Phosphoric acid, mono- and di-C12-14-alkyl esters

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:

21 May 2019 to 9 October 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Remarks:

Determination of the carbon content of the test item was not conducted according to GLP. The laboratory providing the analysis was accredited with DIN EN ISO/IEC 17025:2005.

Test material

Test material information

Constituent 1

Reference substance name:

Water

EC Number:

231-791-2

EC Name:

Water

Cas Number:

7732-18-5

Molecular formula:

H2O

IUPAC Name:

Water

Constituent 2

Reference substance name:

C12-C14 alcohol

IUPAC Name:

C12-C14 alcohol

Constituent 3

Reference substance name:

Mono (C12-C14 alkyl) phosphate ester

IUPAC Name:

Mono (C12-C14 alkyl) phosphate ester

Constituent 4

Reference substance name:

Di (C12-C14 alkyl) diphosphate ester

IUPAC Name:

Di (C12-C14 alkyl) diphosphate ester

Constituent 5

Reference substance name:

Tri (C12-C14 alkyl) triphosphate ester

IUPAC Name:

Tri (C12-C14 alkyl) triphosphate ester

Constituent 6

Reference substance name:

C12-C14 alkyl pyrophosphate esters

IUPAC Name:

C12-C14 alkyl pyrophosphate esters

Constituent 7

Reference substance name:

Ortho-phosphoric acid

IUPAC Name:

Ortho-phosphoric acid

Constituent 8

Reference substance name:

unknown

Molecular formula:

unknown

IUPAC Name:

unknown

Test material form:

solid: bulk

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 1023S17201, identification details RM1004983
- Expiration date of the lot/batch: 09 July 2020
- Purity test date: 17 April 2019
- Purity:100%
- CAS number: 68412-59-9

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: stable under normal conditions
- Solubility and stability of the test substance in the solvent/vehicle: Not soluble in water water.
- Volatility: Negligible.

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): AZV Breisgauer Bucht
- Method of cultivation: collected from municipal wastewater treatment plant
- Storage conditions: Not stated
- Storage length: sampled on the 13 August 2019, test started on 15 August 2019
- Pretreatment: the sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.
- Concentration of sludge: 5.4g/L
- Water filtered: no

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

19.5 mg/L

Based on:

ThCO2

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: standard mineral medium as per guideline
- Additional substrate: none
- Solubilising agent (type and concentration if used): test item was added directly to the test vessels due to the low solubility of the test substance, using inert stainless steel foil as a carrier material.
- Test temperature: 21.6 to 22.3°C
- pH: not measured
- CEC (meq/100 g): not stated
- Aeration of dilution water: 30 to 100ml/min, determined by counting air bubbles.
- Suspended solids concentration: 30 mg/l dry solids
- Continuous darkness: not stated

TEST SYSTEM
- Culturing apparatus: flasks of at least 1.5L
- Number of culture flasks/concentration: 3 flasks
- Method used to create aerobic conditions: continuous aeration with CO2 free air, kept mixed with magnetic stirrers
- Test performed in closed vessels due to significant volatility of test substance: System was stated as sealed
- Details of trap for CO2 and volatile organics if used: 47.88g of NaOH were dissolved in 6000ml deionised water in closed vessels to produce a 0.2M NaOH solution. The CO2-free air production system consisted of an air compressor, three 1000 mL gas wash bottles filled with dry soda lime in series followed by one bottle filled with 0.1 M NaOH (sodium hydroxide). At the end of the system was one gas wash bottle filled with demineralised water, followed by an empty one to catch any drops of condensation water. A colour change of the soda lime from white to blue indicates that the CO2 absorption capacity is depleted. The CO2-free air is passed on to an air distributor with two input and 22 output channels and through PE-tubes.

SAMPLING
- Sampling frequency: 0, 4, 7, 11, 14, 21, 28 days
- Sampling method: 6ml of NaOH sampled from the first of two CO2 absorber flasks connected in line and the Inorganic Carbon determined. On day 28 2ml of 4M hydrochloric acid (HCl) was added into each reactor to release the CO2 dissolved in the water. On day 29 the IC was determined in both CO2 absorber flasks in line.
- Sterility check if applicable: not stated
- Sample storage before analysis: no information provided about delay between sampling and analysis or storage
- Analysis method: Inorganic carbon was measured with total carbon analysers (TOC-L and TOC5050A, Shimadzu) by purging the inorganic carbon with H3PO4(25%) using a non dispersive infrared (NDIR) detector.

CONTROL AND BLANK SYSTEM
- Inoculum blank: three flasks
- Abiotic sterile control: three flasks
- Toxicity control: one flask

Reference substance

Reference substance:

other: Sodium benzoate

Results and discussion

Preliminary study:

None

% Degradation

Key result

Parameter:

% degradation (CO2 evolution)

Value:

73.1

Sampling time:

28 d

Remarks on result:

other: range 65.4 to 80.5

Details on results:

- The test item reached the criterion for ready biodegradability for surfactants in detergents (60% of ThCO2 within 28 days), but did not fullfil the 10 day window (not applied to surfactants).
- The degradation extent in the toxicity control was above 25% in 14 days based on ThCO2 (67.3%).

BOD5 / COD results

Results with reference substance:

- Sodium benzoate added to the reference vessels at a corresponding concentration of 20mg/l organic carbon.
- The biodegradation of the reference compound reached the pass level of 60% ThCO2 by day 4, passing the validity criteria.

Any other information on results incl. tables

Table 1: Ultimate biodegradation after x days [% of ThCO₂]

reactor	day	0	4	7	11	14	21	28	29
7 8 9	Test flasks	0	10.7	26.4	40.8	49.2	59.7	71.4	73.4
		0	13.0	24.4	38.4	45.3	55.5	65.2	65.4
		0	7.5	26.3	41.9	52.3	70.9	80.8	80.5
mean		0	10.4	25.7	40.3	48.9	62.0	72.5	73.1
4 5 6	reference flasks	0	70.6	77.2	81.2	84.1	84.1	88.8	88.2
		0	52.7	76.3	81.5	84.0	87.8	89.5	89.6
		0	74.8	80.8	89.0	91.0	91.9	94.0	94.8
mean		0	66.1	78.1	83.9	86.4	87.9	90.8	90.9
10	Toxicity control Test item Reference item	0	40.0	50.0	61.5	67.3	73.5	80.8	83.4

 

Table 2: Mean CO₂-evolution of blank flasks after x days

Day	0	4	7	11	14	21	28	29
CO2-evolution [mg/l]	0	9.4	12.5	15.4	16.7	19.4	22.6	23.9

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The ready biodegradability of the test substance Phosphoric acid, mixed lauryl and myristyl esters was determined to be 73.1% based on ThCO2 after 28 days, fulfilling the criterion for ready biodegradability for detergents.

Executive summary:

The ready biodegradability of the test substance Phosphoric acid, mixed lauryl and myristyl esters was assessed in a study carried out according to the OECD 301B guidelines (modified sturm test) and in compliance with GLP. It should be noted that assessment of the carbon content of the test item was not conducted according to GLP, but was accredited with DIN EN ISO/IEC 17025:2005. Biodegradation was assessed using test substance at an initital ThCO2 concentration of 19.5 -20mg/l and inoculum from activated sludge from a domestic sewage works. Biodegradation was measured over a 28 day period and measured on average 73.1% biodegradation based on ThCO2 after 28 days (ranging from 65.4 to 80.5%). The 60% biodegradation threshold within the 10 day window was not achieved, however as this test substance is a surfactant, this is criteria does not apply. No signs of toxicity were found in the toxicity controls. Based on this the test substance is considered readily biodegradable.