2-hydroxy-3-phenoxypropyl methacrylate

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:

September - 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

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

14 February 2017

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3100 (Aerobic Aquatic Biodegradation)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-hydroxy-3-phenoxypropyl methacrylate

EC Number:

240-994-5

EC Name:

2-hydroxy-3-phenoxypropyl methacrylate

Cas Number:

16926-87-7

Molecular formula:

C13H16O4

IUPAC Name:

2-hydroxy-3-phenoxypropyl 2-methylprop-2-enoate

Test material form:

liquid

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Sponsor / 171512
- Expiration date of the lot/batch: 23 December 2019

Name: PHPM
Chemical name: 3-phenoxy-2-hydroxypropyl methacrylate
CAS number: 16926-87-7
Description: Light yellow to slightly amber liquid
Molecular formula: C13H16O4
Molecular Weight: 236.27 g/mol
Purity: 97.9 %
Storage Conditions: Controlled room temperature (15-25°C, below 70 RH%), protected from humidity (tight closed container)
Safety precautions: Routine safety precautions (lab coat, gloves, safety glasses, face mask) for unknown materials were applied to assure personnel health and safety.
As agreed with the Sponsor, no correction for purity of the test item was applied

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: The secondary effluent was supplied from the sewage plant for domestic sewage in Veszprém county, Hungary.
- Preparation of inoculum for exposure: The secondary effluent used for this study was allowed to settle approximately for an hour, then the decanted effluent was aerated until use (not later than an hour).
Only filtered inoculum was added to 3.38 litres of aqueous test medium.

Duration of test (contact time):

ca. 28 d

Initial test substance concentration

Initial conc.:

3 mg/L

Based on:

ThOD

Remarks:

2.03 mg O2/mg test item and on the results of the 14-d preliminary test.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
In deionised water analytical grade salts were added to prepare the following stock solutions:
a) Solution
KH2PO4: 2.125 g
K2HPO4: 5.4375 g
Na2HPO4 x 12H2O: 16.795 g
NH4Cl: 0.125 g
Deionised water: ad 250 mL

b) Solution
MgSO4 x 7 H2O: 5.625 g
Deionised water: ad 250 mL

c) Solution
CaCl2 x 2 H2O: 9.10 g
Deionised water: ad 250 mL

d) Solution
FeCl3 x 6 H2O: 0.25 g
Deionised water: ad 1000 mL
- Test temperature: 22 +- 2 °C
- pH: 7.23
- pH adjusted: no
- Aeration of dilution water: 20 minutes and allowed to stand for about 20 hours at the test temperature
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: BOD flasks
- Number of culture flasks/concentration:
10 bottles containing the test item and inoculum
10 bottles containing the reference item and inoculum (procedure control)
10 bottles containing only inoculum (inoculum control)
10 bottles containing the test item, reference item and inoculum (toxicity control)
- Measuring equipment:
The oxygen concentrations were measured with an oxygen meter with a stirring O2 electrode.
Temperature was measured continuously and registered on weekdays.

- Test performed in closed system.

SAMPLING
- Sampling frequency: Oxygen measurements were performed in duplicate on days 0, 7, 14, 21 and 28.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Only filtered inoculum was added to 3.38 litres of aqueous test medium.
- Test Item (flasks 1a and 1b)
Based on the theoretical oxygen demand (ThOD) of 2.03 mg O2/mg test item, test item stock solution* (corresponding to 10.2 mg of Test Item) was thoroughly mixed into 3.40 litres of aqueous test medium (corresponding to 3.0 mg/L test item, with a ThOD of about 6.090 mg O2/L).
* The concentration of the stock solution was: 30.0 mg/L.
- Procedure Control: Sodium benzoate (flasks 2a and 2b). Based on the theoretical oxygen demand (ThOD) of Sodium benzoate (1.67 mg O2 per mg; details on calculation are given in the guidelines), stock solution** corresponding to 12.168 mg of Sodium benzoate was mixed into 3.38 litres of aqueous test medium (corresponding to 3.6 mg/L reference item, respectively a ThOD of about 6.012 mg O2/L).
** The concentration of the stock solution was: 360 mg/L.
- Toxicity control: The Test Item* (340.0 mL) and the reference item** stock solutions (34.0 mL) were mixed into 3.40 litres of aqueous test medium corresponding to 3.0 mg/L test item (ThOD of 6.090 mg O2/L) and 3.6 mg/L reference item (ThOD of 6.012 mg O2/L).
* The concentration of the stock solution was: 30.0 mg/L.
** The concentration of the reference item stock solution was: 360 mg/L.
- Other: Microbial inoculum (0.5 mL per litre) was added to each preparation bottle.

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

34.5

Sampling time:

28 d

Details on results:

Under the test conditions the percentage biodegradation of PHPM reached a mean of 34.5 % after 28 days based on the ThOD of the test item. According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD. Therefore, the test item is considered not readily biodegradable.
The reference item Sodium benzoate was sufficiently degraded to a mean of 61.7 % after 14 days, and to a mean of 65.0 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.
In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 37.3 % biodegradation was noted within 14 days and 38.1 % biodegradation after 28 days of incubation.
According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 3.0 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.

Any other information on results incl. tables

Calculation of Results

Calculation of BOD

  

The BOD (mg O₂ per mg test item) expected after each period was calculated as follows:

(mg O₂/L of T.i. and/or R.i. - mg O₂/L of i.control) / (mg T.i. and/or R.i./L in flask) 

where:

T.i.         = test item

R.i.        = reference item,

i.control = inoculum control

Calculation of Biodegradation %

  

The percentage biodegradation of the test item and of the reference item was calculated as follows:

( ((BOD (mg O₂/mg T.i. or R.i.)) / (ThOD (mg O₂/mg T.i.) or ThOD (mg O₂/mg R.i.)) ) *100

where:

T.i.         = test item

R.i.        = reference item,

i.control = inoculum control

Dissolved Oxygen Concentrations at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.
			0	7	14	21	28
Test Item	3.0	1a 1b mean	8.7 8.7 8.70	8.5 8.2 8.35	7.5 7.6 7.55	6.2 6.1 6.15	5.6 5.4 5.50
Reference Item	3.6	2a 2b mean	8.6 8.6 8.60	4.7 4.6 4.65	4.3 4.3 4.30	3.8 3.9 3.85	3.6 3.6 3.60
Inoculumn control	-	3a 3b mean	8.7 8.7 8.70	8.6 8.6 8.60	8.2 8.0 8.10	7.7 7.9 7.80	7.6 7.6 7.60
Toxicity control	Test item : 3.0 Reference item: 3.6	4a 4b mean	8.7 8.7 8.70	4.3 4.2 4.25	3.6 3.5 3.55	3.3 3.3 3.30	3.0 2.9 2.95

Oxygen Depletion at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	mg O2/L after n days of exposure
			7	14	21	28
Test item	3.0	1a 1b	0.1 0.40	0.60 0.50	1.60 1.70	2.00 2.20
Reference item	3.6	2a 2b	3.80 3.90	3.70 3.70	3.90 3.80	3.90 3.90
Toxicity control	Test item: 3.0 Reference item: 3.6	4a 4b	4.30 4.40	4.50 4.60	4.50 4.50	4.60 4.70

oxygen depletion: (mt0 - mtx) - (mb0 - mbx), where:

 

mt0: oxygen concentration (mg/L) of test group on day 0 (1a, 2a, 4a and 1b, 2b, 4b from Table 2)

mtx: oxygen concentration (mg/L) of test group on day x (1a, 2a, 4a and 1b, 2b, 4b from Table 2)

mb0: oxygen concentration (mg/L) of inoculum blank on day 0 (mean of 3a and 3b from Table 2)

mbx: oxygen concentration (mg/L) of inoculum blank on day x (mean of 3a and 3b from Table 2)

BOD at Different Time Intervals during the Exposure Period of 28 Days

Treatment	Concentration [mg/L]	Flask No.	BOD after n days of exposure
			7	14	21	28
Test item	3.0	1a 1b	0.03 0.13	0.20 0.17	0.53 0.57	0.67 0.73
Reference item	3.6	2a 2b	1.06 1.08	1.03 1.03	1.08 1.06	1.08 1.08
Toxiciy control	Test item: 3.0 Reference item: 3.6	4a 4b	0.65 0.67	0.68 0.70	0.68 0.68	0.70 0.71

BOD = ((mgO₂/L T.i. and/or R.i. - mgO₂/L of i.control) / mg T.i. and/or R.i./L in flask) = mgO₂/mg T.i. and or R.i.

where:

T.i.         = test item

R.i.        = reference item

i.control = inoculum control

Percentage Biodegradation at Different Time Intervals during the Exposure Period of 28 Days

 

Treatment	Concentration [mg/L]	Flask No.	Percent of biodegradation after n days of exposure
			7	14	21	28
Test item	3.0	1a 1b mean	1.6 6.6 4.1	9.8 8.2 9.0	26.3 27.9 27.1	32.8 36.1 34.5
Reference item	3.6	2a 2b mean	63.3 65.0 64.2	61.7 61.7 61.7	65.0 63.3 64.2	65.0 65.0 65.0
Toxicity control	Test item: 3.0 Reference item: 3.6	4a 4b mean	35.2 36.1 35.6	36.9 37.7 37.3	36.9 36.9 36.9	37.7 38.5 38.1

Biodegradation % = ( BOD(mgO₂/mg T.i. or R.i.) / ThOD (mgO₂/mg T.i.) or ThOD (mgO₂/mg R.i.)) *100

where:

T.i.         = test item

R.i.        = reference item

i.control = inoculum control

 

ThOD of test item        = 2.03 mg O₂/mg test item

ThOD of reference item = 1.67 mg O₂/mg reference item

 

The biodegradation in the toxicity control was calculated according to the following formula:

(BOD (mgO₂/mg T.i. and R.i.)) / ([ThOD (mg O₂/mg T.i.) + ThOD(mgO₂/mg R.i.]*0.5) *100

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item (PHPM) was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

The test system was a microbial inoculum of good quality, collected from a sewage plant for domestic sewage. The sludge was allowed to settle and then aerated until use.

Under the test conditions the percentage biodegradation of PHPM reached a mean of 34.5 % after 28 days based on the ThOD of the test item. According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD. Therefore, the test item is considered not readily biodegradable.

The reference item Sodium benzoate was sufficiently degraded to a mean of 61.7 % after 14 days, and to a mean of 65.0 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.

In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 37.3 % biodegradation was noted within 14 days and 38.1 % biodegradation after 28 days of incubation.

According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 3.0 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.


The study met the validity criteria.

The test item was not considered to have significant inhibitory effects on the secondary effluent microorganisms.

Based on the results of this study, the test item is considered not readily biodegradable.

Executive summary:

The test item (PHPM) was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item Sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

 

The test system was a microbial inoculum of good quality, collected from a sewage plant for domestic sewage. The sludge was allowed to settle and then aerated until use.

 

Under the test conditions the percentage biodegradation of PHPM reached a mean of 34.5 % after 28 days based on the ThOD of the test item.According to the test guidelines the pass level for ready biodegradability is removal of 60 % ThOD. Therefore, the test item is considered not readily biodegradable.

 

The reference item Sodium benzoate was sufficiently degraded to a mean of 61.7 % after 14 days, and to a mean of 65.0 % after 28 days of incubation, based on ThOD, thus confirming the suitability of the used inoculum.

 

In the toxicity control containing both, the test item and the reference item Sodium benzoate, a mean of 37.3 % biodegradation was noted within 14 days and 38.1 % biodegradation after 28 days of incubation.

 

According to the test guidelines the test item can be assumed to be not inhibitory at the applied concentration level of 3.0 mg/L on the secondary effluent microorganisms because degradation was >25 % within 14 days.

 

 

The study met the validity criteria.

 

The test item was not considered to have significant inhibitory effectson the secondary effluent microorganisms.

 

Based on the results of this study, the test item is considered not readily biodegradable.