Tris(2-ethylhexyl) phosphate

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water and sediment: simulation tests

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Non-standard, non-guideline method, limited experimental data reported.

Data source

Reference

Reference Type:

publication

Title:

Degradation of organophosphoric esters in leachate from a sea-based solid waste disposal site

Author:

Kawagoshi Y, Nakamura S, Fukunaga I

Year:

2002

Bibliographic source:

Chemosphere, 2002, 48, 219-225

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Degradation of organophosphate esters in leachate obtained from a waste-disposal site. Water and sediment were collected from "oxidation" and aeration treatment ponds. Each substance was tested in 7.5 L of water or water/sediment (600 g wwt). Control-series: autoclave-sterilised purified water (Run1), oxidation pond water (Run2), and oxidation pond water & sediment (Run3). Test bottles: oxidation pond water (Run4), and oxidation pond water & sediment (Run5), aeration pond water (Run6), aeration pond water and sediment (Run7). Degradation was followed for 80 days by GC.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Tris(2-ethylhexyl) phosphate

EC Number:

201-116-6

EC Name:

Tris(2-ethylhexyl) phosphate

Cas Number:

78-42-2

Molecular formula:

C24H51O4P

IUPAC Name:

tris(2-ethylhexyl) phosphate

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report): tris-2-ethylhexyl phosphate (TEHP)
- 0.75 mg dissolved in acetone and added to each test bottle (target nominal concentration 0.1 mg/L)

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

other: presumably adapted pond water or water-sediment from waste-disposal site

Details on source and properties of surface water:

- Details on collection (e.g. location, sampling depth, contamination history, procedure): Water and sediment from an oxidation pond and aeration pond at a waste disposal. The aeration pond had 6 mechanical aerators. The site was a sea-based landfill operation. The report refers to the collected water as leachate.
- Temperature (°C) at time of collection: Oxidation: 20 °C, Aeration: 20 °C
- pH at time of collection: Oxidation: 8.1, Aeration: 7.6
- Oxygen concentration (mg/L) initial/final: Oxidation: 3.2, Aeration: 5.5
- Dissolved organic carbon (mg/L): Oxidation: 36, Aeration: 37
- Colour: yellow-green

Details on source and properties of sediment:

- Details on collection (e.g. location, sampling depth, contamination history, procedure): Collected with water samples from oxidation and aeration ponds.

Duration of test (contact time):

80 d

Initial test substance concentration

Initial conc.:

0.1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Volume of test solution/treatment: 7.5 L
- Solubilising agent (type and concentration if used): acetone
- Test temperature: 23-26 °C
- pH: 7.4 - 8.5
- Aeration of dilution water: Run 6&7
- Suspended solids concentration: <10 mg/L
- Continuous darkness: no

TEST SYSTEM
- Number of cultures/concentration: 1
- Method used to create aerobic conditions: Run 6&7 mechanically aerated at 5 L/min
- Method used to create anaerobic conditions:

SAMPLING
- Sampling frequency: variable

CONTROL AND BLANK SYSTEM
- Inoculum blank: purified water (Run 1)
- Abiotic sterile control: oxidation pond water (Run 2) and water/sediment (Run 3)

Reference substance

Reference substance:

other: None

Results and discussion

% Degradation

% Degradation 1

% Degr.:

30

Parameter:

test mat. analysis

Sampling time:

80 d

Remarks on result:

other: Control Run 1, sterilised purified water

% Degradation 2

% Degr.:

60

Parameter:

test mat. analysis

Sampling time:

80 d

Remarks on result:

other: Control Run 2, sterilised oxidation pond water

% Degradation 3

% Degr.:

100

Parameter:

test mat. analysis

Sampling time:

80 d

Remarks on result:

other: Control Run 3, sterilised oxidation pond water/sediment

% Degradation 4

% Degr.:

100

Parameter:

test mat. analysis

Sampling time:

40 d

Remarks on result:

other: Run 4; detection limit reached

% Degradation 5

% Degr.:

100

Parameter:

test mat. analysis

Sampling time:

40 d

Remarks on result:

other: Run 5; detection limit reached

% Degradation 6

% Degr.:

100

Parameter:

test mat. analysis

Sampling time:

40 d

Remarks on result:

other: Run 6; detection limit reached

% Degradation 7

% Degr.:

100

Parameter:

test mat. analysis

Sampling time:

40 d

Remarks on result:

other: Run 7; detection limit reached

Transformation products:

not measured

Any other information on results incl. tables

Approximately 80% loss reached between 10-15 days for runs 4 -7, and 0-40% for controls over the same period. [Figure 4 of report]

The decrease in the control Runs 2&3 could have been caused by chemical reaction with compounds present in the leachate. The cause of the slow decrease in Run 1 is not known. The rate of decrease in TEHP concentration for Runs 4 -7 was higher, suggesting an additional contribution from biodegradation, but this cannot be confirmed from this experiment.

Applicant's summary and conclusion

Validity criteria

Validity criteria fulfilled:

no

Remarks:

Not conducted to a guideline method

Conclusions:

Primary biodegradation is possible, but cannot be confirmed by this experiment.