4-chlorobenzophenone

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:

guideline study

Justification for type of information:

Experimental result using OECD guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

other: Mixed inoculum

Details on inoculum:

Mixed Inoculum Preparation: Polyseed capsule is a blend of broad spectrum bacteria designed specifically as seed inoculums for the BOD test. Polyseed is an EPA approved BOD seed inoculum. 15 mg of polyseed from the capsule was weighed and added in 50 ml RO water and then stirred for 1 h. This gave the bacterial count as 10+e4 to 10+e6 CFU/L. A further concentration of 1ml/L of polyseed solution is prepared and from this working inoculum 0.12 mL solution is added to every bottles of 125 ml.

Duration of test (contact time):

42 d

Initial conc.:

4 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: OECD mineral medium was used for the study
- Test temperature: 20°C
- Continuous darkness: yes
- Other: The water used in this study is deionized water

TEST SYSTEM
- Culturing apparatus: The apparatus used in this study is BOD bottles; with glass stoppers, BOD incubator & dissolved oxygen electrode and meter.



CONTROL AND BLANK SYSTEM
- Inoculum blank: it contains only test inoculum
- Procedure control: contains reference compound and inoculum
- Toxicity control: it contains test chemical, reference compound (sodium benzoate), inoculum and
mineral media
- Test system: it contains test chemical and inoculum

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

32.71

Sampling time:

42 d

Remarks on result:

other: Test substance was found to be not readily biodegradable.

Details on results:

D.O values (oxygen consumed mg O2/L) were recorded in Table 2 by using D.O meter. The amount of oxygen taken up by the microbial population during biodegradation of the test chemical was corrected for uptake by the inoculum blank control and BOD was calculated accordingly and represented in Table 3.
The BOD42 value of test chemical was observed to be 0.70 mgO2/mg. ThOD was determined by calculation as 2.14 mgO2/mg. % degradation was calculated using the values of BOD and ThOD for test item and was determined to be 32.71 % at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 55.42 % on 7th day which exceeds as 70.48 % on 42nd day. The activity of the inoculum is thus verified and the test can be considered as valid.

Results with reference substance:

The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 55.42 % on 7th day which exceeds as 70.48 % on 42nd day. The activity of the inoculum is thus verified and the test can be considered as valid.

TABLE 2: D.O VALUES (mg/L)

No. of Days	Blank Control	Test Chemical	Procedure Control(Reference Chemical)	Toxicity Control
0	8.5	8.4	8.3	8.3
7	8	5.7	4.1	2.5
14	7.8	5.3	3.2	2
21	7.4	5.1	2.5	1.4
28	7.2	4.8	1.7	0.6
35	6.5	3.9	1.3	0.5
42	6.3	3.4	1.4	0.5

 

TABLE 3 : BOD VALUES (mgO2/mg)

No. of Days	Test Chemical	Procedure Control(Reference Chemical)	Toxicity Control
0	0	0	0
7	0.55	0.92	1.32
14	0.6	1.1	1.4
21	0.55	1.17	1.45
28	0.57	1.32	1.6
35	0.62	1.25	1.45
42	0.7	1.17	1.4

 

TABLE 4: % BIODEGRADATION

 

No. of Days	Test Chemical	Procedure Control(Reference Chemical)	Toxicity Control
0	0	0	0
7	25.7	55.42	61.68
14	28.03	66.26	65.42
21	25.7	70.48	67.75
28	26.63	79.51	74.76
35	28.97	75.3	67.75
42	32.71	70.48	65.42

 

TABLE 5: BOD42, ThOD AND % BIODEGRADATION VALUES

Test System	BOD42	ThOD (mgO2/mg)	% Biodegradation
Test Chemical	0.70	2.14	32.71
Procedure Control(Reference Chemical)	1.18	1.66	70.48
Toxicity Control	1.40	2.14	65.42

 

TABLE 6: pH VALUES

No. of Days	Blank Control	Test Chemical	Procedure Control(Reference Chemical)	Toxicity Control
0	7.5	7.5	7.4	7.5
7	7.6	7.4	7.4	7.4
14	7.5	7.3	7.4	7.4
21	7.6	7.4	7.3	7.2
28	7.4	7.3	7.18	7.2
35	7.3	7.2	7.4	7.1
42	7.2	7.5	7.2	7.1

Validity criteria fulfilled:

yes

Remarks:

O2 depletion in the inoculum blank did not exceed 1.5 mg DO/L after 28 days. Residual concentration of O2 test bottles did not fall below 0.5 mg/L at any time.% degradation of reference compound has reached the pass levels (60% ThOD) by day 14.

Interpretation of results:

not readily biodegradable

Conclusions:

The test chemical undergoes 32.71 % biodegradation after 42 days in the test condition. Thus, the test item was considered to be not readily biodegradable in water.

Executive summary:

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C under aerobic conditions. The test system included control, test item, reference item and toxicity control. Polyseed were used for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 1 ml/l. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD42 value of test chemical was observed to be 0.70 mgO2/mg. ThOD was determined by calculation as 2.14 mgO2/mg. % degradation was calculated using the values of BOD and ThOD for test item and was determined to be 32.71 % at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 55.42 % on 7th day which exceeds as 70.48 % on 42nd day. The activity of the inoculum is thus verified and the test can be considered as valid. Oxygen depletion in the inoculum blank did not exceed 1.5 mg dissolved oxygen/L after 28 days. The residual conc. of oxygen in test bottles did not fall below 0.5 mg/L at any time, % degradation of reference compound has reached the pass levels (60% of ThOD) by day 14 and in a toxicity test, containing both the test substance and a reference compound, >25% biodegradation occurred within 14 days, test substance cannot be assumed to be inhibitory. Thus, fulfilling the validity crtieria as per OECD test guideline and hence, study is considered to be valid. Accordingly, the % degradation of the test chemical after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 32.71 %. Based on the results, the test chemical, under the test conditions, was considered to be not readily biodegradable in water.

 

Description of key information

The test chemical undergoes 32.71 % biodegradation after 42 days in the test condition. Thus, the test item was considered to be not readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Different experimental studies for the Biodegradation in water endpoint were reviewed for the test substance  and are summarised below:

 

The first study includes 42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical. The study was performed at a temperature of 20°C under aerobic conditions. The test system included control, test item, reference item and toxicity control. Polyseed were used for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 1 ml/l. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The BOD42 value of test chemical was observed to be 0.70 mgO2/mg. ThOD was determined by calculation as 2.14 mgO2/mg. % degradation was calculated using the values of BOD and ThOD for test item and was determined to be 32.71 % at 20 ± 1°C. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 55.42 % on 7th day which exceeds as 70.48 % on 42nd day. The activity of the inoculum is thus verified and the test can be considered as valid. Oxygen depletion in the inoculum blank did not exceed 1.5 mg dissolved oxygen/L after 28 days. The residual conc. of oxygen in test bottles did not fall below 0.5 mg/L at any time, % degradation of reference compound has reached the pass levels (60% of ThOD) by day 14 and in a toxicity test, containing both the test substance and a reference compound, >25% biodegradation occurred within 14 days, test substance cannot be assumed to be inhibitory. Thus, fulfilling the validity crtieria as per OECD test guideline and hence, study is considered to be valid. Accordingly, the % degradation of the test chemical after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 32.71 %. Based on the results, the test chemical, under the test conditions, was considered to be not readily biodegradable in water.

 

The second study includes Estimation Programs Interface Suite was run to predict the biodegradation potential of the test compound in the presence of mixed populations of environmental microorganisms. 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 biodegradability of the substance was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The half life DT50 value of test chemical was estimated to be 2.5133 months. The results indicate that the test chemical is expected to be not readily biodegradable in water. 

 

The third study of biodegradation in water was carried out. The duration of study was 28 days. Activated sludge was taken as inoculum. The concentration of sludge was taken as 30 mg/l. The concentration of test chemical was taken as 100 mg/l. The study design was of standard type. The percent biodegradation of test chemical was determined to be 4 and 0 % based on O2 consumption parameter and HPLC method respectively in duration of 28 days. As per the value of percent biodegradation the test chemical was consider as not readily biodegradable in water. 

 

The fourth  study of biodegradation in water was carried out. The duration of study was 14 days. Activated sludge was taken as inoculum. The concentration of sludge was taken as 30 mg/l. The concentration of test chemical was taken as 100 mg/l. The percent biodegradation of test chemical was determined to be 0 and 3 % based on O2 consumption parameter and GC method respectively in duration of 14 days. As per the value of percent biodegradation the test chemical was consider as not readily biodegradable in water. 

 

On the basis of the above-mentioned information, the test chemical was considered as not readily biodegradable in water.