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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
12.04.1990-10.05.1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study; some details are missing in documentation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990
Report date:
1991

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Zinc diricinoleate
EC Number:
235-911-4
EC Name:
Zinc diricinoleate
Cas Number:
13040-19-2
Molecular formula:
C18H34O3.1/2Zn
IUPAC Name:
zinc bis(12-hydroxyoctadec-9-enoate)

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Origin: Bergisch Gladbach / Refrath
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
2.37 mg/L
Based on:
act. ingr.
Initial conc.:
4.15 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
A predetermined amount of the compound is dissolved in an inorganic medium (mineral nutrient solution), providing a concentration of about 2 mg/L active substance per litre. This solution is inoculated with a small number of microorganisms from a mixed population and kept in closed bottles in the dark in a constant temperature bath at 20 +/- 1 °C. The biodegradability is followed by oxygen analysis over a 28-day period. A control with inoculum, but without test material is run parallel for determination of oxygen blanks.

Two tests are carried out with test substance concentrations of 2.37 mg/L and 4.15 mg/L. Two tests are carried out with a reference substance (sodium acetate). Concentrations: 5 mg/L and 10 mg/L.
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

% Degradation
Parameter:
other: % BOD of COD
Value:
> 95
Sampling time:
28 d

BOD5 / COD results

BOD5 / COD
Parameter:
BOD5*100/COD
Value:
> 95 other: %

Any other information on results incl. tables

Test 1 (2.37 mg/L)

   mg O2/l after x days         
   0  5  15  28
mineral nutrient solution without test material and without inoculum  9.04 9.04   9.04  8.97
mineral nutrient solution without test material but with inoculum  9.04 9.02  9.01  8.81 
mineral nutrient solution with test material and with inoculum  9.04  5.82  5.39  4.81 

Biochemical oxygen demand

 mg BOD/L after x days      
 5  15  28
 3.20  3.62  4.00

Test 2 (4.15 mg/l).

 mg O2/l after x days         
   0  5  15  28
mineral nutrient solution without test material and without inoculum  9.04 9.04   9.04  8.97
mineral nutrient solution without test material but with inoculum  9.04 9.02  9.01  8.81 
mineral nutrient solution with test material and with inoculum  9.04  3.24  2.49  2.01

Biochemical oxygen demand

 mg BOD/L after x days      
 5  15  28
 5.78 6.52  6.80

Reference substance

Test 1 (5 mg/L)

 mg O2/l after x days         
   0  5  15  28
mineral nutrient solution without test material and without inoculum  9.04 9.04   9.04  8.97
mineral nutrient solution without test material but with inoculum  9.04 9.02  9.01  8.81 
mineral nutrient solution with test material and with inoculum  9.04  6.40  6.07  5.48

Biochemical oxygen demand

 mg BOD/L after x days      
 5  15  28
 2.62  2.94  3.33

Test 2 (10 mg/L)

 mg O2/l after x days         
   0  5  15  28
mineral nutrient solution without test material and without inoculum  9.04 9.04   9.04  8.97
mineral nutrient solution without test material but with inoculum  9.04 9.02  9.01  8.81 
mineral nutrient solution with test material and with inoculum  9.04  3.47 2.70 1.47

Biochemical oxygen demand

 mg BOD/L after x days      
 5  15  28
 5.55  6.31  7.33

Biodegradability

Test substance

   % BOD of COD after x days      
  5 15 28
Conc. 2.37 mg/L 80 91  100 
Conc. 4.15 mg/L 83  93  97 
Mean 82 92 > 95

Reference substance

   % BOD of COD after x days      
  5 15 28
Conc. 5.0 mg/L 67 75 85
Conc. 10.0 mg/L 71  81  94 
Mean 69  78  90 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Executive summary:

A biodegradation screening test according to OECD Guideline 301 D was carried out with zinc diricinoleate. The test concentrations used were 2.37 and 4.15 mg/L. An effluent from an activated sludge plant was used as test organism. The biological degradability of the test substance amounts to > 95 % BOD of COD after 28 days.

The 60 % level of the biodegradation was achieved in less than 10 days after passing the 10 % degradation level. Therefore the test substance is considered as readily biodegradable.