1,3-difluorobenzene

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

1,3-difluorobenzene

EC Number:

206-746-5

EC Name:

1,3-difluorobenzene

Cas Number:

372-18-9

Molecular formula:

C6H4F2

IUPAC Name:

1,3-difluorobenzene

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Results and discussion

Preliminary study:

The test vessels were filled with medium, then test item and positive control were added to the appropriate vessels and the pH was measured and adjusted to 7.3 – 7.5. After pH-adjustment, the inoculum was added, the vessels were connected to the OxiTop® measuring heads and they were started via the OxiTop® Controllers.

Test performance:

The oxygen which was consumed by the content of the vessels was measured automati-cally by the test apparatus.
After 28 days, the test was ended.
Because the test item and positive control do not contain nitrogen, presence of nitrate and nitrite was not checked.

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

7.2

Sampling time:

28 d

Details on results:

The degree of biodegradation reached 0 % after 28 days.
The 10-day-window could not be detected. The pass level of 60 % given in the OECD guideline was missed.
The degradation phase is defined as interval between the end of the lag phase and the reaching of 90 %. Degradation phase could not be observed.

Any other information on results incl. tables

Table9.2‑a      pH-values on day 0 and day 28 and Oxygen demand and degradation values on day 28

Flask	Blank control 1	Blank control 2	Blank control 3	Positive control 1	Positive control 2	Positive control 3
pH at day 0	7.5	7.5	7.5	7.5	7.5	7.5
pH at day 28	7.4	7.4	7.4	7.8	7.8	7.8
Oxygen demand in mg/L at day 28	21.5	30.5	21.5	119	113	119
Oxygen demand in mg/L after deduction	--	--	--	94.5	88.5	94.5
% biological degradation	--	--	--	94.6	88.6	94.6

 

Table9.2‑b      pH-values on day 0 and day 28 and Oxygen demand and degradation values on day 28

Flask	Test item 1	Test item 2	Test item 3	Mean Test item	Abiotic Control	Toxicity Control
pH at day 0	7.5	7.5	7.5	--	7.3	7.4
pH at day 28	7.5	7.5	7.5	--	7.3	7.6
Oxygen demand in mg/L at day 28	7.2	12.6	14.4	--	0	102
Oxygen demand in mg/L after deductions	-17.3	-11.9	-10.1	--	0	77.5
% biological degradation	-17.3	-11.9	-10.1	-13.1	0	38.6

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

1,3-DIFLUOROBENZENE is therefore considered as “not readily biodegradable”. 1,3-DIFLUOROBENZENE is considered as not ultimately biodegradable, within 28 days either.