Chloroacetone

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

Study period:

2020-10-23 to 2020-12-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: pre-test only without definitive test, but well-documented

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

not specified

Deviations:

no

GLP compliance:

no

Remarks:

Only a preliminary study was conducted. This preliminary study was not conducted under GLP. A main test was not conducted due to the results of the preliminary study.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

not specified

Duration of test (contact time):

14 d

Initial conc.:

51 mg/L

Based on:

ThOD

Initial conc.:

44 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: acording to guideline

Reference substance:

benzoic acid, sodium salt

Preliminary study:

The present endpoint study record addresses the preliminary study. A main test was not conducted.

Test performance:

The preliminary study revealed that the test item is toxic to aquatic microorganisms. A ready biodegradability test is technically not feasible.

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

14 d

Remarks on result:

other: no biodegradation could be detected due to toxic effect of the test item

Details on results:

The test item was found to be toxic to aquatic microorganisms. The available test methods on ready biodegradability are hence not applicable. Therefore, a main test was considered technically not feasible and scientifcally not necessary.

Table 1: Biodegradation of the toxic control

		Biodegradation [%]
		Study day
		4	7	10	14
Toxicity Control 44 mg/L test item + 30 mg/L reference item	1	0	0	0	0
	2	0	0	0	0

 

Table 2: Biodegradation of the toxic control with silicone oil

		Biodegradation [%]
		Study day
		4	7	10	14
Toxicity Control with silicone oil 44 mg/L test item + 30 mg/L reference item	1	0	0	0	0
	2	0	0	0	0

Validity criteria fulfilled:

not specified

Interpretation of results:

not readily biodegradable

Conclusions:

In a Manometric Respiratory Test according to OECD TG 301 F the test item was found to be toxic towards microorganisms of actiavted sludge (0 % biodegradation after 14 days based on ThOD). It was not possible to mitigate the toxic effects when following the recommendations of the guidelines OECD TG 301 and ISO10634. The test is therefore considered technically not feasible and the test item regarded to be not readily biodegradable.

Executive summary:

To assess the ready biodegradability of the test item a pre-study was performed in compliance with the method described in OECD TG 301 F. The test item concentration selected as appropriate was 44 mg/L. corresponding to a ThOD of 51.0 mg O2/L per test vessel. In the first test the test item was pipetted directly into the medium, the amount of inoculum used to initiate the inoculation was 4.91 mL/L (25.0 mg/L dw). In the second test a silicone oil stock solution (22 g/L test item) was prepared and 0.5 mL stock solution was pipetted directly into the medium, the amount of inoculum used to initiate the inoculation was 4.83 mL/L (29.9 mg/L dw). The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The  biodegradation rate is therefore expressed as the percentage BOD (biological oxygen demand) and was calculated for each study day. In the toxicity control containing both test item and reference item (sodium benzoate) of the first test, the biodegradation achieved 0 % after 14 days. The biodegradation of the reference item was inhibited by the test item in the toxicity control. In the toxicity control containing both test item with silicone oil and reference item (sodium benzoate) of the second test, the biodegradation achieved 0% after 14 days. The biodegradation of the reference item was inhibited by the test item in the toxicity control. As a conclusion, it was not possible to mitigate the toxic effects of the test item when following the recommendations of the guidelines OECD 301 and ISO10634.

Description of key information

In a Manometric Respiratory Test according to OECD TG 301 F the substance was found to be toxic towards microorganisms of activated sludge (0 % biodegradation after 14 days based on ThOD) (reference 5.2.1-1).

Using BIOWIN v4.1 as part of EPISuite v4.11 the test substance is determined to be readily biodegradable (reference 5.2.1-2).

Following a worst case approach, the substance is considered to be not readily biodegradable based on its inhibitory effect to aquatic microorganisms.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Key information

To assess the ready biodegradability of the test item a pre-test was performed in compliance with the method described in OECD TG 301 F. The test item concentration selected as appropriate was 44 mg/L, corresponding to a ThOD of 51.0 mg O2/L per test vessel. In the first test the test item was pipetted directly into the medium. The amount of inoculum used to initiate the inoculation was 4.91 mL/L (25.0 mg/L dw). In the second test a silicone oil stock solution (22 g/L test item) was prepared and 0.5 mL stock solution was pipetted directly into the medium, the amount of inoculum used to initiate the inoculation was 4.83 mL/L (29.9 mg/L dw). The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The  biodegradation rate is therefore expressed as the percentage BOD (biological oxygen demand) and was calculated for each study day. In the toxicity control containing both test item and reference item (sodium benzoate) of the first test, the biodegradation achieved 0 % after 14 days. The biodegradation of the reference item was inhibited by the test item in the toxicity control. In the toxicity control containing both test item with silicone oil and reference item (sodium benzoate) of the second test, the biodegradation achieved 0 % after 14 days. The biodegradation of the reference item was inhibited by the test item in the toxicity control. As a conclusion, it was not possible to mitigate the toxic effects of the test item when following the recommendations of the guidelines OECD 301 and ISO10634.

 

Supporting information

In addition, using BIOWIN v4.1 as part of EPISuite v4.11 the test substance is determined to be readily biodegradable. The substance is within the applicability domain of the model. Thus the estimation is accurate (reference 5.2.1-1).

 

Conclusion

In a pre-test according to OECD TG 301 F the substance was not biodegradable (0 % biodegradation after 14 days). This was due to the inhibitory effect of the test item. It was not possible to mitigate the toxic effects when following the recommendations of the guidelines OECD TG 301 and ISO10634. However, using EPISuite v4.11 the substance was predicted to be readily biodegradable. Following a worst case approach, the substance is considered to be not readily biodegradable based on its inhibitory effect to aquatic microorganisms.

 

 

QSAR Disclaimer

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction model

The prediction model was descriped using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.