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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:
1997-09-08 - 1998-01-12
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Duration of test (contact time):
28 d
Initial conc.:
60 µg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (DOC removal)
Value:
2
Sampling time:
1 d
Key result
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
4 d
Key result
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
8 d
Key result
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
14 d
Key result
Parameter:
% degradation (DOC removal)
Value:
3
Sampling time:
28 d
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
No degradation of the test substance was measured. The result is not due to inhibition of the bacteria (inokulum). The result of additional investigations of toxicity to bacteria (cell multiplication inhibition test with Pseudomonas putida and respiration inhibition test with activated sludge) showed that the concentration of test substance tested has no inhibitory effect to bacteria.

The pass level for ready biodégradation (70 %) was not reached.
Executive summary:

The ready biodégradation in an aerobic aqueous medium of 3-MethyIpyrazol was tested by the Modified OECD Screening Test. Mineral medium containing 60µ l/1 of the test substance was inoculated with micro - organisms from the effluent of a treatment plant (domestic sewage) and incubated in the dark at 22±2°C over 28 days period. Degradation was followed by DOC (Dissolved organic carbon) analysis at least weekly. The biodégradation was calculated by expressing the DOC removed as a percentage of the concentration initially present. No degradation of the test substance was measured. The result is not due to inhibition of the bacteria (inokulum). The result of additional investigations of toxicity to bacteria (cell multiplication inhibition test with Pseudomonas putida and respiration inhibition test with activated sludge) showed that the concentration of test substance tested has no inhibitory effect to bacteria. The pass level for ready biodégradation (70 %) was not reached.

Description of key information

No degradation of the test substance was measured.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The reported study is GLP compliant and has Klimisch score 1. 3 -Methylpyrazole is not readily biodegradable.