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Biodegradation in water: screening tests

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biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From July 17, 2000 to March 16, 2001
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
GLP compliance:
Oxygen conditions:
Inoculum or test system:
activated sludge, adapted
Details on inoculum:
Concentration of sludge: 1 g dry matter
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 150 mg/L
Based on:
other: TOC
Parameter followed for biodegradation estimation:
TOC removal
Details on study design:
- Test vessel: conical Erlenmeyer flask 5 l.
- Composition of medium:
— Solution 1: KH2PO4 8,5 g/L H2O
K2HPO4 21.75 g/L H2O
Na2HPO4 2H2O 33.4 g/L H2O
NH4Cl 0.5 g/L H2O
— Solution 2: CaCl 2 2H2O 36.4 g/L H2O
— Solution 3: MgSO4 7H2O 22.5 g/L H2O
— Solution 4: FeCl 3 6H2O 0.25 g/L H2O
Add 1000 mL of deionized water:
— Solution 1: 10 mL
— Solution 2: 1 mL
— Solution 3: 1 mL
— Solution 4: 1 mL
- Test temperature: 22 ± 2 ºC
- pH: 8
- pH adjusted: yes from 6.5 to 8
- Continuous darkness: no, diffused light.

- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: continuous aeration.
Reference substance:
diethylene glycol
% degradation (TOC removal)
< 1
Sampling time:
28 d
Results with reference substance:
100% within 19 days of test period.

800 ml of mineral medium are introduced into 5 liter Erlenmeyer flask and added sufficient volumes of mother solutions of the substance (or reference) and inoculum to two separate flasks to obtain a substance concentration based on TOC equivalent to 150 mg/l and a concentration of 1 g of dry material/l .

Add the required volume of mineral medium to reach the test volume (2 l). Taken into account that 1.041 g/l of product (0.94 g/l of active substance) presents a TOC value of 143.9 mg/l, a solution of the product of 1085 mg/l it is performed (1953 mg/l of active ingredient) to obtain a value of 150 mg TOC/l.

Validity criteria fulfilled:
Interpretation of results:
other: not readily nor inherently biodegradable
The substance is not biodegradable within 28 days of test period.
Executive summary:

The substance has been tested for inherent biodegradation according to the OECD guideline 302B (1992) and Royal Decree 363/1995 (BOE no.133 of June 1995).

Biodegradation is defined as the decomposition of an organic compound by biological action of microorganisms, resulting in the disappearance of the original molecular structure and the formation of small organic molecules. The results are expressed as percentage of biodegradation at 28 days. The result obtained in this test indicates that there is not biodegradation within 28 days of test period, i.e. <1 %, based on TOC removal.

Description of key information

not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable

Additional information

No data is available about the ready biodegradability. The only data available is about the inherent biodegradation. The substance has been tested according to the guideline OECD 302B. After 28 days of test period the biodegradation recorded was less than 1%. It was confirmed that the substance is neither readily, neither inherently biodegradable.