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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: screening test, other
Remarks:
inherent biodegradeability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17.02. - 17.03.1987
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to
Guideline:
other: DEV L25 (DIN 38412 Teil 25), Zahn-Wellens-Verfahren
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Deviations:
not specified
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
28 d
Initial conc.:
237 mg/L
Based on:
test mat.
Initial conc.:
100 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
aniline
Test performance:
DOC measurement

20 mL of substance were collected at each sampling point.
The concentration of dissolved organic carbon was measured at the beginning of the test period and after 3h, 1d, 7d, 14d, 21d, 27d and 28d. In the same way a blank test and a reference compound (aniline) were analyzed.
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
3 h
Parameter:
% degradation (DOC removal)
Value:
19
Sampling time:
1 d
Parameter:
% degradation (DOC removal)
Value:
17
Sampling time:
7 d
Parameter:
% degradation (DOC removal)
Value:
33
Sampling time:
14 d
Parameter:
% degradation (DOC removal)
Value:
28
Sampling time:
21 d
Parameter:
% degradation (DOC removal)
Value:
28
Sampling time:
27 d
Parameter:
% degradation (DOC removal)
Value:
30
Sampling time:
28 d
Results with reference substance:
97 % Degr. after 7 d
98 % Degr. after 14 d

DOC results of Blank, Reference solution and Test solution

Time  Blank  Reference solution        Test solution      
   DOC
[mg/L]
   DOC
[mg/L]
   DOC net
[mg/L]
 degradation
[%]
   DOC
[mg/L]
   DOC net
[mg/L]
degradation
[%] 
 0 h  16  110  94  0  109  93  0
 3 h  15  84  69  27  137  122  0
 1 d 16   91  75  20  91  75  19
 7 d  26  29  3  97  103  77  17
 14 d  24  26  2  98  86  62  28
 21 d  18  20  2  98  85  67

 28

 27 d  15  17  2  98  82  67  28
 28 d  15  18  3  97  80  65  30
Validity criteria fulfilled:
yes
Remarks:
The reference substance aniline showed a degradation of 98 % within 14 days.
Interpretation of results:
not inherently biodegradable
Conclusions:
Within 28 days, a degradation rate of 30 % was determined. The test item is considered to be "Not Inherently Biodegradable".
Executive summary:

To assess the inherent biodegradability of the substance, the concentration of dissolved organic carbon was measured at the beginning of the test period and after 3h, 1d, 7d, 14d, 21d, 27d and 28d. In the same way a blank test and a reference compound (aniline) were analyzed. Within 28 days, the substance showed a degradation rate of 30 % and is considered to be "Not Inherently Biodegradable". For the reference compound 98 % degradation was observed within 14 days. The applied method was equivalent or similar to the OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test).

Description of key information

Within 28 days a degradation rate of 30  % was determined in a study for the inherent biodegradability of the substance. The substance is considered to be "Not Inherently Biodegradable". As only 30% of the substance are degraded in the inherent test study design a "ready biodegradability" of the substance can be excluded.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

To assess the inherent biodegradability of the substance, the concentration of dissolved organic carbon was measured at the beginning of the test period and after 3h, 1d, 7d, 14d, 21d, 27d and 28d. In the same way a blank test and a reference compound (aniline) were analyzed. Within 28 days, the substance showed a degradation rate of 30 % and is considered to be "Inherently Biodegradable". For the reference compound 98 % degradation was observed within 14 days. The applied method was equivalent or similar to the OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test).