Dihydrogen bis[P,P-dioctyl diphosphato(2-)-O'',O''''][hydroxyacetato(2-)-O1,O2]titanate(2-), branched and linear

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 - 23 Sep 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

no

Remarks:

This study was conducted in compliance with Good Laboratory Practice Standards with slight exceptions. For details please refer to the field "Any other information on Material and Methods".

Test material

Test material information

1

Reference substance name:

Dihydrogen bis[P,P-dioctyl diphosphato(2-)-O'',O''''][hydroxyacetato(2-)-O1,O2]titanate(2-), branched and linear

EC Number:

271-571-3

EC Name:

Dihydrogen bis[P,P-dioctyl diphosphato(2-)-O'',O''''][hydroxyacetato(2-)-O1,O2]titanate(2-), branched and linear

Cas Number:

68585-64-8

Molecular formula:

not applicable (UVCB substance)

IUPAC Name:

({bis[(2-ethylhexyl)oxy]phosphoryl}oxy)[(2-{[({bis[(2-ethylhexyl)oxy]phosphoryl}oxy)(hydroxy)phosphoryl]oxy}-4-oxo-1,3-dioxa-2-titanacyclopentan-2-yl)oxy]phosphinic acid; {[({bis[(2-ethylhexyl)oxy]phosphanyl}oxy)({[({bis[(2-ethylhexyl)oxy]phosphoryl}oxy)(hydroxy)phosphoryl]oxy})[(2-hydroxyacetyl)oxy]titanio]oxy}({bis[(2-ethylhexyl)oxy]phosphoryl}oxy)phosphinic acid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Easton Wastewater Treatment Facility, Easton, Maryland. Collected on September 17, 2018
- Preparation of inoculum for exposure: The sludge was sieved using a 2-mm screen and adjusted to approximately 1000 mg total suspended solids/L with mineral media and then aerated at test temperature until use.
- Initial cell/biomass concentration: 77 × 10^3 colony forming units (CFU)/mL
- Total suspended solids (TSS) measurement performed on the inoculum: 893 mg/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

10 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: 2470 mL of high grade water, 3 mL calcium chloride solution (2.75%), 3 mL of ferric chloride solution (0.025%), 3 mL of magnesium sulfate solution (2.25%) 30 mL of phosphate buffer (pH 7.4).
- Solubilising agent: Test substance was mixed with silica gel in 2:1 ratio prior to addition to the test system.
- Test temperature: 19.15-21.60 ºC
- pH: 7.4
- pH adjusted: yes
- Suspended solids concentration: A volume of activated sludge soil-amended inoculum to achieve a final TSS concentration of ≤30 mg/L.


TEST SYSTEM
- Culturing apparatus: 4-liter bottles
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: The biodegradation test was started by bubbling CO2-free air through each of the test chambers at a rate of approximately 55 mL per minute. The air entering the chambers was passed through Drierite™ to remove ambient moisture and then through Ascarite® to produce CO2-free air.
- Measuring equipment: Shimadzu Model TOC-VCSH carbon analyzer
- Test performed in closed vessels: yes
- Details of trap for CO2: The CO2 produced from the degradation of organic carbon sources within the test chamber was trapped as potassium carbonate (K2CO3) in the KOH solution and the amount of inorganic carbon in the trapping solution was measured at various intervals during the study, using a Shimadzu Model TOC-VCSH carbon analyzer.

SAMPLING
- Sampling frequency and method: On days 3, 6, 8, 11, 15, 19, 22 and 26, the CO2 trap nearest the test chamber was collected for analysis of inorganic carbon. The two remaining traps remained and a new trap was placed on the end of the series. The two remaining traps were thus one position closer to the test chamber as each new trap was added. On the 28th day of the test, an aliquot of the contents of each test chamber was removed and the pH determined. The contents of all chambers were then acidified by the addition of 1 mL of concentrated hydrochloric acid to drive off inorganic carbonate. All chambers were aerated overnight and then a sample from each test chamber was removed for dissolved organic carbon (DOC) analysis and the trapping solutions closest to the test chambers were analyzed for inorganic carbon.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3
- Reference control: 3
- Toxicity control: 1 (10 mg C/L reference substance and test substance respectively)

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

10 mg C/L

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

72.2

Sampling time:

28 d

Details on results:

- The toxicity control achieved > 25% degradation by Day 14. Therefore the substance is not considered inhibitory to sludge microorganisms at the concentration tested in this study.
- According to the “Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7b: Endpoint specific guidance” and to the Guidance “Introduction to the OECD Guidelines for Testing of Chemicals, Section 3: Degradation and Accumulation” the 10-day window is not applicable for UVCB substances.

BOD5 / COD results

Results with reference substance:

An average of 98.3% of theoretical CO2 was evolved over the test period. More than 60% biodegradation was achieved on Day 14.

Any other information on results incl. tables

According to the “Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7b: Endpoint specific guidance” and to the Guidance “Introduction to the OECD Guidelines for Testing of Chemicals, Section 3: Degradation and Accumulation” the 10-day window is not applicable for UVCB substances. Therefore the substance is considered readily biodegradable (72.2% average cumulative biodegradation within 28 d).

Table 1: Dissolved Organic Carbon (DOC) and pH of Test Solutions at Test Termination.

Test Chamber (Nominal Concentration)	DOC* (mg C/L)	pH
Control Rep. 1	1.4	7.57
Control Rep. 2	1.4	7.57
Control Rep. 3	1.3**	7.57
Sodium Benzoate Rep. 1 (10 mg C/L)	1.7	7.62
Sodium Benzoate Rep. 2 (10 mg C/L)	1.4	7.62
Sodium Benzoate Rep. 3 (10 mg C/L)	1.4	7.63
Test substance rep 1	2.3	7.53
Test substance rep 2	2.2	7.53
Test substance rep 3	2.1	7.51
Toxicity Control (10/10 mg C/L)	2.1	7.56

* Samples were filtered (0.45 µm) and acidified prior to analysis.

** Extrapolated from standard calibration curve.

Table 2: Cumulative Percent of Theoretical Carbon Dioxide Evolved.

Date	Day	Blank Control 1	Blank Control 2	Blank Control 3	Sodium Benzoate 1	Sodium Benzoate 2	Sodium Benzoate 3	Test Substance 1	Test Substance 2	Test Substance 3	Toxicity Control
23. Sep 18	3	NA	NA	NA	35.7	40.4	42	1.3	2.7	2.2	21.6
26. Sep 18	6	NA	NA	NA	64	71.2	67.4	7	9	6.6	40.2
28. Sep 18	8	NA	NA	NA	76.6	81.6	77.8	15	14.1	11.2	50.4
1-Oct-18	11	NA	NA	NA	84.9	89.4	85.4	28.8	28.8	25	62.7
5-Oct-18	15	NA	NA	NA	89.4	93.8	90.5	41.3	49.3	42.1	73.5
9-Oct-18	19	NA	NA	NA	91.7	95.7	92.8	50.1	61.1	52.2	80.1
12-Oct-18	22	NA	NA	NA	94.1	97.9	96.4	59.4	67	58.2	84
16-Oct-18	26	NA	NA	NA	94.4	98.8	99.3	65.1	74.3	62.9	87.2
19-Oct-18	29	NA	NA	NA	94.1	99.9	100.8	71.3	79.3	66.1	87.8
Cumulative Average Day 29 (n=3)					98.3			72.2			87.8
Standard Deviation					3.6			6.6

Table 3: Validity criteria for OECD 301.

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	13.2 at the end of the test	yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	Biodegradation on Day 11: 84.9 – 89.4%	yes
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	1.3 – 2.7%	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium.	18 mg CO2/L	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	Biodegradation on Day 11: 62.7%	yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Interpretation of results:

readily biodegradable

Remarks:

According to the “Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7b: Endpoint specific guidance” and to the Guidance “Introduction to the OECD Guidelines for Testing of Chemicals, Section 3: Degradation and Accumulation” the 10-day window is not applicable for UVCB substances.