Diisononyl adipate

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Principles of method if other than guideline:

aerobic guideline: EEC Directive 79-831 Annex V, Part C, Manometric Respirometry Year: Bruessel 1984
Remark: Method is comparable to OECD guideline 301 F and ISO 9408

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Activated sludge from laboratory waste water plant Oppau, Ludwigshafen, Germany
- Concentration of dry substance in the test = 30 mg/L
- 10 mL aliquot of sludge added per test

Duration of test (contact time):

28 d

Initial conc.:

200 mg/L

Based on:

test mat.

Initial conc.:

50 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

- stock solution: 759 mg/g DOC
- concentration of test substance: 50, 100, 200 mg/l

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

> 90

Sampling time:

28 d

Details on results:

- lag phase 1 day
- degradation phase 4 days
- biodegradation degree after 28 days: >90%
- the test substance was readily biodegradable

Results with reference substance:

- Reference substance: aniline
- degradation phase 2 days
- DOC elimination 96 %
- BOD/ThOD = 75%
- lag phase 4 days

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

The test substance reached a biodegradation of > 90% in 28 days. Therefore, the test substance is readily biodegradable according to OECD criteria.

Description of key information

Readily biodegradable (according to OECD criteria): > 90% in 28 days (similar to OECD 301F)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

One study investigating the biodegradability of Diisononyl adipate is available. The study was performed under GLP conditions in a manometric respirometry test according to EU method C.4-D (equivalent to OECD 301F) (BASF 1985). Non-adapted domestic activated sludge was used as inoculum. After 28 days a biodegradation of > 90% was observed. Thus, DINA is readily biodegradable according to OECD criteria.

Based on the distribution of the UVCB primary nonyl alcohol that is used for the synthesis of DINA, the most common isomers of DINA have an C8- (~ 50%) or C7- (~ 40%) main chain. For this reason, the biodegradability of five representative structures of DINA with varyiing main chain length (linear, C7,C8) was assessed by QSAR calculations with the well established model Catabol 310B v.02.07. Isomer 1 (C8), isomer 2 (C8), isomer 4 (C7) and isomer 5 (C9) did completely fall in the applicability domain of the model. Isomer 3 (C7) was completely in the parameter domain and the metabolic domain, but 7.14% of the structural fragments were not present in the training chemicals set. Although isomer 3 was slightly out of the structural domain, the prediction is in line with the calculations for the other isomers and can yet be considered reliable.

For all isomers a biodegradation of > 70% after 28d was determined supporting the results of the available experimental study according to OECD 301F (BASF, 1985). Consequently diisononyl adipate can be considered readily biodegradable.