undecan-2-one; methyl nonyl ketone

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

Data is from peer reviewed journal

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Duration of test (contact time):

28 d

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter:

% degradation (CO2 evolution)

Value:

85.4

Sampling time:

28 d

Remarks on result:

other: Other details not known

Details on results:

Test chemical undergoes 85.4% degradation using CO2 evolution parameter in 28 days.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

The percentage degradation of test chemical was determined to be 85.4% degradation using CO2 evolution parameter in 28 days. Thus, test chemical was considered to be readily biodegradable in water.

Executive summary:

Biodegradation study was conducted for evaluating the biodegradation potential of test chemical. The study was performed in accordance with the OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions. Activated sludge was used as a test inoculum. The percentage degradation of test chemical was determined to be 85.4% degradation using CO2 evolution parameter in 28 days. Thus, test chemical was considered to be readily biodegradable in water.

Description of key information

Biodegradation study was conducted for evaluating the biodegradation potential of test chemical (A.M. Apia et. al., 2019). The study was performed in accordance with the OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions. Activated sludge was used as a test inoculum. The percentage degradation of test chemical was determined to be 85.4% degradation using CO2 evolution parameter in 28 days. Thus, test chemical was considered to be readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Various experimental studies and predicted data of the test chemical were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental study from peer reviewed journal (A.M. Apia et. al., 2019), biodegradation study was conducted for evaluating the biodegradation potential of test chemical. The study was performed in accordance with the OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions. Activated sludge was used as a test inoculum. The percentage degradation of test chemical was determined to be 85.4% degradation using CO2 evolution parameter in 28 days. Thus, test chemical was considered to be readily biodegradable in water.

 

Another biodegradation study was carried out for evaluating the percentage biodegradability of test chemical (from handbook, peer reviewed journal and authoritative databases). Activated sludge was used as test inoculums obtained from 3 treatment plants of different sizes and designs and fed by different sewage systems. Initial test substance conc. used for the study was 500 mg/l and conc. of the inoculum used was 2,500 mg/l, respectively. Warburg constant temperature respirometer was used as a test vessel. The suspended solid conc. was adjusted to 2,500 mg/l by removal of supernatant liquid or by addition of tap water. The sludge was not washed. No mineral salts were added. The sludge suspension was blended for 10 sec and 20 ml were pipetted into 125 ml Warburg flasks containing the test substance (substrate).  A control flask for measurement of endogenous respiration was included with each run. Readings were made for 24 hr at 0.5 to 5 hr interval, depending on the rate of oxygen uptake. The experimental results were plotted as accumulative oxygen uptake corrected for endogenous respiration. %ThOD of the test chemical was determined to 21.8% by activated sludge in 24 hrs. Thus, based on this, test chemical was considered to be readily biodegradable in nature.

 

In a supporting study from peer reviewed journal (Robert M. Gerhold, 1962), biodegradation experiment was carried out for evaluating the percentage biodegradability of test chemical. Activated sludge was used as test inoculums obtained from 3 treatment plants of different sizes and designs and fed by different sewage systems. Initial test substance conc. used for the study was 500 mg/l and conc. of the inoculum used was 2,500 mg/l, respectively. Test chemical (substrates) easily soluble in water were made up in 0.1 per cent concentration with distilled water and stored at 6°C until needed. Warburg constant temperature respirometer was used as a test vessel. They were modified 125 ml Erlenmeyer flasks fitted with 1.5 ml center-wells and female ground glass joints. Warburg flasks were cleaned by the following procedure: (a) flasks were rinsed once with tap water, and dried In the 103°C oven; (b) flasks were washed with two rinses of chloroform to remove fats and greases, then dried; (c) the flasks were submerged in potassium dichromate cleaning solution for 24 hr, rinsed In the same manner as the pipettes, and dried in an inverted position. Each flask received 10 ml of substrate solution or suspension delivered with a volumetric pipette. Next, 10 ml of blended sludge were added to each flask. The final concentration of substrate was 500 mg/liter. The final concentration of sludge solids was 2500 mg/liter. The control for endogenous respiration contained 10 ml of distilled water and 10 ml of adjusted sludge. Endogenous respiration was defined as the amount of accumulative O2uptake observed in the control flask containing sludge and distilled water. After 10-20 min of shaking for temperature equilibration the flasks were closed off to the atmosphere and shaken for 24 hr at 78 oscillations per min. From 9 to 16 readings were made during each experiment. The terms "percentage oxidized," or "percentage of oxidation," or "X per cent oxidized" mean the ratio of the amount of oxygen taken up by the sludge in the presence of that concentration of the substrate to the amount of oxygen required for complete oxidation of that concentration of substrate, i.e., oxidation to carbon dioxide, water, nitrate, and sulfate. This ratio is also referred to as the "percentage of total theoretical oxygen demand (ThOD)."Theoretical O2 uptake of the test chemical Methyl nonyl ketone by activated sludge was determined to be1503 mg/l. Percentage degradation of the test chemical was determined to be 26.9% by Brookside culture, 12.3% by Columbus culture and 26.2% by Hilliard culture in 24 hrs. Thus, the chemical was considered to be readily biodegradable in water.

 

For the test chemical, biodegradation study was carried out for 28 days for evaluating the percentage biodegradability of test chemical (Secondary source, 2008. The study was performed according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) under aerobic conditions. Sewage plant effluent was used as a test inoculum for the study. Sodium benzoate was used as a reference substance for the study. The test system was shown to be viable (acceptable degradation of a model substrate, sodium benzoate) and test chemical was shown not to inhibit the biological degradation of the model substrate. The percentage degradation of test chemical was determined to be 25% by using CO2 evolution parameter in 28 days. Thus, based on percentage degradation, test chemical was considered to be not readily biodegradable in water.

 

In a prediction done using Estimation Programs Interface Suite, the biodegradation potential of the test chemical in the presence of mixed populations of environmental microorganisms was predicted. The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that test chemical is expected to be readily biodegradable.

 

In an another study from peer reviewed journal and secondary source, biodegradation experiment was conducted for evaluating the biodegradation potential of test chemical. Study was performed under using M. smegmatis (bacteria) as a test inoculum. These cultures were kindly furnished by Ruth Gordon, Institute of Microbiology, Rutgers University, New Brunswick, N. J. Test medium contains (NH4)2SO4, 1.0 g; Na2CO3, 0.1 g; KH2PO4, 0.5 g; MgSO477H20, 0.2 g; CaCl2, 10 mg; FeSO4-7H20, 5 mg; MnSO4, 2 mg; Cu, 50 Mg (as CuSO4.5H20); B, 10 Ag (as H3BO3); Zn, 70 ,ug (as ZnSO4.7H20); Mo, 10 MAg (as MoO3); pH 7.0. Water washed agar was added when solid media were desired. Washed cellular suspensions were prepared from liquid cultures, using 0.067 M phosphate buffer (pH 7) as the suspension fluid and test chemical was added at 0.2% (v/v). Test chemical was estimated photometrically by means of the colorimetric reaction. The oxygen uptake (O2 uptake) by the test bacteria of test chemical in 30 mins was evaluated to be 89. Thus, the bacterial cells were able to rapidly oxidize the test chemical and hence, chemical was considered to be biodegradable in water.

 

Overall, it can be concluded that the test chemical was considered to be readily biodegradable in water.