6-chlorohexan-2-one

Biodegradation in water: screening tests

Description of key information

Biodegradation in water ability was predicted for the test substance 6-chlorohexan-2-one (CAS no. 10226 -30 -9) using the SSS QSAR prediction model. The ready biodegradability of the test substance 6-chlorohexan-2-one was estimated as 35.659% in 3 days by using O2 consumption parameter. This result indicates that 6 -chlorohexane-2 -one was estimated to be readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The predicted data for the test compound 6-Chlorohexan-2-one(CAS No. 10226-30-9) and the study for its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

Biodegradation in water ability was predicted (SSS QSAR Prediction model, 2016) for the test substance 6-chlorohexan-2-one (CAS no. 10226 -30 -9) using the SSS QSAR predictionmodel. The ready biodegradability of the test substance 6-chlorohexan-2-one was estimated as 35.659% in 3 days by using O2 consumption parameter. This result indicates that 6 -chlorohexane-2 -one was estimated to be readily biodegradable in water.

 

A study was conducted (L. Babeu and D.D. Vaishnav, 1987) to determine the possibility of developing quantitative relationships between the physicochemical properties and biodegradation of model organic chemicals. Mixed microbial cultures capable of using 45 model organic chemicals (analytical grade) as sole carbon and energy sources were separately isolated by an enrichment culture technique. Microbial seeds for the BOD tests were prepared from the culture growth (10⁵-10⁶cells/ml) in mineral salts medium containing 100 mg/l (solid) or 100µl/l (liquid) chemical substrate. The culture was diluted (1:1) with physiological saline and incubated on a shaker (150 rpm) for 24 h prior to its use.Biodegradation of 45 model chemicals by acclimated microbes was measured separately by the BOD technique. Test chemical and 1 ml of the seed were added to 20 ml of dilution water contained in a 300-ml BOD bottle. Bottles were filled to capacity with the same water, and sealed and incubated for 20 days at 21±3°C. Each test was run in duplicate. A seed control and two or more chemical concentrations ranging from 0.4 to 3.2 mg or µl/l were employed in each test. Glucose-glutamic acid controls for assessing the dilution water quality were included. Initial and 5, 10 or 11, 14 or 15, and 20-day dissolved oxygen (DO) concentrations were determined using a YSI 54 oxygen meter equipped with a self-stirring probe. The DO concentrations in randomly selected bottles were measured by the azide modification of the iodometric method. The test BOD values showing DO depletions of at least 2 mg/1 and residual DO of at least 1mg/l were acceptable. These values were adjusted for the seed control and used for calculating the 5-day mmol BOD/mmol chemical at various chemical concentrations. Comparisons of 3 predicted BOD values with the corresponding experimental value for each chemical were made by computing percent relative standard deviation (%RSD) between predicted and measured values.ThBOD and BOD5 ± SD [mmol/mmol of chemical] of the test chemical was found to be 11.50 and 5.53 ± 0.10 respectively. 2-Octanone (100 mg/L), incubated with acclimated sewage, reached 48% of the theoretical oxygen demand in 5 days.Thus, based on percentage degradation, it can be concluded that 2-octanone is readily biodegradable in nature.

The biodegradability of test chemical 2-octanone was determined by BOD technique (DINESH D. VAISHNAVI et. al; 1987). Test chemical initial concentration of 3.2 mg/L or uL/L and 1 mL of acclimated seed were added to 20 mLof dilution water in 300-mL BOD bottles for 5 days. 5-day BOD values, in mmol BOD per mmol test chemical and corresponding percent of theoretical oxygen demand (percent ThOD) was found to be 5.53 and 48.1% respectively. Hence, the test chemical 2-octanone was found to be readily biodegradable in nature.

Study was conducted to check the biodegradability status of 2 nonanone for 5 and 20 days (USEPA HPV dossier, 1997). The 20-day value was performed in duplicate. The microbial inoculum was prepared from a mixed liquor seed water sample obtained from Kings Landing water treatment facility. The concentration of the inoculums for the study was prepared a 100 ml of the seed water to 2 liters of distilled water. The initial concentration of the test substance was 1 ml of test substance to 1 liter or reagent water. BOD was 1.77 g BOD/g of test substance BOD20 was 2.00 g BOD/g of test substance. The substance is considered to be "Readily Biodegradable" based on a BOD5/COD ratio greater than 0.5 (1.77/2.42 = 0.73).

 

Biodegradation study (USEPA HPV dossier, 1997) was carried out for 2 nonanone and the prediction is done on the basis of chemical oxygen demand. 2.42 g COD/g of test substance was found to be degraded. Thus, the test chemical 2-Nonanone was found to be readily biodegradable by Chemical Oxygen Demand (COD).

 

On the basis of above results for target and read across substance, it can be concluded that the test substance 6-chlorohexan-2-one can be expected to be readily biodegradable in nature.