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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
Study period:
Jan - Feb 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Principles of method if other than guideline:
Not relevant
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Duration of test (contact time):
28 d
Initial conc.:
200 mg/L
Based on:
ThOD/L
Parameter:
% degradation (O2 consumption)
Value:
84
Sampling time:
28 d
Details on results:
60 % degradation was reached on day 7.

Table 1: Biological degradation in percent (corrected for blank O2 consumption) of ZK 56407

Day of sampling
 Test compound    Concentration expressed in theoretical O2 demand   2 6 10 14 18 22 26 29
 ZK 56407    200 mg/L   1,8 59 75,7 78,9 81,9 83,3 83,2 84
 Reference (sodium acetate)    200 mg/L   21,1 60,2 75,4 79,4 80,8 82,8 82,2 83,2
 Toxicity control (ZK 56407 + sodium acetate)    100 mg/L + 100 mg/L   19,1 60,2 78,4 81,4 81,8 82,8 83,7 83,2
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
In accordance with the OECD 301F, the test compound ZK 56407 or precisely, the
corresponding acid is readily biodegradable under the conditions of the test and it was not toxic to the microbes of activated sludge.
Executive summary:

The purpose ofthis study was to determine the ready biodegradability of Valeriansäureanhydrid (ZK 56407), which is an intermediate of the synthesis of different steroids, in the manometrie respiration test. ZK 56407 is an acid anhydride and hydrolyzes quickly to the corresponding acid. Therefore, the acid is the predominant compound available for the degradation progress. The study was conducted in agreement with the OECD test guideline no. 301F.

The test substance was incubated in an aqueous solution including nutrients with microorganisms from a municipal sewage treatment plant for 28 days (start of treatment = day 1). The nutrient solutions were made up of phosphates, magnesium sulphate, iron chloride, ammonium chloride and calcium chloride. The test substance ZK 56407 was incubated at a concentration of 200 mg theoretical oxygen demand (ThOD) per litre. Additionally, a reference substance (sodium acetate) was tested in a single set according to the same procedure, in order to verify the viability and activity of the degrading microorganisms. One further set was incubated with sodium acetate at 100 mg ThOD/L (reference substance) plus ZK 56407 at 100 mg ThOD/L representing a toxicity control. Furthermore, a blank control was tested in triplicate without any test or reference substance. The biological degradation of the test and reference substances was evaluated by measurement of the O2 consumption during the test period. O2 consumption was continuously monitored and recorded by an automated device. The O2 consumption was calculated as the percentage of total O2 that the test material could theoretically have consumed, based on the molecular formula. The blank O2 consumption was subtracted for correction.

The test compound was degraded to 84% on day 29 (28 days of incubation). 60 % degradation was reached on day 7. The reference compound sodium acetate was degraded to 83% on day 29 (28 days of incubation). 60% degradation was reached on day 6. In the toxicity control, the reference compound (sodium acetate) plus the test compound, was degraded to 83% on day 29 (28 days of incubation), which reflected the degradation in the individual sets.

Description of key information

In accordance with the OECD 301F, the test compound ZK 56407 or precisely, the

corresponding acid is readily biodegradable under the conditions of the test and it was not toxic to the microbes of activated sludge.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information