2-Propenoic acid, 2-methyl-, 2-hydroxyethyl ester, phosphate

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:

supporting study

Study period:

2000

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Material consists of approx.70% 2-methacryloyloxyethyl phosphate (CAS#52628-03-2) and approx.30% methyl methacrylate (CAS#80-62-6)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Duration of test (contact time):

48 d

Initial conc.:

112

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Parameter:

% degradation (O2 consumption)

Value:

63

Sampling time:

10 d

Details on results:

Based on the data of the individual O2 determinations, the mean biodegradability in the Manometric Respirometry Test of the testing material was calculated to be 80% after 28 days.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The testing material is biodegradable.

Executive summary:

Based on the data of the individual O2 determinations, the mean biodegradability in the Manometric Respirometry Test of the testing material was calculated to be 80% after 28 days.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

The microbial inoculum consisted of activated sludge mixed liquor, collected from the oxidation ditch bioreactor at the Midland Municipal Wastewater Treatment Plant. This facility treats an excess of 11 million liters of wastewater per day, of which > 90% is from domestic sources. The activated sludge was collected one day prior to initiation of the test, and was continuously aerated until used. Prior to use, the activated sludge was screened through 500-µm nylon mesh, and briefly homogenized. The mixed liquor suspended solids (MLSS) content of the homogenized sludge was determined gravimetrically to be 1,563 mg/L. Based on this determination, 315 mL of the homogenized activated sludge was added to 16 liters of the filtered mineral medium to yield a final MLSS concentration of approximately 30 mg/L.

Duration of test (contact time):

28

Initial conc.:

54.6 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The biodegradation reaction mixtures were prepared in specially designed 1-liter glass reaction vessels, each containing a 500-mL portion of the inoculated mineral medium. The reaction vessels are designed with flat glass bottoms to accommodate stirring with large PTFE-coated magnetic stir bars. These vessels are also fitted with 20 x 105 mm glass side baffles to facilitate complete mixing/aeration of the stirred reaction mixtures. All reaction vessels were labeled using a color coded system for vessel identification. Inoculum Blanks, containing the inoculated mineral medium and without added test or reference material, were prepared in duplicate. These Inoculum Blanks were used to determine mean values for cumulative O2 consumption, CO2 evolution, and dissolved organic carbon (DOC) concentration in the absence of added test material. Biodegradation of a reference material, aniline, was determined in duplicate Positive Control mixtures to verify the viability of the inoculum. Biodegradation of the test material in the Test Suspensions was determined by adding test material directly to the inoculated mineral medium (500 mL). A single Toxicity Control reaction mixture was similarly prepared by combining the test material and aniline in the inoculated mineral medium. The rate and extent of aniline degradation in the Toxicity Control reaction mixture was used to assess whether the test material was inhibitory to the microbial inoculum. A single Abiotic Control mixture was prepared by adding mercuric chloride (sterilizing agent, 248 mg/L) to inoculated mineral medium containing the test material. This Abiotic Control was used to determine the amount of O2 consumption, CO2 evolution, and DOC removal measured in the Test Suspensions which is attributed to abiotic reactions.
After addition of test material, aniline, and sterilizing agent to the appropriate vessels, the pH of the reaction mixtures were measured and adjusted as necessary to 7.4 ± 0.2, then stirred for 30 minutes to homogenize their contents prior to initiation of the test. Samples (30 mL) of the Inoculum Blank, Positive Control, and Toxicity Control reaction mixtures were collected for initial analyses of DOC and nitrate/nitrite analysis. Prior to measurement of initial oxygen and CO2 concentrations, the headspace volume of each individual reaction vessel was determined by the automated respirometer system. Other specific operating parameters for the respirometer system are described in detail in the study file. A temperature reference vessel containing 500 mL water was incubated and stirred alongside the biodegradation reaction mixtures in this test. The water temperature in this vessel was recorded by a submerged NIST-traceable thermocouple. The biodegradation reaction mixtures were incubated in the dark at a temperature between 20 and 24 C, and maintained within ± 1 °C of the average incubation temperature. The reaction mixtures were continuously stirred by a PTFE-coated magnetic stir bar rotating at a setting of 150 rpm.

Reference substance:

aniline

Test performance:

The inoculum used in this test produced > 60% biodegradation of the reference material, aniline, within the required 10-day window prior to day 14 of the test. The 60% DO2 pass level was exceeded after 11.9 days, and biodegradation based on O2 consumption, CO2 production and DOC removal reached 113 ± 0%, 86 ± 0.5% and 99.2 ± 0.0%, respectively, at the end of the test. For the Positive Controls and Test Suspensions, the extent of biodegradation recorded for replicate reaction mixtures must not differ by more than 20% DO2 at the end of the 10-day window, plateau of degradation, or the end of the test (OECD, 1992). In this test, the percentage of test substance biodegradation in the replicate Test Suspensions differed by 6.96% DO2 over the duration of the study. The difference in percentage of aniline biodegradation in replicate Positive Controls at the plateau of degradation was 1.99% The Toxicity Control mixtures containing aniline (241 mg/L as ThOD) and test material (53.4 mg/L as ThOD) showed no evidence for inhibition of the microbial inoculum by the test material. The pH of the Test Suspensions decreased by no more than 0.06 pH units from their initial values over 28 days, and showed only a 0.11 pH unit (maximum) difference relative to the Inoculum Blanks at the end of the test.

Key result

Parameter:

% degradation (O2 consumption)

Value:

93.1

Sampling time:

28 d

Parameter:

% degradation (CO2 evolution)

Value:

78.3

Sampling time:

28 d

Parameter:

% degradation (DOC removal)

Value:

91.8

Sampling time:

28 d

Details on results:

Biological oxygen demand: Biological oxygen demand (BOD) is used as the primary indicator of biodegradation in the OECD 301F: Manometric Respirometry test. These measurements of BOD showed the extent of biodegradation of the test material under the conditions of this test. The time required for biodegradation to exceed 10% DO2 (i.e., the lag period) was 1.6 days and the 60% DO2 level was exceeded after 11.9 days. By the end of the 28-day test, biodegradation of the test material reached 93.1% DO2.

CO2 evolution: Two of the OECD tests for ready biodegradability utilize measurements of CO2 evolution to indicate the extent of test material mineralization. The pass criterion for these tests is 60% of theoretical carbon dioxide evolution. While measurement of CO2 evolution is not a requirement of OECD Guideline No. 301F, these supplemenal measurements of CO2 evolution confirmed the extent of test material biodegradation derived from oxygen consumption. Biodegradation of the test material exceeded 10% DCO2 after 3.1 days, and after 28 days reached 78.3% DCO2. These results are consistent with those obtained through BOD analysis.

DOC analysis: DOC analyses also indicated that biodegradation of the test material occurred under the conditions of this test. The initial DOC concentration (mean ± 1 SD) in the Test
Suspensions was 17.5 ± 0.4 mg/L, which indicated that the test substance was completely dissolved in the inoculated mineral medium. The DOC concentration after 28 days was 1.43 ± 1.5 mg/L, which equates to a 91.8% reduction of the initial DOC concentration.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Biodegradation of the test material in the Test Suspension indicated a total of 93.1% biodegradation over the 28-day test period (as determined by BOD). The results exceeded the threshold value of 60% biodegradation right at the 10-day window.
Therefore, the reaction product of 2-hydroxyethyl methacrylate (HEMA) and polyphosphoric acid (PPA) which contains multiple components, can be classified as “readily biodegradable” based upon results from this test (OECD, 1992). Validity criteria specified by the OECD for viability of the inoculum, pH, and control of temperature were met in this study.

Executive summary:

The ready biodegradability of the reaction product of 2-hydroxyethyl methacrylate (HEMA) and polyphoshoric acid (PPA) was determined using the OECD Guideline No. 301F: Manometric Respirometry Test. Biodegradation of the reaction product of 2-hydroxyethyl methacrylate (HEMA) and polyphoshoric acid (PPA) (55.7 mg/L equivalent to 54.6 mg/L as theoretical oxygen demand [ThOD]) reached 93.1% based on biological oxygen demand (BOD) at the end of this 28-day test.

Biodegradation of the test material started at approximately 1.6 days after the addition of the test material into the reaction mixture and exceeded 60% within 11.9 days of the initiation of the test, which indicates that the 10-day window criteria described in the OECD 301F guideline was met.

Therefore, the reaction product of 2-hydroxyethyl methacrylate (HEMA) and polyphoshoric acid (PPA) can be classified as “readily biodegradable.”

The results of this test met or exceeded OECD-specified criteria for viability of the inoculum, pH, and control of temperature. Biodegradation of a reference material (aniline, 100 mg/L equivalent to 241 mg/L as ThOD) exceeded 60% by 7.4 days, verifying the viability of the activated sludge inoculum. A Toxicity Control mixture, containing both aniline (100 mg/L equivalent to 241 mg/L as ThOD) and the test material (53.4 mg/L equivalent to 52.5 mg/L as ThOD), showed no evidence for inhibition of the microbial inoculum by the test material.

Oxygen consumption and CO2 evolution observed in the reaction mixtures could be attributed solely to biological activity, as no net O2 consumption or CO2 production was measured in an Abiotic Control mixture containing the test material and a chemical sterilant (HgCl2, 248 mg/L).

Description of key information

The ready biodegradability of the reaction product of 2-hydroxyethyl methacrylate (HEMA) and polyphoshoric acid (PPA) was determined using the OECD Guideline No. 301F: Manometric Respirometry Test. 

 

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The ready biodegradability of the reaction product of 2-hydroxyethyl methacrylate (HEMA) and

polyphoshoric acid (PPA) was determined using the OECD Guideline No. 301F: Manometric

Respirometry Test. Biodegradation of the reaction product of 2-hydroxyethyl methacrylate (HEMA)

and polyphoshoric acid (PPA) (55.7 mg/L equivalent to 54.6 mg/L as theoretical oxygen demand

[ThOD]) reached 93.1% based on biological oxygen demand (BOD) at the end of this 28-day test.

Biodegradation of the test material started at approximately 1.6 days after the addition of the test

material into the reaction mixture and exceeded 60% within 11.9 days of the initiation of the test,

which indicates that the 10-day window criteria described in the OECD 301F guideline was met.

Therefore, the reaction product of 2-hydroxyethyl methacrylate (HEMA) and polyphoshoric acid

(PPA) can be classified as “readily biodegradable.”

The results of this test met or exceeded OECD-specified criteria for viability of the inoculum,

pH, and control of temperature. Biodegradation of a reference material (aniline, 100 mg/L

equivalent to 241 mg/L as ThOD) exceeded 60% by 7.4 days, verifying the viability of the

activated sludge inoculum. A Toxicity Control mixture, containing both aniline (100 mg/L

equivalent to 241 mg/L as ThOD) and the test material (53.4 mg/L equivalent to 52.5 mg/L as

ThOD), showed no evidence for inhibition of the microbial inoculum by the test material.

Oxygen consumption and CO2 evolution observed in the reaction mixtures could be attributed

solely to biological activity, as no net O2 consumption or CO2 production was measured in an

Abiotic Control mixture containing the test material and a chemical sterilant (HgCl2, 248 mg/L).