di-, tri- and tetrachlorotetradecane

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:

12 October until 25 November 2009

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Modified guideline study, to GLP

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

Minor deviation: Ammonium chloride was omitted from the medium to prevent oxygen consumption due to nitrification (the omission does not result in nitrogen limitation as shown by the biodegradation of the reference compound).

Qualifier:

equivalent or similar to guideline

Guideline:

ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)

Deviations:

not specified

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):Not applicable

Oxygen conditions:

aerobic

Inoculum or test system:

other: secondary activated sludge, predominantly domestic wastewater, preconditioned to reduce the endogenous respiration rates

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): wastewater treatment plant Nieuwgraaf, Duiven, The Netherlands- Pretreatment: 400 mg dry weight/l of activated sludge was aerated for 1 week- Concentration of sludge: 400 mg/l- Initial cell/biomass concentration: no data- Water filtered: no

Duration of test (contact time):

>= 28 d

Initial conc.:

ca. 2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS- Composition of medium: Water contained 8.5 mg/L KH2PO4, 21.75 mg/L K2HPO4, 33.3 mg/L Na2HPO4.2H2O, 22.5 mg/L MgSO4.7H2O, 27.5 mg/L CaCl2, 0.25 mg/L FeCl3.6H2O; sodium acetate stock solution concentration: 1.0 g/L; test substance stock suspension concentration 1.0 g/L in deionized water, prepared with polyalkoxylate alkylphenol (Agnique) and using ultrasonification (10 minutes at 200 W using a Vibra cell ultrasonic processor).- Additional substrate: Agnique- Test temperature: 22-24oC- pH: 7.0-7.1- pH adjusted: no- Aeration of dilution water: no- Suspended solids concentration: no data- Continuous darkness: yesTEST SYSTEM- Culturing apparatus: 0.3 L BOD (biological oxygen demand) test bottles - Number of culture flasks/concentration: 10- Measuring equipment: oxygen electrode (WTW Trioxmatic EO 200) and meter (WTW OXI 530)- Other: BOD test bottles were completely filled and free of air bubbles; glass stoppers were usedSAMPLING- Sampling frequency: weekly- Sampling method: from duplicate bottlesCONTROL AND BLANK SYSTEM- Inoculum blank: no- Abiotic sterile control: no- Toxicity control: not relevant- Other: 10 bottles contained only inoculum; 10 bottles contained inoculum and Agnique; 10 bottles contained inoculum and test substance suspended with Agnique; 6 bottles contained inoculum and sodium acetateSTATISTICAL METHODS: None

Reference substance:

acetic acid, sodium salt

Preliminary study:

No data

Test performance:

None reported

Parameter:

% degradation (O2 consumption)

Value:

ca. 64

Sampling time:

28 d

Remarks on result:

other: Readily biodegradable; polychlorinated tetradecane (45% chlorinated)

Details on results:

Biodegradation for the C14 chlorinated paraffin was:
0 days - 0%
7 days - 3%
14 days - 14%
21 days - 32%
28 days - 64%
42 days - 67%

Results with reference substance:

The biodegradation of the reference compound, sodium acetate, was >60% at day 7 and 71% at day 14.

Validity criteria fulfilled:

yes

Remarks:

Test validity demonstrated by oxygen concentrations of >0.5 mg/L in all bottles during the test period and by an endogenous respiration of 1.1 mg/L at day 28.

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

In a modified guideline study, to GLP, the extent of degradation of a polychlorinated tetradecane (45% chlorinated) by aerated secondary activated sludge, as measured by dissolved oxygen concentration in a Closed Bottle test, was 64% after 28 days.
It was considered that the number of bottles necessary to evaluate the 10-d window would cause the test to become too unwieldy therefore a 14-day window was used for this closed bottle test as described in the OECD 301 guideline. The degree of biodegradation reached 10% on Day 14. By Day 28 it has surpassed the 60% pass level within the 14-day window.

Executive summary:

In a GLP study, the biodegradation of a polychlorinated tetradecane (45% chlorinated) was determined by measuring oxygen consumption in a Closed Bottle test, where a concentration of 2 mg/L was incubated in the dark for at least 28 days with secondary activated sludge derived from a plant treating predominantly domestic wastewater. Test procedure deviations from OECD Guideline 301 D and EU Method C.4 -E were minor. Two duplicate bottles from each group were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, 28 and 42.

The extent of biodegradation at day 0, 7, 14, 21, 28 and 42 was 0, 3, 14, 32, 64, and 67%, respectively. Therefore, this C14 chlorinated paraffin (45% chlorination) can be considered as readily biodegradable over a 28-day period (and not persistent).

Description of key information

Readily biodegradable but failing 10 day window. Results indicate the substance is not persistant.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Type of water:

freshwater

Additional information

It was considered that the number of bottles necessary to evaluate the 10-d window would cause the test to become too unwieldy therefore a 14-day window was used for this closed bottle test as described in the OECD 301 guideline. The degree of biodegradation surpassed 10% on Day 14, by Day 28 it has surpassed the 60% pass level and thus regarded as readily biodegradable.