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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guidelineopen allclose all
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
according to guideline
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
Cas Number:
Molecular formula:
Test material form:
Details on test material:
White to off-white powder.
Storage Conditions: At room temperature.
Specific details on test material used for the study:
Identification: Maropitant base (CJ-11,972)
Batch (Lot) Number: 334115
Expiry date: 14 April 2020 (retest date)
Physical Description: White to off-white powder
Purity/Composition: 99.9%
Storage Conditions: At room temperature

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
The source of test organisms was activated sludge freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.

Freshly obtained sludge was kept under continuous aeration until further treatment. Before use, sludge was coarsely sieved (1 mm). After treatment concentration of suspended solids (SS) was determined to be 3.14 g/L in concentrated sludge as used for the test. Magnetically stirred sludge was used as inoculum at an amount of 3 mL per litre of mineral medium, leading to a SS concentration of 9.4 mg/L.

Reason for selection:
The test has been accepted internationally for determining 'ready' biodegradability of test items under aerobic conditions.
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
ca. 15 mg/L
Based on:
test mat.
Initial conc.:
ca. 12 mg/L
Based on:
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
Test duration : 28 days for inoculum blank and test item (last CO2 measurement on day 29).
14 days for procedural and toxicity control (last CO2 measurement on day 15).
During the test period, test media were aerated and stirred continuously.
Test vessels: 2 litre brown coloured glass bottles.
Milli- RO water: Tap-water purified by reverse osmosis (Milli- RO) and subsequently passed over activated carbon.
Stock solutions of A) 8.50 g KH2PO4
mineral components 21.75 g K2HPO4
67.20 g Na2HPO4.12H2O
0.50 g NH4Cl
dissolved in Milli- RO water and made up to 1 litre, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H2O dissolved in Milli- RO water and
made up to 1 litre.
C) 36.40 g CaCl2.2H2O dissolved in Milli- RO water and
made up to 1 litre.
D) 0.25 g FeCl3.6H2O dissolved in Milli- RO water and
made up to 1 litre.
Mineral medium 1 L mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B) to (D) and Milli- RO water.
Barium hydroxide 0.0125 M Ba(OH)2 (Boom, Meppel, The Netherlands), stored in a sealed vessel to prevent absorption of CO2 from air.
Synthetic air (CO2 < 1 ppm) A mixture of oxygen (ca. 20%) and nitrogen (ca. 80%) was passed through a bottle, containing 0.5 - 1 litre 0.0125 M Ba(OH)2 solution to trap CO2 which might be present in small amounts. Synthetic air was passed through the scrubbing solutions at a rate of approximately 1-2 bubbles per second (ca. 30-100 mL/min).
Illumination Test media were excluded from light.

Preparation of Bottles
Pre-incubation medium Before the start of the test (Day -1) mineral components, Milli- RO water (ca. 80% of final volume) and inoculum were added to each bottle. This mixture was aerated with synthetic air overnight to purge the system of CO2.
Type and number of bottles Test suspension: containing test item and inoculum (2 bottles).
Inoculum blank: containing only inoculum (2 bottles)
Procedural control: containing procedural control item and inoculum (1 bottle).
Toxicity control: containing test item, procedural control item and inoculum (1 bottle).
Preparation At the start of the test (Day 0), test and procedural control item were added to bottles containing microbial organisms and mineral components.
Volumes were made up to 2 L with Milli- RO water, resulting in the mineral medium described before.
Three CO2-absorbers (bottles filled with 100 mL 0.0125 M Ba(OH)2) were connected in series to the exit air line of each test bottle.
Reference substance
Reference substance:
acetic acid, sodium salt

Results and discussion

Preliminary study:
ThCO2 of Maropitant base (CJ-11,972) was calculated to be 3.00 mg CO2/mg.
ThCO2 of sodium acetate was calculated to be 1.07 mg CO2/mg.
% Degradationopen allclose all
% degradation (CO2 evolution)
Sampling time:
28 d
% degradation (CO2 evolution)
Sampling time:
28 d
Details on results:
Relative biodegradation values calculated from measurements performed during the test period revealed no biologically relevant biodegradation of Maropitant base (CJ-11,972) (3% and 4%, based on ThCO2).
In the toxicity control, more than 25% biodegradation occurred within 14 days (32%, based on ThCO2). Therefore, the test item was assumed not to inhibit microbial activity.
Functioning of the test system was checked by testing the procedural control item sodium acetate, which showed a normal biodegradation curve

BOD5 / COD results

Results with reference substance:
Procedural control item was biodegraded by at least 60% (actual result: 86%) within 14 days.

Any other information on results incl. tables

Temperature recorded in a vessel with water in the same room varied between 22 and 23°C, and complied with the requirements as laid down in the Study Plan. The pH values of different test vessels are presented in Table1 below

pH Values of Different Test Media

Test medium:

At the start of the test:

Day 14:

Day 28:

Blank control (A)




Blank control (B)




Procedural control




Maropitant base (CJ-11,972) (A)




Maropitant base (CJ-11,972) (B)




Toxicity control




Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
not readily biodegradable
Maropitant base (CJ-11,972) was not readily biodegradable under the conditions of the modified Sturm test presently performed.