Diphosphoric acid, compound with 1,3,5-triazine-2,4,6-triamine

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:

22 November 2010 to 24 November 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted in accordance with an internationally recognised method

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: activated sludge was obtained from the aeration tank of municipal sewage treatment works, which treats predominantly domestic waste.
- Laboratory culture: on the day of collection, the sample was passed through a sieve with a mesh of 1 mm2. A sub-sample (ca. 0.25 L) was removed and centrifuged at ca. 3000 rpm for ca. 1 minute and the supernatant removed. The sample was then made up to volume with mineral salts medium (MSM) and centrifuged. This procedure was repeated twice and the sample was aerated until required. Aliquots (10 mL) of a homogenised sample of the washed activated sludge were filtered through dried (approximately 105°C) and pre-weighed Whatman GF/C filter papers. The filters were dried for at least one hour, allowed to cool and then re-weighed. The solids level in the sludge was then calculated and an appropriate volume used to inoculate the MSM to give a final suspended solids concentration of 4 mg/L.

- Method of cultivation: air-saturated ultrapure water was added to each of three, five-litre clear glass vessels followed by the volumes of each MSM stock solution required to prepare five litres of MSM. Each culture bottle was then inoculated and a magnetic stirring bar was added. The vessels were stoppered and each was placed on an electrically-operated magnetic stirrer.

- Storage conditions: the vessels were aerated, for five days, until the day of test initiation (Day 0) with a supply of air that had been treated to remove carbon dioxide by passing it through cylinders containing fused calcium chloride and Carbosorb AS.
- Storage length: 5 days
- Preparation of inoculum for exposure:
- Pretreatment: on Day 0 of the test, the pH of the 5-day old inoculated MSM was determined and adjusted with 5M HCl to 7.4 ± 0.2 as required.
- Concentration of sludge:
- Initial cell/biomass concentration:
- Water filtered: yes
- Type and size of filter used:

Duration of test (contact time):

28 d

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: standard mineral salts medium
- Additional substrate: none
- Solubilising agent: none used
- Test temperature: 22 ± 2°C
- pH: 7.4 ± 0.2
- pH adjusted: yes
- Aeration of dilution water: yes
- Suspended solids concentration: 4 mg/L


TEST SYSTEM
- Culturing apparatus: Wheaton vials (160 mL capacity) immediately sealed with silicone septa and aluminium crimp seals. The vials were incubated horizontally on an enclosed reciprocating shaker.
- Number of culture flasks/concentration: 5
- Method used to create aerobic conditions: pre-aeration
- Measuring equipment: Carbon Analyser with software and autosampler with septum piercing apparatus.
- Test performed in closed vessels: yes
- Test performed in open system: no


SAMPLING
- Sampling frequency: 0, 7, 14, 21, 28 days.
-Number replicates for analysis: TIC analysis was conducted on three cultures of each group on each sampling occasion except on the
last day of the test, when five cultures were analysed.
- Sampling method: designated cultures were injected with concentrated sodium hydroxide (nominally 7M) and shaken for a further period of approximately one hour. The content of each treated culture was allowed to stand, then carefully transferred from the culture vials to carbon analyser vials and these were then analysed.


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Inoculum plus reference substance: yes
- Inoculum plus test substance: yes
- Inoculum plus reference substance plus test substance: yes


STATISTICAL METHODS:
None required.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

The result of a preliminary solubility trial showed that the test substance was insufficiently soluble in ultrapure (UP) water to prepare a test stock. Therefore, on Day 0 of the test, the test substance (299.5 mg) was weighed into a 50 mL volumetric flask and made up to volume with CO2 free UP water. The contents of the flask were then added to the test vessel. The flask was rinsed with a further three 50 mL volumes of CO2 free water and added to the test
vessel. To ensure similarity in the preparation of all cultures, 200 mL of CO2 free UHP water was added to the control and reference vessels.

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

7 d

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

14 d

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

21 d

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

28 d

Details on results:

The production of CO2 in the control cultures, expressed as a percentage of the nominal organic carbon load of test substance was, at most, 18.8% on Day 21. There was no evidence of CO2 production by mixtures containing MPP above that evolved by the controls during the test.

Results with reference substance:

63.8% degradation in 7 days

Percent degradation of reference substance in presence of test substance:

64.9% 7 days

63.2% 14 d

63.6% 21d

61.7% 28 d

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Substances are considered to be readily biodegradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10%. As there was no evidence of CO2 production above that of the controls , MPP was considered not to be readily biodegradable under the conditions of this test.

Description of key information

MPP is not readily biodegradable in the aquatic environment.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

There was no evidence of CO2 production in test solutions containing MPP above that evolved by the controls during the test.

Substances are considered to be readily biodegradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10%. Therefore, MPP was not considered to be readily biodegradable under the conditions of this test..