Decyl dihydrogen phosphate, potassium salt

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:

1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

other: See below

Details on inoculum:

Prior to use activated sludge from the sewage plant (Frankfurt/M.-Niederad) was washed twice with mineral nutrient solution (test medium) as
described in the OECD Guideline 301 B to eliminate organic and toxic components from the sludge. After resuspension in mineral nutrient
medium the sludge was aerated by means of compressed humidified air for approximately four hours then allowed to settle for 30 to 60 minutes
and filtered. The filtrate was used as inoculum (1% of the final volume of the test solution).

Duration of test (contact time):

28 d

Initial conc.:

15 mg/L

Based on:

test mat.

Initial conc.:

30 mg/L

Based on:

test mat.

Initial conc.:

60 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

The test chemical and polyvalent inoculum and mineral nutrient solution (sewage microorganisms from a sewage plant working without industrial wastes) were incubated together for a period of 28 days in the dark at 22 +/- 1 °C.
The biodegradation observed in the course of the study was determined as a percentage of the amount of CO2 that the test chemical could have
theoretically produced. This is based on the assumption that the organic carbon of the test chemical would have been quantitatively converted to
C02. For full composition see attached report.

Reference substance:

other: Sodium Benzoate

Preliminary study:

The concentrations of the test material used in the test were increased because the test material exhibited an extreme low TC02. Therefore there
were some incertainties within the first test series (performed as indicated in the Protocol of January 13th, 1992) resulting in too high degradation \values (not shown in this report) of > > 100 % within the 5 and 20 mg/l test solutions.

Test performance:

C02 evolution from the Blank flask was slightly exceeding the limits given by the EEC Guideline (50 mg C02 of total CO2 evolution within 28 d per 3 L \of test solution) but the measured value at t = 28 d (84.1 mg CO /3.5 L) is in accordance with the new DRAFT of the OECD Guideline for Testing of
Chemicals: "Ready Biodegradability" ("OECD 301 C02 Evolution Test") of June 1990 indicating a threshold of 40 mg C02 per litre of the Blank.

Parameter:

% degradation (CO2 evolution)

Value:

62.4

Sampling time:

30 d

Remarks on result:

other: 15mg/

Parameter:

% degradation (CO2 evolution)

Value:

57.6

Sampling time:

30

Remarks on result:

other: 30mg/l

Parameter:

% degradation (CO2 evolution)

Value:

75

Sampling time:

28

Remarks on result:

other: 60mg/l

Results with reference substance:

The positive control Na-Benzoate was degraded to 84.1 % within 7 d.

Biodegredation calculation

Determination of Biodegradation: Degradation was calculated as a percentage of the theoretical CO2 that should have been produced from the organic matter of the substance by complete oxidation. The CO2 being generated were calculated to the nearest 0.01 mg and biodegradation values were rounded to the nearest 0.1 percent.

0.584 mg C02/mg Test Substance= Th co2

Biodegredation therefore equals = mg Co2 produced x 100

mg of test chemical added x ThC02

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance was shown to be ready biodegradable in an OECD 301B study.

Description of key information

The substance Decyl dihydrogen phosphate, potassium salt was shown to be readily biodegradable in an OECD 301B test.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable