Hexyl methacrylate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2007-07-31 - 2007-10-19

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Guideline study OECD 301F, Non GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

adopted 17 July 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

Publication No L 383 A/207-211, 29 Dec 1992

Deviations:

no

GLP compliance:

no

Remarks:

The study was conducted in accordance with ISO/IEC 17025.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the aeration tank of a muncipal sewage
treatment plant, not adapted, not pre-conditioned
- Preparation of inoculum for exposure: Prior to the test the sludge was washed twice with tap water
- Concentration of sludge: 30 mg/l dry matter in the final mixture

Duration of test (contact time):

28 d

Initial conc.:

50.8 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: Composition of medium: Aerobic mineral salts medium prepared with deionised water (conductivity: <1.5 µS/cm; DOC: < 0.3 mg/L
- Solubilising agent (type and concentration if used): not used
- Test temperature: 22 +/- 0.5°C
- pH: 7.2 -7.4
- pH adjusted: not specified
- Aeration of dilution water: not specified
- Suspended solids concentration: 30 mg/L dry matter in the final mixture
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 500 mL closed glass bottles (tightly closed with BOD measuring devices) containing a total volume of test solution of 200 mL
- Number of culture flasks/concentration: 2 flasks / one concentration 50.8 mg/L
- Measuring equipment: BOD measuring devices (OxiTop WTW wissenschaftlich-Technische Werkstätten GmbH & Co. KG D-82362 Weilheim) / Shimatzu 5050 TOC-Analyzer
- Test performed in closed vessels due to significant volatility of test substance: 500 mL closed glass bottles (tightly closed with BOD measuring devices)
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: two pellets of sodium hydroxide in a butyl rubber quiver
- Other:

SAMPLING
- Sampling frequency: at the beginning and termination (28d)
- Sampling method: not specified
- Sterility check if applicable: not applicable
- Sample storage before analysis: not specified
- Other:

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2
- Abiotic sterile control: no
- Toxicity control: 1; sodium benzoate
- Other:

Reference substance:

benzoic acid, sodium salt

Remarks:

as functional control

Parameter:

% degradation (O2 consumption)

Value:

10.9

Sampling time:

2 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

52.7

Sampling time:

12 d

Remarks on result:

other: end of 10-day window

Parameter:

% degradation (O2 consumption)

Value:

65.9

Sampling time:

28 d

Details on results:

The biodegradation of n-Hexylmethacrylate reached 53 % at the end of the 10-day window.
The calculation is based on the nominal concentration of the test substance in mg/l of 50.8 and the ThOD value was 2.537 mg O2/mg test substance.

Mean of two replicates


Kinetic of test substance (in %):
= 21.7 after 4 day(s)
= 41.8 after 8 day(s)
= 52.7 after 12 day(s)
= 55.0 after 14 day(s)
= 61.2 after 21 day(s)
= 63.6 after 25 day(s)
= 65.9 after 28 day(s)

Results with reference substance:

The positive control, sodium benzoate, reached 82 % biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.
The calculated biodegradation based on DOC measurement reached 100 % for sodium benzoate.

Kinetic of test substance (in %):
= 40.8 after 1 day(s)
= 65.9 after 4 day(s)
= 79.2 after 8 day(s)
= 80.4 after 12 day(s)
= 81.6 after 14 day(s)
= 85.2 after 21 day(s)
= 88.8 after 25 day(s)
= 91.2 after 28 day(s)

In a first test series a biodegradation of n-Hexylmethacrylate of 70 % after 28 days was determined. The respective degradation percentage at the end of the 10-d window was 60%. However, the BOD in the inoculum blank was only 18 mg O₂/L after 28 days instead of the normally observed 20 -30 mgO₂/L.

Consequently, the biodegradation of the reference compound after 14 days was higher as was normally observed. Therefore, the test was repeated.

Based on the data of the individual O₂ determinations. The mean biodegradability in the manometric respiratory test of n-Hexylmethacrylate in the second series was calculated to be 66 % after 28 days.

The biodegradation of n-Hexylmethacrylate reached 53 % at the end of the 10-d window.

Biodegradation of the test substance was observed after a lag phase of about 1 day.

The positive control, sodium benzoate, reached 82 % biodegradation after 14 days, thus confirming suitability of inoculum and test conditions. The BOD in the inoculum blanks after 28 days was 23 mg O₂/L, which is in the range of the normally observed values of 20 -30 mg O₂/L.

The respective DOC concentrations at the beginning and the end of the test (after 28 days) were (in mg/L):

35.8 (based on molecular formula) and 0.60 for the test units (mean of two replicates)

<0.5 and <0.5 for the inoculum blank (mean of two replicates)

29.2 (based on molecular formula) and 0.60 for the procedure control (one replicate)

The calculated biodegradation based on DOC measurement reached 100 % for n-hexylmethacrylate and 100 % for sodium benzoate. Due to a vapor pressure of 0.24 hPa, it cannot be excluded that some test material was removed from the test solution by evaporation.

n-Hexylmethacrylate did not reach the pass level of 60 % for ready biodegradability in the manometric respirometry test within the 10-d window and, therefore, cannot be termed as readily biodegradable . However, the pass level was reached after 28 days of incubation.

Validity criteria fulfilled:

yes

Remarks:

based on results of the blank and the sodium benzoate control

Interpretation of results:

readily biodegradable, but failing 10-day window

Remarks:

(according to REACH, RIP 3.3, part 3) the pass level of 60% ThOD was fullfild but not the 10-day window (53% after 10 days)

Conclusions:

In a guideline study (OECD 301 F, manometric respiratory test), 52.7 % biodegradation was obtained after 10 days. Therefore n-hexyl methacrylate cannot be termed as readily biodegradable. However, the pass level was reached after 28 days of incubation, thus it can be termed as inherently biodegradable (according to REACH, Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7b, Version 3.0 2016).
However, due to methodological deficiencies in terms of physical and chemical properties of the test item ( low solubility and volatile) another approach would have been more suitable. Thus, this study has to be regarded as Klimisch 3.

Executive summary:

In a valid guideline study according to OECD 301 F (manometric respiratory test) n- hexyl methacrylate was exposed to microorganisms derived from activated sludge of a muncipal sewage treatment plant under aerobic static conditions. The biodegradability of n-hexyl methacrylate was determined to be 82 % after 28 days based on O₂ consumption as compared to the theoretical O₂ demand (ThOD). Since n-hexyl methacrylate reached 53% of degradation at the end of the 10-d window, it did not reached the pass level of 60 % for ready biodegradability. The pass level of 60% ThOD was fulfilled but not the 10-day window (53% after 10 days) in the Manometric Respiratory Test. Therefore n-hexyl methacrylate is classified as not ready biodegradable, but inherently biodegradable (according to REACH, Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7b, Version 3.0 2016).

The positive control sodium benzoate reached 82 % biodegradation after 14 days, confirming of suitability of inoculum and test conditions.

However, due to methodological deficiencies in terms of physical and chemical properties of the test item ( low solubility and volatile) another approach would have been more suitable. Thus, this study has to be regarded as Klimisch 3.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Reference 2

Endpoint:

biodegradation in water: screening test, other

Remarks:

EPIWIN prediction

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

2017-05-12

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

1. SOFTWARE
Estimation Programs Interface (EPI) SuiteTM
(Developed by the US Environmental Protection Agency's Office of Pollution Prevention and Toxics and Syracuse Research Corporation (SRC). )

2. MODEL (incl. version number)
BIOWIN (v4.10)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES : O=C(OCCCCCC)C(=C)C
CHEM  : 2-Propenoic acid, 2-methyl-, hexyl ester
MOL FOR: C10 H18 O2
MOL WT : 170.25


4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL

EPI Suite™ is a screening-level tool and should not be used if acceptable measured values are available.
EPI Suite™ is a peer reviewed prediction program.
EPA's Office of Pollution Prevention and Toxics (OPPT) requested that the EPA Science Advisory Board (SAB) review the supporting science, functionality, and appropriate use of software known as the Estimation Programs Interface (EPI) Suite. OPPT has supported the development of this software for estimating the behavior of chemical substances in a biological or environmental system based on their physical, chemical and environmental properties. EPI Suite is routinely used in evaluating new chemicals under EPA's Premanufacture Notices (PMNs) for new chemicals under section 5 of the Toxic Substances Control Act, and is widely used for predicting physical/chemical properties and environmental fate and transport properties for chemicals already in commerce.

5. APPLICABILITY DOMAIN
EPI SuiteTM cannot be used for all chemical substances. The intended application domain is organic chemicals. Inorganic and organometallic chemicals generally are outside the domain.

Qualifier:

no guideline required

Version / remarks:

EPEWIN prediction

Principles of method if other than guideline:

- A biodegradability was calculated using the BIOWIN v4.10 Results model within EPI Suite ver. 4.10 (US-EPA, 2008)

GLP compliance:

no

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks on result:

readily biodegradable based on QSAR/QSPR prediction

BIOWIN (v4.10) Program Results:

==============================

SMILES : O=C(OCCCCCC)C(=C)C

CHEM  : 2-Propenoic acid, 2-methyl-, hexyl ester

MOL FOR: C10 H18 O2

MOL WT : 170.25

--------------------------- BIOWIN v4.10 Results ----------------------------

 

Biowin3 (Ultimate Biodegradation Timeframe):        Days-Weeks

Biowin5 (MITI Linear Model Prediction):               Biodegrades Fast

Ready Biodegradability Prediction:                          YES

 

 

Ready Biodegradability Prediction: (YES or NO)

Criteria for the YES or NO prediction: If the Biowin3 (ultimate survey model) result is "weeks" or faster (i.e. "days", "days to weeks", or "weeks" AND the Biowin5 (MITI linear model) probability is >= 0.5, then the prediction is YES (readily biodegradable). If this condition is not satisfied, the prediction is NO (not readily biodegradable). This method is based on application of Bayesian analysis to ready biodegradation data (see Help

 

Tables:

TYPE	NUM	Biowin3 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag	1	Linear C4 terminal chain [CCC-CH3]	0.2983	0.2983
Frag	1	Ester  [-C(=O)-O-C]	0.1402	0.1402
MolWt	*	Molecular Weight Parameter		-0.3762
Const	*	Equation Constant		3.1992
RESULT		Biowin3 (Survey Model - Ultimate Biodeg)		3.2615

Result Classification:  5.00 -> hours    4.00 -> days   3.00 -> weeks

(Primary & Ultimate)   2.00 -> months   1.00 -> longer

 

TYPE	NUM	Biowin5 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag	1	Ester  [-C(=O)-O-C]	0.3437	0.3437
Frag	2	Methyl [-CH3]	0.0004	0.0008
Frag	5	-CH2- [linear]	0.0494	0.2471
Frag	2	-C=CH [alkenyl hydrogen]	0.0062	0.0124
MolWt	*	Molecular Weight Parameter		-0.5065
Const	*	Equation Constant		0.7121
RESULT		Biowin5 (MITI Linear Biodeg Probability)		0.8097

A Probability Greater Than or Equal to 0.5 indicates --> Readily Degradable

A Probability Less Than 0.5 indicates --> NOT Readily Degradable

Validity criteria fulfilled:

not applicable

Interpretation of results:

readily biodegradable

Conclusions:

According to a BIOWIN calculation the test item n-Hexylmethacrylate is preicted to be readily biodegradable.

Executive summary:

According to a BIOWIN calculation the test item n-Hexylmethacrylate is predicted to be readily biodegradable.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

1999-11-02 - 2000-12-11

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: test procedure not vaild for volative substances

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:

activated sludge, non-adapted

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Value:

28

Sampling time:

28 d

Validity criteria fulfilled:

yes

Conclusions:

Because of the volatile properties of the test substance it is assumed that material evaporateted from the test solution and led to the obsorved low biodegradation of 28% after 28 days.
Due to this methodological deficiencies the study has to be regarded as non reliable to asssess the biodegradability of n- hexylmethacrylate.

Executive summary:

Because of the volatile properties of the test substance it is assumed that material evaporateted from the test solution and led to the obsorved low biodegradation of 28% after 28 days.

Due to this methodological deficiencies the study has to be regarded as non reliable to asssess the biodegradability of n- hexylmethacrylate.

Description of key information

The biodegradation of n-Hexyl methacrylate reached 66% after 28 days, but only 53 % at the end of the 10-day window. In a previous test run the 10-day window criteria was met. This test was invalid because the inoculum blank had a lower BOD than normally observed. However, the study has to be scored as Klimisch 3, as this approach by a manometric respiration test is not suitable for the physical and chemical properties of the test item n-Hexyl methacrylate (low solubility and volatile). In the study report, it is mentioned that it can not be excluded that a portion of the test item evaporated from the test solution. Also the CO2 evolution study was not suitable for the afore mentioned properties. Thus the results for biodegradation of 28% underestimates the potential biodegradation by far.

In contrast n-Hexyl methacrylate is predicted to be readily biodegradable using Biowin V4.10 calculations. There are no structural alerts or antimicrobial effects that could explain this slower biodegradation compared to the other members of the category which degrade rapidly. Based on a weight of evidence n-Hexyl methacrylate is assumed be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation of n-Hexyl methacrylate reached 66% after 28 days, but only 53 % at the end of the 10-day window. In a previous test run the 10-day window criteria was met. This test was invalid because the inoculum blank had a lower BOD than normally observed. However, the study has to be scored as Klimisch 3, as this approach by a manometric respiration test is not suitable for the physical and chemical properties of the test item n-Hexyl methacrylate(low solubility and volatile). In the study report, it is mentioned that it can not be excluded that a portion of the test item evaporated from the test solution.

Also the CO2 evolution study was not suitable for the afore mentioned properties. Thus the results for biodegradation of 28% underestimates the potential biodegradation by far.

In contrast n-Hexyl methacrylate is predicted to be readily biodegradable using Biowin V4.10 calculations. There are no structural alerts or antimicrobial effects that could explain this slower biodegradation compared to the other members of the category which degrade rapidly. Based on a weight of evidence n-Hexyl methacrylate is assumed be readily biodegradable.