2-isocyanatoethyl methacrylate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen, Düsseldorf, Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany
- Preparation of inoculum for exposure: The sludge was washed in mineral medium and centrifuged (at 1100 g for 10 minutes). The supernatant was discarded. The concentrated sludge was suspended in mineral medium to a concentration of 1 - 3 g suspended solids/L. The sludge was aerated with CO2-free air over night to purge the system of carbon dioxide. A sample was withdrawn just before use for the determination of the dry weight of the suspended solids.
- Concentration of sludge: The concentration used in the test was 29 mg dry mass/litre (87 mg dry mass/3 L).

Duration of test (contact time):

28 d

Initial conc.:

ca. 20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: For the preparation of the stock solutions for mineral medium the followiing reagents (anaytical grade) were used:
(a) KH2PO4: 8.50 g/L; K2HPO4: 21.75 g/L; Na2HPO4 x 2H2O: 33.40 g/L; NH4Cl: 0.50 g/L.
(b) CaCl2 x 2H2O: 36.40 g/L
(c) MgSO4 x 7H2O: 22.50 g/L
(d) FeCl3 x 6H2O: 0.25 g/L
The mineral medium applied in the test contained 10 mL/L and 1 mL/L of the mineral stock solution a and b-d, respectively.
- Test temperature: 22 °C ± 2 °C
- pH: 7.4
- pH adjusted: yes
- CEC (meq/100 g):
- Aeration of dilution water: Throughout the test, the vessels were aerated by the passage of carbon dioxide free air at a controlled rate during the incubation period.
- Suspended solids concentration: 29 mg/L
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 5-litre flasks containing 2400 mL mineral medium
- Number of culture flasks/concentration: 2 vessels containing test item and inoculum
- Measuring equipment: The samples of suspensions (DOC measurement) were filtered through ROTH PET filters (0.45 µm) as soon as they are taken. The samples of the hydroxide absorbers were measured without any manipulation to avoid CO2 enrichment.
The measurements of DOC and TIC concentration were carried out using a TC analyser (Shimadzu TOC-V-CPH). Analysis was done directly after sampling).


SAMPLING
- Sampling frequency: Days of sampling for CO2 measurement were day 0, 1, 3, 7, 10, 14, 17, 21, 28 and 29.
- Sampling method: The process of biodegradation was followed by CO2 trapped in sodium hydroxide and measured as inorganic carbon. On the days of CO2 measurement, the sodium hydroxide absorbers were disconnected and aliquots of the solutions were measured regarding the TIC concentration. New absorbers (each containg 200 mL fresh 0.05 M sodium hydroxide) were connected to the test vessel.
On the 28th day 1 mL of concentrated hydrochloric acid was added to each test vessel. Subsequently, they were aerated overnight to drive off the carbon dioxide present in the test suspension. On day 29 the last analysis of evolved carbon dioxide was done. Additionally, the biodegradation was measured by determining the DOC in samples of suspension taken at start and 28 d after addition of the test item. The samples at day 28 were taken before the concentrated hydrochloric acid was added.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 vessels containing only inoculum
- Abiotic sterile control: 1 vessel containing test item and a sterilising agent
- Toxicity control: 1 vessel containg test item, reference item and inoculum

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

87

Sampling time:

28 d

Details on results:

The biodegradation of MOI in the static test was found to be 87% on the basis of the values obtained by measurement of the trap solutions and 100% on the basis of the DOC values obtained after 28 days. Biodegradation within the 10-day-window was found to be 68% on the basis of the values obtained by measurement of the trap solutions.

Results with reference substance:

The degradation of the reference substance sodium benzoate had reached 95% within the first 14 days (based on IC in trap solutions).

No inhibitory effects of the test substance were observed in the toxicity control (more than 25% degradation occurred within 14 days) in the toxicity control. Biodegradation was 80% after 14 days.

Interpretation of results:

readily biodegradable

Description of key information

Biodegradation in water: readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Readily biodegradability of 2 -isocyanatoethyl-methacrylate (MOI) was investigated in a study by Simon (2012). This test was performed according to OECD Guideline 301B and EU Method C.4 -C in accordance with GLP requirements. The test substance was incubated in activated sludge at a concentration of approximately 20 mg/L DOC at 22 ± 2 °C. At the end of the test, after 28 days, the biodegradation of MOI was 87% and the 10 -days window was reached (biodegradation was 68% after 10 days). The test substance was thus considered as ready biodegradable under test conditions.

The results from the toxicity control containing test and reference substance (80% biodegradation within 14 days) indicate that MOI has no inhibitory effect on the activity of the sludge microorganisms.