Reaction mass of dodecyl methacrylate and tridecyl methacrylate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar physicochemical, ecotoxicological and toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: methacrylate esters
• the metabolism pathway leads to comparable products (methacrylic acid and medium chain alcohol).

Therefore, read-across from the existing physicochemical, ecotoxicity and toxicity studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see “Justification for read-across” attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see “Justification for read-across” attached to IUCLID section 13

4. DATA MATRIX
see “Justification for read-across” attached to IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Oxygen conditions:

aerobic

Duration of test (contact time):

28 d

Parameter:

% degradation (O2 consumption)

Value:

>= 60

Sampling time:

10 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Reaction mass of dodecyl methacrylate and tridecyl methacrylate is regarded as readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

22 February 2018 to 8 May 2018 (Experimental start to Experimental completion)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source of test material: Kyoeisha Chemical Co., Ltd
- Lot/batch No. of test material: 7061301
- Expiration date of the lot/batch: 13 June 2019
- Purity test date: 13 June 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 20-25 0C (Ambient). In original container as supplied by the Sponsor (tightly closed and away from heat or sunlight)
- Stability under test conditions: Assumed stable for the duration of the test
- Solubility and stability of the test substance in the solvent/vehicle: Low solubility in water (<1.0 mg/L). Stability of the test item in aqueous medium, not performed.
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: None

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: None, test item added as supplied to aqueous medium.

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):

Secondary effluent from the JRF Sewage Treatment Plant treating predominantly domestic sewage was used as the inoculum. The Secondary effluent was filtered through a Whatman No. 1 filter paper. The inoculum was pre-conditioned by aerating at 22 ± 2 °C (in the dark) for 6 days.

The Inoculum was analysed for microorganism concentration and confirmed as 2.29 x 104 CFU/mL.

Duration of test (contact time):

28 d

Initial conc.:

2.31 mg/L

Based on:

test mat.

Remarks:

in mineral medium

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
Preparation of Stock Solution for Mineral Medium: The stock solutions A, B, C and D for mineral medium were prepared in Milli-Q water as described below:
Stock Solutions Chemicals used Quantity (g) Final volume (mL)
A Potassium dihydrogen orthophosphate 0.850 100
Dipotassium hydrogen orthophosphate 2.175
Disodium hydrogen orthophosphate dihydrate 3.340
Ammonium chloride 0.050
B Calcium chloride dihydrate 3.640 100
C Magnesium sulphate heptahydrate 2.250 100
D Iron (III) chloride hexahydrate 0.0250 100
The pH of stock solution A was 7.44.

Preparation of Mineral Medium
Mineral Medium for Stock Solution (mL) Capacity of Conical Flask (L) Diluted With Volume of Diluents (mL)
A B C D

Inoculum Blank (IB) 4 4 4 4 5 Milli-Q water 3984
Test Solution (TS) 4 4 4 4 5 3984
Procedure Control (PC) 4 4 4 4 5 3984
Toxicity Control (TC) 2 2 2 2 2 1992
Test Blank (TB) 4 4 4 5 5 3984
The mineral medium was strongly aerated for 20 minutes and allowed to stand for 20 h at 22 ± 2 C. All operations were performed in a horizontal laminar flow under aseptic condition.

- Additional substrate: None
- Solubilising agent (type and concentration if used): None
- Test temperature: All test bottles were incubated at 22 ± 2 ºC in a BOD incubator.
- pH: The pH of stock solution A was 7.44.
- pH adjusted: no
- Aeration of dilution water: The mineral medium was strongly aerated for 20 minutes and allowed to stand for 20 h at 22 ± 2 C. All operations were performed in a horizontal laminar flow under aseptic condition.
- Suspended solids concentration: The Inoculum was analysed for microorganism concentration and confirmed as 2.29 x 104 CFU/mL.
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 300 mL capasity conical flask
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The mineral medium was strongly aerated for 20 minutes and allowed to stand for 20 h at 22 ± 2 C. All operations were performed in a horizontal laminar flow under aseptic condition.
- Measuring equipment: Dissolved oxygen was measured using DO meter (Model: HQ-40d, Make Supplier: HACH – USA)
- Test performed in closed vessels due to significant volatility of test substance: No
- Test performed in open system: No

SAMPLING
- Sampling frequency: The inoculum blank, test blank, test solution and procedure control were dispensed into their respective pre-labeled BOD bottles (capacity: 300 mL) in duplicate for analysis of DO on day 0, 7, 14, 21, and 28.
The toxicity control was dispensed into its respective pre-labeled bottles in duplicated for day 0, 7, and 14. The day zero samples were analysed for DO immediately after dispensing.
- Sampling method: Dissolved oxygen was measured using a DO meter on day 7, 14, 21, and 28. All test bottles were incubated at 22 ± 2 ºC in a BOD incubator.
- Sample storage before analysis: No

CONTROL AND BLANK SYSTEM
- Inoculum blank: Bulk Solution of Inoculum Blank: The inoculum blank was prepared by mixing 4.0 mL inoculum with 3996 mL of mineral medium in a conical flask of 5 L capacity. The solution was mixed thoroughly. The mean DO value for the toxicity controls were measured on day 0, 7, and 14

Bulk Solution of Procedure Control
The procedure control was prepared by mixing 4.0 mL stock solution of Potassium hydrogen phthalate and 4.0 mL of inoculum to 3992 mL of mineral medium in a conical flask of 5 L capacity. The solution was mixed thoroughly. The final concentration of reference substance in mineral medium was 2.03 mg/L.

- Toxicity control: Bulk Solution of Toxicity Control
The toxicity control was prepared by mixing 2.0 mL stock solution of Potassium hydrogen phthalate, 1.0 mL stock solution of test item and 2.0 mL of inoculum to 1995 mL of mineral medium in a conical flask of 2 L capacity. The solution was mixed thoroughly. The final concentration was 2.03 mg/L of reference substance and 2.31 mg/L of test item in mineral medium. The mean DO value for the toxicity controls were measure on days 0, 7, and 14.

STATISTICAL METHODS: None

Reference substance:

other: Potassium hydrogen phthalate

Key result

Parameter:

% degradation (DOC removal)

Remarks:

Procedure control

Value:

82.55

Sampling time:

28 d

Key result

Parameter:

% degradation (DOC removal)

Remarks:

Test solution

Value:

51.35

Sampling time:

28 d

Details on results:

Treatment % Degradation (Based on ThOD) on day
7 14 21 28
Procedure Control 59.15 74.21 84.26 82.55
Test Solution 36.30 42.13 47.87 51.35
Toxicity Control 41.46 46.38 - -

Results with reference substance:

See below summary table

Treatment	Criteria	Results	Conclusion
Inoculum Blank	Change in DO over 28 day must be ≤ 1.5 mg/L	0.99	Pass
Test Blank		1.18
Procedure Control	Degradation must be > 60% of ThOD within 14 days	74.21	Pass
Test Solution	Residual oxygen over 28 day must be > 0.5 mg/L	3.80	Pass
	Degradable, if oxygen consumption exceeds > 60% of ThOD over 28 day	51.35	Not readily biodegradable
Toxicity Control	Toxic, if % degradation < 25% within 14 days	46.38	Pass – Not toxic

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The percent biodegradation data concluded that C12-13 alkyl methacrylate is not readily biodegradable. The test item showed a maximum degradation of 51.35% on day 28 (i.e. outside guideline pass levels of 70% removal of DOC and 60% of ThOD) of analysis, whereas the reference substance exhibited a normal pattern of degradation (up to 82.55%) within 28 days. The percent degradation by toxicity control was more than 25% after 14 days. Therefore, the test item is regarded as not readily biodegradable and not toxic to microorganisms in the inoculum.

Description of key information

readily biodegradable (Modified MITI Test; based on read-across from structural analogues)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

A study on biodegradation is available for the target substance Reaction mass of dodecyl methacrylate and tridecyl methacrylate. Additional data are available for the source substances Dodecyl methacrylate and Methacrylic acid ester 13.6. A detailed justification for read-across is attached to IUCLID section 13.

 

Based on the results of these studies, Reaction mass of dodecyl methacrylate and tridecyl methacrylate is considered to be readily biodegradable.

 

Hypothesis for the analogue approach

The read-across hypothesis relies on the close structural similarity between the source substances Dodecyl methacrylate and Methacrylic acid ester 13.6 and the target substance Reaction mass of dodecyl methacrylate and tridecyl methacrylate. This read-across hypothesis corresponds to scenario 2 - different compounds have qualitatively similar properties - of the read-across assessment framework i.e. properties of the target substance are predicted to be quantitatively equal to those of the source substance. Namely, the structurally similar source substances Dodecyl methacrylate and Methacrylic acid ester 13.6 predict the environmental fate properties of the target substance Reaction mass of dodecyl methacrylate and tridecyl methacrylate. Toxicological data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

 

Therefore, read-across from the existing biodegradation studies conducted with the source substance is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

A detailed justification for the proposed read-across approach is attached to Iuclid section 13.

 

1. Identity and characterisation of the source substance

 

There is close structural similarity between the source and the target substances and the identity and characterisation of these substances is unambiguous thereby giving a high level of confidence in the validity of the read across.

The target and source substances are manufactured from similar compounds by esterification of methacrylic acid with the corresponding fatty alcohol. Typical trace impurities are water and the corresponding alcohols as well as < 1 % methacrylic acid, which are not of toxicological concern.

The carbon chain length distribution of the resulting mix of long-chain aliphatic methacrylate esters mirrors the chain length distribution of the alcohol(s) used.

 

2. Link of structural similarities and differences with the proposed prediction

Structural similarities:

The target substance Reaction mass of dodecyl methacrylate and tridecyl methacrylate is an ester of Methacrylic acid and mainly linear C12 / C13 alcohols. The source substances Dodecyl methacrylate and Methacrylic acid ester 13.6 are comparable in chain length. Dodecyl methacrylate contains only C12 chains, Methacrylic acid ester 13.6 contains C13 and C15 chains, and thus, odd numbered alkyl chains as the target substance.

 

Structural differences:

There are only minor differences in alkyl chain length between the target and the source substances, which are not relevant for biodegradation.

 

Reliability and adequacy of the source data

All available studies have been conducted according to OECD guidelines and have been assigned a reliability of 1 or 2 as documented in the data matrix (see detailed justification for read-across attached to Iuclid section 13).

 

Overall, the study design of the respective source studies is adequate and reliable for the purpose of this read-across. The results of the study are adequate for classification and labelling and for risk assessment purposes.

 

 

Data availability

In a study according to OECD Guideline 301 D Reaction mass of dodecyl methacrylate and tridecyl methacrylate was not readily biodegradable. The test item showed a maximum degradation of 51.35% on day 28 (i.e. outside guideline pass levels of 70% removal of DOC and 60% of ThOD) of analysis, whereas the reference substance exhibited a normal pattern of degradation (up to 82.55%) within 28 days. The percent degradation by toxicity control was more than 25% after 14 days. Therefore, the test item is regarded as not readily biodegradable and not toxic to microorganisms in the inoculum.

The ready biodegradation of dodecyl methacrylate was investigated in a study conducted according to EEC Directive 84/449/EEC, Degradation – biodegradation, Modified MITI Test, published in official Journal of the European Communities No. L251/199) over a period of 28 days using sludge samples from different places like rivers, lakes, municipal and industrial sewage plants as inoculum. The biodegradation rate was determined by measurement of O2 consumption. Inoculum blank and procedural/functional control with the reference substance aniline was performed.

After 28 days the degradation of Dodecyl methacrylate reached 88.5 %.The functional control reached the pass level 93.8% after 28 d. 60 % degradation was found after 10 days.

Dodecyl methacrylate proved to be readily biodegradable.

 

The ready biodegradation of Methacrylic acid ester 13.6 was investigated in a study conducted according to EEC Directive 84/449/EEC, Degradation – biodegradation, Modified MITI Test, published in official Journal of the European Communities No. L251/199) over a period of 28 days using sludge samples from different places like rivers, lakes, municipal and industrial sewage plants as inoculum. The biodegradation rate was determined by measurement of O2 consumption. Inoculum blank and procedural / functional control with the reference substance aniline were performed.

After 28 days the degradation of Methacrylic acid ester 13.6 reached 76.6 %.The functional control reached the pass level 84.0 % after 28 d.

Methacrylic acid ester 13.6 proved to be readily biodegradable.

In accordance with the Guidance on Information requirements and chemical safety assessment (“Realising that ready biodegradability tests may sometime fail because of the stringent test conditions, positive test results should generally supersede negative test results.”), the results obtained with the source substances dodecyl methacrylate and methacrylic ester 13.6 are assigned a higher weight, and thus, the target substance Reaction mass of dodecyl methacrylate and tridecyl methacrylate is considered to be readily biodegradable.