Docosyl 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 based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Justification for type of information:

For "read across justification" please refer to chapter 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (CO2 evolution)

Value:

94

Sampling time:

28 d

Remarks on result:

other: The time taken to pass the window between 10 % and 60 % biodegradation was approximately 8 days - therefore the ready biodegradability criterion (10-day-window) was satisfied in this test.

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Justification for type of information:

For "read across justification" please refer to chapter 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

ca. 79

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

ca. 11.1

Sampling time:

2 d

Parameter:

% degradation (O2 consumption)

Value:

ca. 17.6

Sampling time:

3 d

Parameter:

% degradation (O2 consumption)

Value:

ca. 50.2

Sampling time:

10 d

Parameter:

% degradation (O2 consumption)

Value:

ca. 62.4

Sampling time:

15 d

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Justification for type of information:

For "read across justification" please refer to chapter 13.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (CO2 evolution)

Value:

97

Sampling time:

28 d

Remarks on result:

other: the test substance reached 80% degradation at the end of the 10-d window

Interpretation of results:

readily biodegradable

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Justification for type of information:

For "read across justification" please refer to chapter 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

ca. 80

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

ca. 62

Sampling time:

5 d

Parameter:

% degradation (O2 consumption)

Value:

ca. 75

Sampling time:

15 d

Interpretation of results:

readily biodegradable

Reference 5

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

weight of evidence

Justification for type of information:

For "read across justification" please refer to chapter 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

28 d

Remarks on result:

other: Oxygen depletion = 4.325 mg O2/L; ThOD = 5.01 mg O2/L

Interpretation of results:

readily biodegradable

Description of key information

The substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Discussion

No experimental biodegradation data are available for the substance itself. Therefore, the biodegradation potential is assessed based on data available for the close structural analogues 2-Propenoic acid, 2-methyl-, C16-20-alkyl esters (CAS 90551-84-1), 2-Propenoic acid, 2-methyl-, C18-22-alkyl esters (CAS 90551-86-3), octadecyl methacrylate (CAS 32360-05-7) and the primary degradation product methacrylic acid (CAS 79-41-4). In accordance with Annex XI section 1.2 of Regulation (EC) No 1907/2006 (REACH), the information was evaluated in a weight of evidence approach.

In a valid guideline study according to OECD 301 B (Ready Biodegradability: CO2 Evolution Test, modified sturm test) the close structural analogue 2-Propenoic acid, 2-methyl-, C18-22-alkyl esters (CAS 90551-86-3) was exposed to microorganisms, derived from activated sludge of a muncipal sewage treatment plant, under aerobic static conditions (Evonik RohMax GmbH, 2008). The biodegradability of the structural analogue was determined to be 94 % after 28 days based on CO2 evolution. Since 2-Propenoic acid, 2-methyl-, C18-22-alkyl esters reached 84% of degradation at the end of the 10-d window, it passed the 60%-level for ready biodegradability. The positive control sodium benzoate reached 80% biodegradation after 14 days, confirming suitability of inoculum and test conditions. Therefore, the stuctural analogue is regarded as ready biodegradable in the modified sturm test.

The ready biodegradability of the primary degradation product methacrylic acid (CAS 79 -41 -4) was assessed in a 28-d Closed Bottle Test according to OECD Guideline 301 D and in compliance with GLP criteria (MPA, 1(a)/91332, 1992). The initial test concentration of methacrylic acid was 3.0 mg/L. The biodegradation was determined by comparing the oxygen depletion value with the corresponding ThOD. A positive control, a negative control and a sterile control (non-inoculated) was conducted in parallel. The sampling was performed on day 0, 5, 15 and 28. The Oxygen depletion in the inoculated and non-inoculated control series were within the prescribed limits.The substance passed the 10 -day time window criterion (60% degradation within 10 days of attaining the 10% level). Thus, all validity criteria of the test guideline were fulfilled. In conclusion, the primary degradation product methacrylic acid (CAS 79 -41 -4) is considered to be readily biodegradable (86% degradation within 28 days).

The ready biodegradability of the close structural analogue octadecyl methacrylate (CAS 32360-05-7) was asssed in a MITI (I) test according to OECD 301 C (Evonik RohMax GmbH, 1988). After 28 days the biodegradation came to 79%. All validity criteria were fulfilled. In another MITI (I) test with this analogue according to OECD Guideline 301 C (Evonik Oil Additives GmbH, 1995), 75% biodegradation after 15 days was reached. Thus, although the 10 day Window is not readable from the original test data, the criterion for ready biodegradability which requires 60 % biodegradation after 15 days is fulfilled. Therefore, the structural analogue octadecyl methacrylate (CAS 32360 -05 -7) is regarded as readily biodegradable.

The biodegradability of the strucural analogue 2-Propenoic acid, 2-methyl-, C16-20-alkyl esters (CAS 90551-84-1) exposed to microorganisms, which were derived from the activated sludge of a municipal sewage treatment plant, was investigated under aerobic static exposure conditions (Evonik Oil Additives GmbH, UNTER 01-028, 1995). Its biodegradability (based on CO₂ evolution) was calculated to be 97% of the theoretical value (ThC02) after an incubation time of 28 days. Its biodegradation reached 80% at the end of the 10-d window. Significant biodegradation of the test substance was observed after a lag phase of about 4 days. The positive control, sodium benzoate, reached 99% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions. The respective DOC concentrations at the beginning (theoretical values) and at the end of the test (after 28 days) were (in mg/L): 20.0 and 1.03 for the test units, <0.5 and 0.79 for the inoculum blank and 20.1 and 0.93 for the procedure control. The calculated biodegradation based on DOC measurement reached 99% for 2-Propenoic acid, 2-methyl-, C16-20-alkyl esters and 99% for sodium benzoate. The data show that the test compound was almost completely mineralized, since the determined degradation values based on CO₂ evolution were similar to those based on DOC. 2-Propenoic acid, 2-methyl-, C16-20-alkyl esters reached the pass level of 60% for ready biodegradability in the CO₂ Evolution Test within the 10-d window and, therefore, the structural analogue can be regarded as readily biodegradable. All validity criteria of the guideline were fulfilled.

In a valid Closed Bottle Test according to OECD Guideline 301 D, the close structural analogue octadecyl methacrylate (CAS 32360-05-7) was assessed for ready biodegradability (Evonik Oil Additives GmbH, UNTER 01-028, 1995). For the test, predominantly domestic and non-adapted activated sludge from secondary effluent of a sewage plant (Taunusstein, Germany) was used. Its biodegradation was followed by O₂ consumption of the microorganisms. The initial concentration of the structural analogue was  between 1.7 and 7.5 mg/L (based on its COD). A negative control without the structural analogue was run in parallel. The reliability of the method was tested by using a mixture of glucose and glutamine acid as reference material. The test was performed in three sets per treatment. The amount of biodegradable substance was calculated in percent by comparing the BOD-value with the measured COD. In result, degradation reached 62.0 % after 5 days, 75.0 % after 15 days and 80.0% after 28 days. In conclusion, the close structural analogue octadecyl methacrylate (CAS 32360-05-7) was determined to be readily biodegradable in a 10-day-window and after 28 days.

Overall conclusion

Octadecyl methacrylate (Evonik Rohmax GmbH, 1988; Evonik Oil Additives GmbH, 1995), and long-chain alkyl methacrylate esters (C16-C22) (Evonik Rohmax GmbH, 2008; Evonik Oil Additives GmbH, 1995) are demonstrated to be readily biodegradable in biodegadation tests according to OECD 301 C, OECD 301 D and OECD 301 B. 79%, 80% and 97 % biodegradatíon were achieved within 28 days, respectively. Furthermore, the primary degradation product methacrylic acid (CAS 79-41-4) was considered to be readily biodegradable (86% degradation within 28 days), too. Based on the most current and reliable study (Evonik RohMax GmbH, UNTER 08 -047, 2008) with the close structural analogue 2-Propenoic acid, 2-methyl-, C18-22-alkyl esters (CAS 90551-86-3), docosyl methacrylate (CAS 16669-27-5) is considered to be readily biodegradable.