in order to correct for any carry over of CO2.
- Sample storage before analysis: Samples were immediately analyzed.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 flasks containing inoculated mineral medium
- Reference: 2 flasks containing inoculated mineral medium and sodium benzoate (15 mg TOC/L)
- Toxicity control: 1 flask containing inoculated mineral medium, test material and sodium benzoate (15 mg TOC/L, each)

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

21

Sampling time:

28 d

Remarks on result:

other: 1. test

Key result

Parameter:

% degradation (CO2 evolution)

Value:

26

Sampling time:

28 d

Remarks on result:

other: 2. test

Details on results:

see background material "Tables & Figures - Biodegradation.pdf"

Results with reference substance:

Average biodegradation of the reference item sodium benzoate was >60 % by Exposure Day 5 in both tests, thus confirming suitability of the activated sludge (see background material "Tables & Figures - Biodegradation.pdf").

Validity criteria fulfilled:

yes

Remarks:

IC/TC ratio < 5%; CO2 evolution in the controls < 40 mg/L; degradation of positive controls > 60% within 14 days; degradation in the toxicity flasks > 25% on day 14; criterion for difference between replicates does not apply for UVCB substances

Interpretation of results:

inherently biodegradable

Conclusions:

The test material may be regarded as inherently, primarily biodegradable in the environment.

Description of key information

Biodegradation in water: screening tests: aerobic biodegradation 15 - 48%; mean 26% (CO2-evolution) in 28 days (OECD 301B, EU C.4-C)

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

The test material may be regarded as inherently, primarily biodegradable in the environment (Revised Introduction to the OECD Guidelines for Testing of Chemicals, Section 3, 2006).

[Type of water: freshwater]