Oleonitrile

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-07-22 t/m 2009-08-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed under GLP, according guidelines with acceptable deviations, meeting quality and validity criteria

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

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:

One minor deviation from the guidelines of the Closed Bottle test was introduced; 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).

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Oleonitrile

EC Number:

204-016-0

EC Name:

Oleonitrile

Cas Number:

112-91-4

Molecular formula:

C18H33N

IUPAC Name:

(9Z)-octadec-9-enenitrile

Details on test material:

A sample of oleylnitrile was received from Akzo Nobel Surface Chemistry on 06-07-2009.
The following test substance data were submitted by the sponsor, who accepted full responsibility for the validity thereof.
• chemical name (active ingredient) oleylnitrile
• CAS reg. No. (active ingredient) 112-91-4
• Purity (see annex 2) 100%
• product name: Arneel O
• batch/lot No.: S001194
• appearance yellowish liquid
• stability not relevant
• solubility in water soluble at test concentrations
• storage at ambient temperature in the dark under nitrogen gas

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Secondary activated sludge (25-07-2009) was obtained from the wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands. This plant is an activated sludge plant treating predominantly domestic wastewater. The activated sludge was preconditioned to reduce the endogenous respiration rates. To this end, 400 mg dry weight (DW)/L of activated sludge was aerated for one week. The sludge was diluted in the BOD bottles (van Ginkel and Stroo, 1992).

Duration of test (contact time):

28 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:

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 inoculum, 10 bottles to which dichloromethane was first added and subsequently evaporated containing only inoculum, 10 bottles containing inoculum and test substance, and 6 bottles containing sodium acetate and inoculum. Accurate administration of water-insoluble
oleylnitrile at a concentration of 2.0 mg/L was accomplished by dissolving the test substance in dichloromethane (Nyholm and Seiero, 1989). The test substance in dichloromethane was directly added to bottles. Before the start of the test, the solvent was allowed to evaporate by placing the bottles on a roller bank in a ventilated hood for 24 hours to obtain an even distribution of the test substance on the walls of the bottles. The concentration of sodium acetate in the bottles was 6.7 mg/L. Each of the prepared so lutions 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 diss olved 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.

Reference substance

Reference substance:

acetic acid, sodium salt

Remarks:

purity >99% ; batch/lot No. A0206783001

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

85

Sampling time:

28 d

Details on results:

Calculated THOD oleynitrile = 3.1 mg/mg
Calculated THOD sodium acetate = 0.8 mg/mg

The validity of the test is demonstrated by an endogenous respiration of 0.9 mg/L at day 28 (Table I). Furthermore, the differences of the replicate values at day 28 were less than 20%. The biodegradation percentage of the reference compound, sodium acetate, at day 14 was 81. Finally, the validity of the test is shown by oxygen concentrations >0.5 mg/L in all bottles during the test period

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Study performed under GLP, according guidelines with acceptable deviations, meeting quality and validity criteria.
Oleylnitrile is biodegraded 85% at day 28 in the Closed Bottle test . Over 60% biodegradation was not achieved within a period of 10
days (14 days for the Closed Bottle test) immediately following the attainment of 10% biodegradation. Oleylnitrile is a poorly water soluble substance. Poor water solubility is expected to affect biodegradation kinetics because slow desorption and dissolution rates of the test substance present at high concentrations in ready biodegradability tests. It should be noted that under environmental conditions substances will be present in the environment at very low concentrations. Poor water solubility of fatty amine derivatives is therefore an important reason for not applying the time window (Richterich and Steber, 2001).
Oleylnitrile should therefore be classified as readily biodegradable

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.

Oleylnitrile did not cause a reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum. Oleylnitrile was biodegraded 85% at day 28 in the Closed Bottle test. Hence this compound should be classified as readily biodegradable. The test is valid as shown by an endogenous respiration of 0.9 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded 81% 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.