Tributyl phosphate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Published literature study, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Domestic activated sludge from a local treatment plant was used. The procedure used was based on the Soap and Detergent Association method from 1965.

Settled 200 ml portions of Mississippi River water was added to a series of 16-oz narrow mouth screw-cap bottles. 4 microliters of a solution containing 50 µg of Tributyl phosphate per µl of ethanol was injected into each bottle. Each bottle was sealed with a foil-lined cap, mixed and stored in the dark at room temperature. Heat-sterilised water controls were included to confirm that any decrease in the initial 1 mg/L Tributyl phosphate level was due to biodegradation and not some other physical or chemical phenomenon. A set of Positive controls were also prepared with river water and linear alkylbenzenesulfonate (LAS). Analyses were carried out by extracting s bottle and its contents with hexane (3 x x25ml). The extracts were concentrated and analysed using gas chromatography.

Duration of test (contact time):

21 wk

Initial conc.:

20 mg/L

Based on:

DOC

Details on study design:

TEST CONDITIONS
The activated sludge method is based on the Soap and Detergent Association’s semi continuous procedure using modified feed. Domestic activated sludge from a local treatment plant was used in magnetically stirred glass vessels of 1.5 L operating volume. Tributyl phosphate was tested at addition rates of 3 and 13 mg/L per 34 hour cycle. These samples were extracted with hexane (3 x 25 ml). Concentration and analysis of the extracts were performed as for the river water samples. Sampling was carried out on a one-cycle-per week basis for each ester for periods ranging from 8 to 39 weeks.
The efficiency of the analytical methods was determined by analysing mixed liquor containing known phosphate ester concentrations. Each ester was added in duplicate at three levels (2, 4 and 6 mg/L) to activated sludge (SCAS) unit. These samples were analysed as previously indicated and the concentrations found were compared to the added concentrations. The average recovery for Tributyl phosphate was 91 ± 3 %.


TEST SYSTEM
To verify that disappearance of Tributyl phosphate was not due to volatilisation, the off-gases from each unit were passed through a series of three hexane scrubbers during a complete cycle. No significant (<0.5 %/cycle) volatility losses were observed for Tributyl phosphate.

CONTROL AND BLANK SYSTEM
Positive controls were also prepared with river water and linear alkylbenzenesulfonate (LAS).

Reference substance:

other: Positive controls were also prepared with river water and linear alkylbenzenesulfonate (LAS).

Preliminary study:

No details supplied

Test performance:

The efficiency of the analytical methods was determined by analysing mixed liquor containing known phosphate ester concentrations. Each ester was added in duplicate at three levels (2, 4 and 6 mg/L) to activated sludge (SCAS) unit. These samples were analysed as previously indicated and the concentrations found were compared to the added concentrations. The average recovery for Tributyl phosphate was 91 ± 3 %.

Parameter:

% degradation (O2 consumption)

Value:

96

Sampling time:

13 wk

Remarks on result:

other: 3 mg/L

Parameter:

% degradation (O2 consumption)

Value:

56

St. dev.:

21

Sampling time:

21 wk

Remarks on result:

other: 13 mg/L

Parameter:

% degradation (CO2 evolution)

Value:

30.4

Sampling time:

7 d

Remarks on result:

other: 19.4 mg/L

Parameter:

% degradation (CO2 evolution)

Value:

90.8

Sampling time:

28 d

Remarks on result:

other: 19.4 mg/L

Details on results:

In the activated sludge study, tributylphosphate (3 mg/L) was degraded 96% in 13 weeks. At a concentration of 13 mg/L, degradation was 56% in 21 weeks. In the carbon dioxide evolution study, degradtion was found to be 30.4% in 7 days and 90.8% in 28 days.

Results with reference substance:

No details supplied

TBP showed complete primary degradation in less than 7 days. Sterile water controls showed no significant evidence of nonbiological degradation or loss. In the activated sludge study, tributylphosphate (3 mg/L) was degraded 96% in 13 weeks. At a concentration of 13 mg/L, degradation was 56% in 21 weeks. In the carbon dioxide evolution study, degradtion was found to be 30.4% in 7 days and 90.8% in 28 days.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

TBP is biodegraded by activated sludge from domestic sewage treatment plants and is readily susceptible to biodegradation in rivers by naturally occurring microbial populations. TBP contamination is not likely to become a widespread environmental problem due to it’s low aqueous solubility and moderate potential to bioaccumulate in aquatic organisms. In the activated sludge study, tributylphosphate (3 mg/L) was degraded 96% in 13 weeks. At a concentration of 13 mg/L, degradation was 56% in 21 weeks. In the carbon dioxide evolution study, degradtion was found to be 30.4% in 7 days and 90.8% in 28 days. Tributylphosphate is considered to be readily biodegradable.

Executive summary:

The biodegradation of tributylphosphate was investigated in a modified OECD screening test. In the activated sludge study, tributylphosphate (3 mg/L) was degraded 96% in 13 weeks. At a concentration of 13 mg/L, degradation was 56% in 21 weeks. In the carbon dioxide evolution study, degradtion was found to be 30.4% in 7 days and 90.8% in 28 days. Tributylphosphate is considered to be readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not supplied

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Summary of proprietary guideline study, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

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

Principles of method if other than guideline:

Not relevant

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

No details supplied

Duration of test (contact time):

28 d

Initial conc.:

3.68 mg/L

Based on:

test mat.

Details on study design:

No details supplied

Preliminary study:

No details supplied

Test performance:

No details supplied

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

15 d

Parameter:

% degradation (O2 consumption)

Value:

92

Sampling time:

28 d

Details on results:

The biodegradation of the test substance (based on BOD) was found to be 3%, 73% and 92% after 3 days, 15 days and 28 days respectively.

Results with reference substance:

No details supplied

The biodegradation of the test substance (based on BOD) was found to be 3%, 73% and 92% after 3 days, 15 days and 28 days respectively.

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of the test substance (based on BOD) was found to be 3%, 73% and 92% after 3 days, 15 days and 28 days respectively. Tributylphosphate is therefore considered to be readily biodegradable.

Executive summary:

The biodegradation of the test substance (based on BOD) was assessed in a closed bottle test and found to be 92% after 28 days. Tributylphosphate is therefore considered to be readily biodegradable.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not stated

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: English abstract of Japanese paper, documentation insufficient for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The authors report the isolation of a bacterium capable of biodegrading tributylphosphate

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

other: Pseudomonas diminuta

Details on inoculum:

No details available

Duration of test (contact time):

43 h

Initial conc.:

2 mg/L

Based on:

test mat.

Details on study design:

No details available

Preliminary study:

No details available

Test performance:

No details available

Parameter:

not specified

Value:

50

Sampling time:

2 h

Parameter:

not specified

Value:

100

Sampling time:

43 h

Details on results:

The authors report that the isolated bacterial strain was identified as Pseudomonas diminuta. Cultures were acclimitaised to phosphate esters over a period of 2 months. At a concentration of 2 ug/ml, degrdation of tributylphosphate is reported to be >50% at two hours and 1005 at 43 hours. Greatest activity is reported at 40 degrees C and 10000 CFU/ml.

Results with reference substance:

No details available

The authors report that the isolated bacterial strain was identified as Pseudomonas diminuta. Cultures were acclimitaised to phosphate esters over a period of 2 months. At a concentration of 2 ug/ml, degrdation of tributylphosphate is reported to be >50% at two hours and 1005 at 43 hours. Greatest activity is reported at 40 degrees C and 10000 CFU/ml.

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

Complete degradation of the substance was seen within 43 hourts, under the conditions of this study.

Executive summary:

The authors describe the isolation of a bacterial strain from river water capable of degrading phosphate esters. The strain was identified as Pseudomonas (new name Brevundimonas) diminuta. Acclimatised cultures of the bacteria were shown to be capable of completely degrading tributyl phosphate (initial concentration of 2 ug/ml) within 43 hours.

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not supplied

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Summary of proprietary guideline study, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Principles of method if other than guideline:

Not relevant

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

No details supplied

Duration of test (contact time):

28 d

Initial conc.:

53.3 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

DOC

Details on study design:

No details supplied

Preliminary study:

No details supplied

Test performance:

No details supplied

Parameter:

% degradation (DOC removal)

Value:

28

Sampling time:

7 d

Parameter:

% degradation (DOC removal)

Value:

78

Sampling time:

14 d

Parameter:

% degradation (DOC removal)

Value:

83

Sampling time:

21 d

Parameter:

% degradation (DOC removal)

Value:

89

Sampling time:

28 d

Details on results:

Biodegradation (based on DOC removal) was calculated to be 28% after 7 days, 78% after 14 days and 89% after 28 days. 100% degradation of the reference substance was seen within 21 days.

Results with reference substance:

No details supplied

Biodegradation (based on DOC removal) was calculated to be 28% after 7 days, 78% after 14 days and 89% after 28 days.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Biodegradation (based on DOC removal) was calculated to be 28% after 7 days, 78% after 14 days and 89% after 28 days. Tributylphosphate is therefore considered to be readily biodegradable.

Executive summary:

The biodegradation of tributylphosphate was investigated in a modified OECD screening test. Under the conditions of this study, biodegradation (based on DOC removal) was calculated to be 89% after 8 days. Tributylphosphate is therefore considered to be readily biodegradable.

Reference 5

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not supplied

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Summary of proprietary guideline study, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Principles of method if other than guideline:

Not relevant

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

No further details

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Details on study design:

No details supplied

Preliminary study:

No details supplied

Test performance:

No details supplied

Parameter:

% degradation (O2 consumption)

Value:

26.8

Sampling time:

10 d

Parameter:

% degradation (O2 consumption)

Value:

32.3

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

77.1

Sampling time:

28 d

Details on results:

Biodegradation based on oxygen consumption was calculated to be 0% (2 days), 0% (4 days), 0% (6 days), 5.1% (8 days), 26.8% (10 days), 29.7% (12 days), 32.3% (14 days), 57.3% (16 days), 66.1% (18 days), 68.8% (20 days), 70.7% (22 days), 73.9% (24 days), 75.8% (26 days) and 77.1% (28 days). 100% degradation of the reference substance was seen within 16 days.

Results with reference substance:

No details supplied

77.1% biodegradation of the test substance was seen within 28 days under the conditions of this study.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

77.1% biodegradation of the test substance was seen within 28 days under the conditions of this study. Tributylphosphate is therefore considered to be readily biodegradable.

Executive summary:

The biodegradation of the susbstance was assessed in a modified MITI test. 77.1% biodegradation of the test substance was seen within 28 days under the conditions of this study. Tributylphosphate is therefore considered to be readily biodegradable.

Reference 6

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not stated

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Published screening data for a number of chemicals, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

The authors report the biodegradation of a number of compounds according to a cultivation method

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

No details available

Duration of test (contact time):

3 d

Initial conc.:

>= 5 - <= 50 other: ppm

Based on:

test mat.

Details on study design:

No details available

Preliminary study:

No details available

Test performance:

No details available

Parameter:

% degradation (test mat. analysis)

Value:

>= 0 - <= 28

Sampling time:

3 d

Remarks on result:

other: River water

Parameter:

% degradation (test mat. analysis)

Value:

>= 0 - <= 9

Sampling time:

3 d

Remarks on result:

other: Sea water

Details on results:

At a concentration of 50 ppm, degradation of 0% was seen in river and sea water. At a concentration of 10 ppm, degradation of 3% and 0% was seen in river water and sea water respectively. At a concentration of 5 ppm, degradation in river water was 0-28% and degradation in seawater was 0-9%.

Results with reference substance:

No details available

The biodegradation of the substance over the study period of 3 days was reported to be 0 -28% in river water and 0 -9% in sea water.

Validity criteria fulfilled:

not specified

Conclusions:

The authors investigated the biodegradation of the substance in a screening test in river and sea water.

Executive summary:

The authors investigated the biodegradation of the substance in a screening test in river and sea water. The biodegradation of the substance over the study period of 3 days was reported to be 0 -28% in river water and 0 -9% in sea water

Reference 7

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not supplied

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Published study investigating the behaviour of phosphate esters in water, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Biodegradation by activated sludge

GLP compliance:

no

Remarks:

literature study

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

No details supplied

Duration of test (contact time):

48 h

Details on study design:

No details supplied

Preliminary study:

No details supplied

Test performance:

No details supplied

Parameter:

other: % degradation

Value:

100

Sampling time:

48 h

Details on results:

Primary biodegradation is reported to be intermediate (30-40% over 48 hours). Biodegradation follwoing acclimatisation was apprroaching 100% within 48 hours.

Results with reference substance:

No details supplied

 

Primary biodegradation is reported to be intermediate (30-40% over 48 hours). Biodegradation following acclimatisation was apprroaching 100% within 48 hours.

Validity criteria fulfilled:

not applicable

Conclusions:

Primary biodegradation is reported to be intermediate (30-40% over 48 hours). Biodegradation following acclimatisation was apprroaching 100% within 48 hours.

Executive summary:

The biodegradation of the substance by activated sludge was investigated. Primary biodegradation is reported to be intermediate (30-40% over 48 hours). Biodegradation following acclimatisation was approaching 100% within 48 hours.

Reference 8

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Published study investigating the degradation of organic phosphate esters, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Degradation in river water and sea water was studied for tributyl phosphate (TBP)

GLP compliance:

no

Remarks:

published study

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

Please see Table 1 for Sampling points.

Duration of test (contact time):

>= 7 - <= 15 d

Initial conc.:

20 other: ppm

Based on:

test mat.

Initial conc.:

1 other: ppm

Based on:

test mat.

Details on study design:

The degradation experiment was carried out under the aerobic condition with stirring (about 500 r.p.m.), the collected environmental waters were transferred to a glass cylindrical water container with a volume of 10 L. Tributyl phosphate was then added. The water container was held in a dark room at 20 °C. Distilled ion exchange water which had been sterilised for 30 minutes at 120 °C and 2 atmospheric pressure in an autoclave was used as the control.

100 mL of the sample water from the experimental water container was mixed with 40 mL of hexane solution for 10 minutes. The hexane solution was analytical grade for residual pesticide and ethyl acetate. After dehydration by sodium sulphuric anhydride, the extracted solution was concentrated into 5 mL using a ‘Kdernar-Danish’ concentrator. This solution was then used as the test liquid for GC-FID or GC-AFID.

Preliminary study:

No data given

Test performance:

No data given

Parameter:

% degradation (test mat. analysis)

Value:

3.3

Sampling time:

7 d

Remarks on result:

other: river water: 20 ppm

Parameter:

% degradation (test mat. analysis)

Value:

21.9

Sampling time:

14 d

Remarks on result:

other: river water: 20 ppm

Parameter:

% degradation (test mat. analysis)

Value:

100

Sampling time:

14 d

Remarks on result:

other: sea water: 1 ppm

Details on results:

Full details are tabulated below.

Results with reference substance:

Not relevant

Results are tabulated below.

(% degradation)

Test duration (d)	Water
	River (1)	River (2)	River (3)	Sea (1)	Sea (2)
	20 ppm	1 ppm
7	3.3	100	33.3		0
8				0
14	21.9	100	100	62.7	100

Validity criteria fulfilled:

not specified

Interpretation of results:

readily biodegradable

Conclusions:

Degradation of the substance varied from 0 -100% over 7 -8 days and from 21.9 -100% over 14 days. The authors note that degradation in clean sea water is slowest, and that degradation in polluted sea water is comparable to that in river water.

Executive summary:

The authors investigated the degradation of the substance in various river and sea waters over periods of 7 -14 days.

Degradation of the substance varied from 0 -100% over 7 -8 days and from 21.9 -100% over 14 days. The authors note that degradation in clean sea water is slowest, and that degradation in polluted sea water is comparable to that in river water

Reference 9

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

Not given

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Published handbook data, documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Principles of method if other than guideline:

Similar to both OECD 301C and OECD 302C

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not relevant

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Sludge sampling was taken from:
1. City Sewage – Returned sludge from sewage plant
2. Rivers, lake and sea – Surface water and soil which were in contact with the atmosphere was collected.

5 L of the filtrate from the supernatant of an activated sludge was mixed with 500 mL of the filtrate of the supernatant of a newly collected sludge. The mixture was cultured at pH 7.0 ± 1.0 after sufficient aeration. Pre-filtered air was used for aeration.
30 minutes after aeration had ceased a third of the supernatant was removed. An equal volume of dechlorinated water was added to remaining supernatant and aerated again. Synthetic sewage was then added to achieve a concentration of 0.1 (w/v)%. This procedure was repeated once every day. The culture was contained at 25 ± 2 °C.

Duration of test (contact time):

>= 14 d

Initial conc.:

30 mg/L

Based on:

test mat.

Details on study design:

The following test solutions were prepared and cultured with a pH of 7.0:
A. (Water + Test Substance) – 9 or 30 mg of test substance was placed into 300 mL of purified water
B. (Sludge + Test Substance) – 9 or 30 mg of test substance was placed into 300 mL of basal culture medium
C. (Sludge + Aniline) – 30 mg of aniline was placed into 300 mL of purified water
D. (Control Blank) – Neither aniline nor test substance was placed into 300 mL of purified water

TEST CONDITIONS
5 L of the filtrate from the supernatant of an activated sludge was mixed with 500 mL of the filtrate of the supernatant of a newly collected sludge. The mixture was cultured at pH 7.0 ± 1.0 after sufficient aeration. Pre-filtered air was used for aeration.
30 minutes after aeration had ceased a third of the supernatant was removed. An equal volume of dechlorinated water was added to remaining supernatant and aerated again. Synthetic sewage was then added to achieve a concentration of 0.1 (w/v)%. This procedure was repeated once every day. The culture was contained at 25 ± 2 °C.

The synthetic sewage contained:
Glucose, peptone and monopotassium phosphate were dissolved in dechlorination water respectively. Each concentration equalled to 5 (w/v) % and the solution was adjusted to pH 7.0 ± 1.0 with sodium hydroxide.

TEST SYSTEM
- Number of culture flasks/concentration: 4 x 300 mL containers
- Method used to create aerobic conditions: Agitation by magnetic stirrer
- Measuring equipment: Closed system oxygen consumption measuring apparatus
- Details of trap for CO2 and volatile organics if used: Absorbant for CO2 = Soda lime No. 1

CONTROL AND BLANK SYSTEM
A vessel containing neither aniline nor test substance was used as a control


STATISTICAL METHODS:

Percentage biodegradation by BOD = (BOD – B)/TOD X 100

BOD: Biochemical Oxygen Demand in (sludge + test substance)
B: Biochemical Oxygen Demand in control blank
TOD: Theoretical Oxygen Demand required when the test substance was completely oxidised.

Percentage biodegradation by TOC = (DOCw – DOCs)/ DOCw X 100

DOCs: Residual amount of total organic carbon in (sludge + test substance)
DOCw: Residual amount of total organic carbon in (water + test substance)


Percentage biodegradation by analysis for test substance = (Sw – Ss)/ Sw X 100

Ss: Residual amount of test substance in (sludge + test substance)
Sw: Residual amount of test substance in (water + test substance)

Reference substance:

aniline

Preliminary study:

No data given

Test performance:

When % biodegradations of aniline calculated by BOD value were beyond 40 % and 60 % at the 7th and 14th day, respectively, it was concluded that the test condition was valid.

Parameter:

% degradation (O2 consumption)

Value:

>= 0 - <= 41

Sampling time:

14 d

Details on results:

The biodegradation of tributylphosphate calculated by the BOD calculation under the conditions of this study is reported to be 0-41% over 14 days.

Parameter:

BOD5

Value:

> 0 - <= 41 other: % over 14 days

Results with reference substance:

No data given

The biodegradation of tributylphosphate under the conditions of this study is reported to be 0-41% over 14 days.

Validity criteria fulfilled:

yes

Remarks:

When % biodegradations of aniline calculated by BOD value were beyond 40 % at the 7th day, respectively, it was concluded that the test condition was valid.

Conclusions:

The biodegradation of tributylphosphate under the conditions of this study is reported to be 0-41% over 14 days,

Executive summary:

The biodegradation of tributylphosphate was investigated in a modified MITI test. Under the conditions of this study is reported to be 0-41% over 14 days.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater