Oleic acid, compound with (Z)-N-octadec-9-enylpropane-1,3-diamine

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

Study period:

Experimental starting date 05-06-2018; Experimental completion date 07-08-2018

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:

yes

Remarks:

Minor deviations from the guidelines of the Closed Bottle test (OECD TG 301D) see below

Principles of method if other than guideline:

minor deviations were introduced; a) ammonium chloride was omitted from the medium 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 instead of an effluent/extract/mixture was used as inoculum.

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

natural water: freshwater

Details on inoculum:

River water was sampled from the Rhine near Heveadorp, The Netherlands (31-05-2018). The nearest plant (Arnhem-Zuid) treating domestic wastewater biologically was 3 km upstream. The river water was aerated for 7 days before use to reduce the endogenous respiration (van Ginkel and Stroo, 1992). River water without particles was used as inoculum. The particles were removed by sedimentation after 1 day while moderately aerating.

Duration of test (contact time):

60 d

Initial conc.:

2 mg/L

Based on:

test mat.

Initial conc.:

5.92 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test procedures
The Closed Bottle test (OECD TG 301D) 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 with nutrients, 6 bottles containing river water with nutrients and sodium acetate, 10 bottles containing river water with nutrients and test substance. 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).

Reference substance:

acetic acid, sodium salt

Remarks:

6.7 mg/L

Key result

Parameter:

% degradation (O2 consumption)

Value:

52

Sampling time:

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

60 d

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 the test substances to microorganisms degrading acetate is not relevant. Inhibition of the endogenous respiration of the inoculum by the test substance at day 7 was not detected (Table I). Therefore, no inhibition of the biodegradation due to the "high" initial test substance concentration is 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 8.0 (control and test). The temperature ranged from22.6 to 22.9°C which is within the prescribed temperature range of 22 to 24°C.


Biodegradability
N-(oleyl alkyl)-1,3-propanediamine oleates was biodegraded by 52% at day 28 in the Closed Bottle test (Table II). In the prolonged Closed Bottle test (enhanced biodegradability test) the test substance is biodegraded by 64% at day 60 (Figure and Table II). The biodegradation percentage of >60% demonstrates that test substance is completely biodegradable. Moreover, the biodegradation in excess of 60% within the 60-day test period allows classification of the test item as not persistent

Results with reference substance:

The biodegradation percentage of the reference compound, sodium acetate, at day 14 was 79

Table I Dissolved oxygen concentrations (mg/L) in the closed bottles.

Time (days)	Oxygen concentration (mg/L)
	Oc	Ot	Oa
0	8.6	8.6	8.6
	8.6	8.6	8.6
Mean (M)	8.6	8.6	8.6
7	8.0	5.8	4.5
	7.8	5.9	4.4
Mean (M)	7.9	5.9	4.5
14	7.3	5.0	3.4
	7.4	4.9	3.2
Mean (M)	7.4	5.0	3.3
21	7.2	4.7
	7.1	4.4
Mean (M)	7.2	4.6
28	7.1	4.1
	7.1	3.9
Mean (M)	7.1	4.0
42	6.7	3.3
	6.5	3.0
Mean (M)	6.6	3.1
60	6.6	2.6
	6.5	2.9
Mean (M)	6.6	2.8

O_c         River water with nutrients.

O_t         River water with nutrients, and test substance (2.0 mg/L). 

O_a         River water with nutrients and sodium acetate (6.7 mg/L).

 

Table II Oxygen consumption (mg/L) and the percentages biodegradation of the test substance (BOD/ThOD) and sodium acetate (BOD/ThOD) in the Closed Bottle test.

Time (days)	Oxygen consumption (mg/L)		Biodegradation (%)
	Test substance	Acetate	Test substance	Acetate
0	0.0	0.0	0	0
7	2.0	3.4	34	65
14	2.4	4.1	41	79
21	2.6		44
28	3.1		52
42	3.5		59
60	3.8		64

 

Validity criteria fulfilled:

yes

Interpretation of results:

other: Not readily biodegradable but not persistent

Conclusions:

Substance is not considered readily biodegradable
Substance is not considered to be persistent based on >60% biodegradation on day 60 in the enhanced ready biodegradability test.

Executive summary:

Biodegradability

N-(oleyl alkyl)-1,3-propanediamine mono oleate was biodegraded by 52% at day 28 in the Closed Bottle test. In the prolonged Closed Bottle test (enhanced biodegradability test) the test substance is biodegraded by 64% at day 60. The biodegradation percentage of >60% demonstrates that test substance is completely biodegradable. Moreover, the biodegradation in excess of 60% within the 60-day test period allows classification of the test item as not persistent

Description of key information

N-(Oleyl alkyl)- 1,3-propanediamine mono oleates is the salt of Oleyldiamine (CAS no 7173-62-8) and oleic acid (CAS no. 112-80-1) and will dissociate under ambient conditions into the both constituents. Both dissociation products are readily biodegradable.

In the ready test according to OECD TG 301D (GLP, reliability 1) with N-(Oleyl alkyl)- 1,3-propanediamine mono oleates, 52% biodegradation was observed at day 28 and N-(Oleyl alkyl)- 1,3-propanediamine mono oleates can therefore not be classified as readily biodegradable. On day 60 in the prolonged test 64% biodegradation was observed and the substance can therefore be considered to be ultimately biodegradable and not persistent (Ginkel, 2018).

For a similar products, N-(Oleyl alkyl)- 1,3-propanediamine di-oleates, 61% degradation was observed at day 28 using the OECD 301F test setup (Gancet, 2004) and N-(Tallow-alkyl)-1,3 -propanediamine di-oleates, 65% degradation was observed at day 28 using the OECD 301D test setup (Ginkel, 2010).

Based on the results obtained for N-(Oleyl alkyl)- 1,3-propanediamine mono oleates and similar product it is expected that better results with N-(Oleyl alkyl)-1,3-propanediamine mono oleates can be obtained when the test would be repeated.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, fulfilling specific criteria

Type of water:

freshwater

Additional information

One ready biodegradability study has been performed with N-(Oleyl alkyl)-1,3-propanediamine mono oleate. For this substance 52% biodegradation was observed after 28 days indicating that this substance can not be considered to be readily biodegradable. After 60 days 64% biodegradation was observed in the prolonged test which indicates that this substance is not persistent.

There are also two ready biodegradability studies available with similar products. One study with N-(tallow alkyl)-1,3 -propanediamine dioleate (N-C16-C18-alkyl-(evennumbered, C18 unsaturated) propane-1,3-diaminium di[(9Z)-octadec-9-enoate] (CAS No. 1307863-78-0; old CAS No. 61791-53-5)) and one study with N-(oleyl alkyl)-1,3 -propanediamine dioleate (N-[(9Z)-octadec-9-en-1-yl] propane-1,3- diaminium di[(9Z)-octadec-9 -enoate] (CAS No. 3410 -91 -5, old CAS No. 40027 -38 -1))

The study with N-(oleyl alkyl)-1,3 -propanediamine dioleate which was performed according to OECD TG 301F (Gancet 2004, GLP, reliability 2) shows that the substance was mineralized by 61% after 28d (failing 10 day window).

The second study which was performed with N-(tallow alkyl)-1,3 -propanediamine dioleate (van Ginkel 2010, GLP, reliability 1) shows 65% degradation after 28 days.

The 10 -day window criterion was however not fulfilled in this study. The reasons for failing the 10 -day window is the composition of the test substance. The test substance is a salt of N-(tallow-alkyl)-1,3 -propanediamine and oleic acid and N-(tallow-alkyl)-1,3-propanediamine is a chemical consisting of a hydrophilic group linked to a hydrophobic moiety. In ready biodegradability tests, the two moieties of this fatty amine derivative are degraded sequentially by different micro-organisms. The time window criterion was developed for pure substances on the assumption that a compound is degraded by a single organism according to a sigmoidal growth curve in ready biodegradation tests. The degradation curve of N-(tallow-alkyl)-1,3-propanediamine oleates is the sum of the growth curves of oleate and the two moieties of N-(tallow-alkyl)-1,3-propanediamine. The biodegradability of oleate and the two moieties N-(tallow-alkyl)-1,3 -propanediamine in

the Closed Bottle test may be fully in line with the time-day window criterion when judged as separate chemicals, but this is not recognizable in the overall results of the ready biodegradation of the substance. The time-window should therefore be ignored as a pass or fail criterion for N-(tallow-alkyl)-1,3-propanediamine oleates. N-(tallow-alkyl)-1,3 -propanediamine di-oleates are therefore classified as readily biodegradable based on the biodegradation percentage of 65% at day 28.

The substances have an identical chemical structure with identical position of the functional diamine and acid groups and identical CH2-groups adjacent to these functional groups. Hence, no difference in chemical reactivity is expected for the three substances. The only difference consists of a slight difference in the composition of alkyl chain lengths, slight variations in the degree of saturation in the alkyl chain and finally a different ratio of the diamine and oleic acid. Since the majority of the alkyl chains consist of C16 to C18 units, and the unsaturated part is mainly located in the more central part of the alkyl chain, significant changes in chemical behavior and/or reactivity is not to be expected.