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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
December 21, 2012 to April 04, 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Qualifier:
according to
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Principles of method if other than guideline:
An optional toxicity control as suggested by OECD guideline 301 F was not performed. The validity of the study is not adversely affected.
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Name (as stated in the report): FRESKOMENTHE
Lot No. VE00243225
Purity: 99.2%
Expiry date 20 July, 2015
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
Duration of test (contact time):
30 d
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
A measured volume of inoculated mineral medium, containing a known concentration of test substance as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature (± 1°C) for up to 30 days. Evolved carbon dioxide is absorbed in sodium hydroxide pellets. The consumption of oxygen is determined by measuring the pressure drop in the respirometer flask. The Biological Oxygen Demand (BOD), amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidized to carbon dioxide, hydrogen to water and nitrogen to ammonium, nitrite or nitrate).

The respirometer used during this study is an Oxitop Control System, made by Wissenschaftlich-Technische Werkstätten (WTW), Weilheim, Germany.

Test substance samples (7.65 mg, corresponding to 30.0 mg/l in 255 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop, whereas the reference substance (sodium benzoate) is added as 1.00 ml of a 10.2 g/l solution in mineral medium, to give a total volume of 103 ml.

Flasks are filled with 250 ml of mineral medium (flasks containing reference substance: 100 ml). Samples of test or reference substance are added. Then suspended sludge diluted to a concentration of 1.53 g/l dry matter is added. Except when the test substance has an acid or alkaline character, the pH of each flask is not measured but assumed to be the same as the mineral medium, in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. Neutral test substances, even sodium benzoate, were shown not to affect the pH of the medium by more than 0.1 pH unit. Two sodium hydroxide pellets are placed in the quivers on top of the bottle, and the flasks are closed tightly with the measuring heads. The flasks are allowed to equilibrate to the test temperature. The measurement is started by programming the measuring unit of the Oxitop test flasks, and the test flasks are placed in the temperature controlled cupboard of the Oxitop system. After temperature equilibration, the controller of the instrument starts the data acquisition (time zero of the experiment).

Everyday the oxygen consumption of each flask is recorded and correct temperature and stirring are checked.

At the end of the test period, the pH of each flask is measured again.



Reference substance:
other: Sodium benzoate (Fluka, Buchs, Switzerland, Art. No. 71300), purity : min. 99.0%.
Remarks:
Test concentration 100 mg/L
Key result
Parameter:
% degradation (O2 consumption)
Value:
60
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
64
Sampling time:
30 d
Details on results:
Freskomenthe did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Results with reference substance:
Degradation of sodium benzoate exceeded 40% after 7 days (actual observed = 72%) and 65% after 14 days (actual observed = 84%): the activity of the inoculum was thus verified (validity criterion).

Freskomenthe undergoes 60% biodegradation after 28 days (64% after 30 days) in the test conditions. The 10-day window criterion is not fulfilled (11% biodegradation on day 9 and 49% on day 19). The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a “standard” growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted 23 March 2006), states that if a substance consists of “constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commercial forms” and “it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test.” The 10-day time-window should therefore not be applied as a pass / fail criterion for Freskomenthe, which is a mixture of two diastereoisomers. Thus, Freskomenthe should be regarded as readily biodegradable according to this test based on the biodegradation percentage of 60% at day 28.

Validity criteria fulfilled:
yes
Remarks:
The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance. Therefore, the test is considered valid.
Interpretation of results:
readily biodegradable
Conclusions:
Freskomenthe should be regarded as readily biodegradable according to this test based on the biodegradation percentage of 60% at day 28.
Executive summary:

The Ready Biodegradability of Freskomenthe was determined by the Manometric Respirometry Test.

Freskomenthe did not inhibit the intrinsic respiration of the inoculum at the test concentration and was therefore considered to be non-toxic to the inoculum at the test concentration.

Freskomenthe undergoes 60% biodegradation after 28 days (64% after 30 days) in the test conditions. The 10-day window criterion is not fulfilled (11% biodegradation on day 9 and 49% on day 19).The 10-day time window criterion was developed on the assumption that a test substance is degraded according to a “standard” growth curve in ready biodegradability tests. The OECD Guidelines for Testing of Chemicals, Section 3. Part 1: Principles and strategies related to the testing of degradation of organic chemicals (adopted 23 March 2006), states that if a substance consists of “constituents with different chain-lengths, degree and/or site of branching or stereo-isomers, even in their most purified commercial forms” and “it is anticipated that a sequential biodegradation of the individual structures is taking place, then the 10-day window should not be applied to interpret the results of the test.” The 10-day time-window should therefore not be applied as a pass / fail criterion for Freskomenthe, which is a mixture of two diastereoisomers. Thus, Freskomenthe should be regarded as readily biodegradable according to this test based on the biodegradation percentage of 60% at day 28.

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
15 December 1998 to 13 January 1999
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Name (as stated in the report): FRESKOMENTHE
Lot No. 9000317920
Purity: 97.9%
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) was used.
The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.

The dry weight of the suspended solids is determined by taking two 50 mL samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 - 110°C for two hours and weighing the residue.

Dry weight of suspended solids : 4.207 g/L
To obtain a concentration of 100 mg/L (dry weight) in a 1000 mL flask, 23.77 mL of sludge is needed (inoculum).
Duration of test (contact time):
28 d
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
A measured volume of inoculated mineral medium, containing a known concentration (30 mg/L) of test substance as the nominal sole source of organic carbon, is stirred in a closed flask at a constant temperature (± 1°C) for up to 28 days. The consumption of oxygen is determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant the gas volume in the respirometer flask. Evolved CO2 is absorbed in soda lime pellets. The amount of oxygen taken up by the microbial population during biodegradation of the test chemical (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of ThOD (Theoretical Oxygen Demand, calculated from the elemental composition, assuming that carbon is oxidised to CO2 and hydrogen to H2O).
Reference substance:
other: Sodium benzoate (purity : min. 99.0 %).
Remarks:
Reference Substance test concentration 100 mg/L
Key result
Parameter:
% degradation (O2 consumption)
Value:
84
Sampling time:
28 d
Remarks on result:
other: inherently biodegradable
Results with reference substance:
Degradation of sodium benzoate is 85 % after 7 days and 95 % after 14 days, widely in excess of the validity criterium: the activity of the inoculum is thus verified and the test is considered as valid.
Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
FRESKOMENTHE undergoes 84 % biodegradation after 28 days in the test conditions.
Thus, FRESKOMENTHE should be regarded as inherently biodegradable according to this test.

Executive summary:

The Inherent Biodegradability of FRESKOMENTHE was determined by the Manometric Respirometry Test according to the OECD Guidelines for Testing of Chemicals, Method No. 302 C.

FRESKOMENTHE undergoes 84 % biodegradation after 28 days in the test conditions.

Thus, FRESKOMENTHE should be regarded as inherently biodegradable according to this test.

Description of key information

The Ready biodegradability of Freskomenthe was studied under the stringent test conditions of the OECD 301F biodegradability screening test (Givaudan study No 12-E300, GLP. dated on April 4th, 2013). FRESKOMENTHE has been determined to be READILY Biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information