4-phenylbenzophenone

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:

05 July to 04 August 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch No.of test material: 20161118
- Expiration date of the lot/batch: 17-11-2017
- Purity test date: 18-11-2016
- Purity: 99.74%
- Appearance: white to off white crystaline powder

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient, protected from light
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/vehicle: No data

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Waterschap Aa en Maas, s'Hertogenbosch, The Netherlands
- Preparation of inoculum for exposure: Used immediately after collection
- Pretreatment: Allowed to settle, supernatant liquid used as inoculum
- Concentration of sludge: 3.6 g/L suspended solids concentration

Duration of test (contact time):

>= 28 d

Initial conc.:

>= 13.5 mg/L

Based on:

other: Molecular formula

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
- Additional substrate:
- Solubilising agent (type and concentration if used):
- Test temperature:
- pH:
- pH adjusted: yes/no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration:
- Continuous darkness: yes/no
- Other:

TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration:
- Method used to create aerobic conditions:
- Method used to create anaerobic conditions:
- Measuring equipment:
- Test performed in closed vessels due to significant volatility of test substance:
- Test performed in open system:
- Details of trap for CO2 and volatile organics if used:
- Other:

SAMPLING
- Sampling frequency:
- Sampling method:
- Sterility check if applicable:
- Sample storage before analysis:
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 test vessels
- Positive control: 1 test vessel
- Toxicity control: 1 test vessel
- Other:

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

>= 1

Sampling time:

6 d

Parameter:

% degradation (CO2 evolution)

Value:

>= 1

Sampling time:

15 d

Parameter:

% degradation (CO2 evolution)

Value:

>= 1

Sampling time:

22 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 2

Sampling time:

28 d

Remarks on result:

other: Not readily biodegradable

Time (days)	Cumulative CO2production (mg)				Biodegradation (%)
	Inoculum blank^1	Test item^1	Positive control (Sodium acetate)	Toxicity control (Test item & sodium acetate)	Inoculum blank^1	Test item^1	Positive control (Sodium acetate)	Toxicity control (Test item & sodium acetate)
1	2.6	0.0	0.0	0.0	-	0	0	0
4	7.0	0.0	21.7	24.9	-	0	25	14
6	10.7	0.6	37.6	42.7	-	1	44	25
8	15.2	0.6	48.3	52.9	-	1	56	31
11	19.6	0.7	59.0	60.9	-	1	69	35
15	24.1	0.8	72.8	71.6	-	1	85	41
18	28.6	1.0	-	-	-	1	-	-
22	33.7	1.2	-	-	-	1	-	-
25	38.7	1.4	-	-	-	1	-	-
29	48.1*	1.6*	-	-	-	2*	-	-

Inoculum blank and test item: Microbial activity ended on day 28 by addition of HCl, but measurements taken day 29

Positive and toxicity control: Microbial activity ended on day 14 by addition of HCl, but measurements taken day 15

1            Mean of 2 test vessels

*            Mean of 3 determinations

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test substance was not readily biodegradable under the conditions of the test

Executive summary:

A study was performed to assess the ready biodegradability of the test substance according to the OECD guideline OECD 301B (CO2 evolution test (modified Sturm test), in compliance with GLP.

The test substance was incubated with microbial organisms from a domestic effluent treatment works, in a mineral medium for 28 days. Relative biodegradation was calculated from CO2 evolution measurements determined over the course of the study.

The test substance showed 2% biodegradation after 28 days, and therefore, is classified as not readily biodegradable under the conditions of the test. The positive control showed 85% biodegradation after 14 days confirming the viability of the microbial inoculum. The toxicity control showed 41% biodegradation after 14 days confirming the test substance was not inhibitory to microbial activity.

All acceptability criteria were met, therefore, this study was considered to be valid.

In conclusion, under the test conditions, the test substance was considered to be not readily biodegradable.

However, it should be noted that this study was run at a concentration of 13.5mg/L greater than the limit of solubility (0.0736mg/L) and it is unlikely that the test substance would have been available to the microbial population for biodegradation.

Description of key information

A reliable study (Klimisch 1) assessed ready biodegradability using a standard method in compliance with OECD guideline 301B, according to GLP.

After 28 days a maximum of 2% degradation was observed, therefore, the test substance should be considered as not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The test substance in a mineral medium was inoculated with secondary domestic effluent and incubated for 28 days under aerobic conditions. Biodegradation was calculated from CO2 evolution measurements determined over the course of the study. The test substance showed a maximum of 2 % degradation after 28 days. Therefore, the test substance should be considered as not readily biodegradable.

However, it should be noted that this study was run at a concentration of 13.5mg/L, based on molecular formula and is considered to be greatly over the limit of solubility (0.0736mg/L). Due to this, it is unlikely that the test substance would have been bioavailable for biodegradation by the microbes.