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Environmental fate & pathways

Biodegradation in water: screening tests

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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:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
- 1 drop of effluent per liter
- 2.5 g/liter of dry matter
Duration of test (contact time):
30 d
Initial conc.:
2 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The biodegradation was observed for 30 d at 20°C in the dark. Inoculum blanks were run in parallel. O2-concentration at the beginning was ca. 9 mg/L.
Parameter:
% degradation (O2 consumption)
Value:
83
Sampling time:
30 d

related to BOD

No information is given, if the 10-day window criterion is fulfilled.

Interpretation of results:
readily biodegradable
Conclusions:
After 30d a biodegradation of adipic acid of 83% was determined.
Executive summary:

The ready biodegradability of adipic acid was tested according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test). 1 drop of effluent of a domestic sewage plant was added per Liter. The biodegradation was observed for 30 d at 20°C in the dark. Inoculum blanks were run in parallel. O2-concentration at the beginning was ca. 9 mg/L. O2-consumption was determined.

The biodegradation rate of adipic acid was determined as 83 % after 30 d.

Description of key information

The ready biodegradability of adipic acid was tested according to OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test). 1 drop of effluent of a domestic sewage plant was added per Liter. The biodegradation was observed for 30 d at 20°C in the dark. Inoculum blanks were run in parallel. O2-concentration at the beginning was ca. 9 mg/L. O2-consumption was determined.

The biodegradation rate of adipic acid was determined as 83 % after 30 d.

Adipic acid is readily biodegradable as well as inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Several screening tests on biodegradation in water are available resulting in ready biodegradability of the substance.

In a test on ready biodegradability of adipic acid conducted according to the OECD guideline 301 D (Determination of the Ready biodegradability: Closed Bottle Test) 83 % degradation was observed after 30 days (Gerike, 1979). Although, no information on the 10-day window criterion is given, and more than 70% of the test substance has been degraded indicating a potential for complete ultimate biodegradation, it is considered that the criteria for ready biodegradability are fulfilled. Based on this result the substance should be classified as readily biodegradable. The result is supported by an aerobic ready test, performed according to the national Japanese standard method comparable to the OECD TG 301 C guideline. After a period of 4 weeks more than 90% biodegradation of adipic acid was observed (MITI, 2002).

The inherent biodegradability of adipic acid was assessed according to the EU Method C.9 (Biodegradation: Zahn-Wellens Test), showing more than 90% degradation after 5 days (Zahn, 1980). Based on these results the subtsance is considered to be inherently biodegradable.

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