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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
04-02-2010 - 13-04-2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Test performed under GLP according guidelines with (minor) acceptable deviations, meeting all validity criteria.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
yes
Remarks:
acceptable deviations
Principles of method if other than guideline:
Minor deviations from the guidelines of the Closed Bottle test were introduced; a) ammonium chloride was not added to prevent oxygen consumption due to nitrification (omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound), and b) river water was used as inoculum. One extension from the guidelines of the Closed Bottle test was introduced. The Closed Bottle test was prolonged by
measuring the course of the oxygen decrease in the bottles of day 28 using a special funnel
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Details on test material:
Test material
A sample of tall oil diethylenetriamine imidazoline was received from AkzoNobel
Surface Chemistry on 18-12-2009. The following test substance data were
submitted by the sponsor, who accepted full responsibility for the validity thereof.
- chemical name (active ingredient) Tall oil diethylenetriamine imidazoline
- CAS reg. No. (active ingredient) 68442-97-7
- Composition (annex 2) tall oil diethylenetriamine imidazoline (94%)
Ratio amidoamide:imidazoline 45:55
diethylentriamine 3.6%
fatty acid 2.0%
- product name Armohib CI 219
- batch/Lot No. S000922
- appearance light brown liquid
- stability not relevant in test
- solubility in water suspendable at test concentrations
- storage at ambient temperature in the dark
The concentrations cited in this report refer to the as-received sample of tall oil diethylenetriamine imidazoline

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
natural water
Details on inoculum:
River water was sampled from the Rhine near Heveadorp, The Netherlands (04-02-2010).
The river water was aerated for 7 days before use to reduce the endogenous respiration (van Ginkel and Stroo, 1992).
River water without particles used as inoculum was obtained by removing solids sedimented by
gravity. The particles were removed by sedimentation.
Duration of test (contact time):
60 d
Initial test substance concentration
Initial conc.:
2 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Test bottles
The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.

Nutrients and stock solutions
The river water used in the Closed Bottle test was spiked per liter of water with 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.3 mg Na2HPO4.2H2O, 22.5 mg MgSO4.7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3.6H2O. Ammonium chloride was not added to prevent nitrification.
Sodium acetate and the test substance were added to the bottles using stock solutions of 1.0 g/L.

Test procedures
The Closed Bottle test was performed according to the study plan. The study plan was developed from ISO Test Guidelines (1994).
Use was made of 10 bottles containing only river water (inoculum and medium), 10 bottles containing river water and silica gel (2 g/bottle),
10 bottles containing river water, silica gel and test substance, and 6 bottles containing sodium acetate and river water. The concentrations
of the test substance and sodium acetate in the bottles were 2.0 and 6.7 mg/L, respectively. Each of the prepared solutions was dispensed into the
respective group of BOD bottles so that all bottles were completely filled without air bubbles. The zero time bottles were immediately analyzed for
dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were
withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28. One extension from the protocol of the Closed Bottle test was introduced. The Closed Bottle test was prolonged by measuring the course of the oxygen decrease in the bottles of day 28 using a special funnel.
This funnel fitted exactly in the BOD bottle. Subsequently, the oxygen electrode was inserted in the BOD bottle to measure the oxygen concentration. The medium dissipated by the electrode was collected in the funnel. After withdrawal of the oxygen electrode the medium collected flowed back into the BOD bottle, followed by removal of the funnel and closing of the BOD bottle (van Ginkel and Stroo 1992).


Calculation of the results:

Calculation of endogenous respiration
The endogenous respiration (oxygen depletion in the control) was calculated as follows;
Oxygen depletion (endogenous respiration) (mg/L) = Mc (day 0) - Mc (day 28)
Mc is the mean oxygen level in the control bottle inoculated with river water.

Calculation of the theoretical oxygen demand (ThOD)
The ThODs of tall oil diethylenetriamine imidazoline, and sodium acetate were calculated from their molecular formulae and
molecular weights. The calculated theoretical oxygen demand (ThOD) and Chemical Oxygen Demand
(COD) of tall oil diethylenetriamine imidazoline are both 2.7 mg/mg. The ThOD of sodium acetate is 0.8 mg/mg.


Calculation of the biochemical oxygen demand (BOD)
Provided that the oxygen concentrations in all bottles at the start of the test were equal, the amounts of oxygen consumed in test and
reference compound bottles were calculated as follows:
Oxygen consumptionn (mg/L) by test substance = Mcs - Mt
Oxygen consumptionn (mg/L) by reference compound = Mc - Ma
Mc or cs is the mean oxygen level in the control bottles filled with river water spiked with mineral salts with (cs) and without silica gel (c) n days after the start of the test.
Mt or a is the mean oxygen concentration in the bottles containing the test substance (t) or the reference compound, sodium acetate (a), present in
river water spiked with mineral salts n-days after the start of the test.
The biological oxygen demand (BOD) mg/mg of the test substance and sodium acetate was calculated by dividing the oxygen consumption by
the concentration of the test substance and sodium acetate in the closed bottle, respectively.

Calculation of the biodegradation percentages
The biodegradation was calculated as the ratio of the biochemical oxygen demand (BOD) to the theoretical oxygen demand (ThOD) or Chemical
Oxygen Demand (COD).
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
24
Sampling time:
28 d
Remarks on result:
other: 61% biodegradation at day 60
Details on results:
Toxicity
Inhibition of the degradation of a well-degradable compound, e.g. sodium acetate by the test substance in the Closed Bottle test was not determined because possible toxicity of tall oil diethylenetriamine imidazoline to microorganisms degrading acetate is not relevant. Inhibition of the endogenousrespiration of the inoculum by the test substance tested in the presence of silica gel was not detected. Inhibition of the biodegradation due to
the "high" initial concentration of the test substance is therefore not expected.

Test conditions
The pH of the media was 8.0 at the start of the test. The pH of the medium at day 28 was 7.9 (control and test) and 7.8 (control with silica gel).
Temperatures were within the prescribed temperature range of 22 to 24°C.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
endogenous respiration of 1.4 mg/L at day 28, differences of the replicate values at day 28 less than 20%. 87% biodegradation of the reference compound, at day 14; oxygen concentrations >0.5 mg/L in all bottles during the test period
Interpretation of results:
inherently biodegradable
Conclusions:
Test performed under GLP according guidelines with (minor) acceptable deviations, meeting all validity criteria.
Tall oil diethylenetriamine imidazoline was biodegraded 24% at day 28 in the Closed Bottle test. This test substance should therefore not be classified as readily biodegradable. In the prolonged Closed Bottle test tall oil diethylenetriamine imidazoline was biodegraded 61% at day 60.
The biodegradation reached at the day 60 of the test demonstrates that this test substance is not persistent.
Executive summary:

In order to assess the biotic degradation, a ready biodegradability test was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined in the Closed Bottle test performed according to slightly modified OECD, EU and ISO Test Guidelines, and in compliance with the OECD principles of Good Laboratory Practice. The test was prolonged because the pass level was not reached at Day 28. Tall oil diethylenetriamine imidazoline in the presence of silica gel did not cause a reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum. Tall oil diethylenetriamine imidazoline was biodegraded 24% at day 28 in the Closed Bottle test. This test substance should therefore not be classified as readily biodegradable. In the prolonged Closed Bottle test tall oil diethylenetriamine imidazoline was biodegraded 61% at day 60. The biodegradation reached at the day 60 of the test demonstrates that this test substance is not persistent. The test is valid as shown by an endogenous respiration of 1.4 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded 87% of its theoretical oxygen demand after 14 days. Finally, the most important criterion was met by oxygen concentrations >0.5 mg/L in all bottles during the test period.