bis(2-ethylhexyl) (4-hydroxy-3,5-dimethoxybenzyl)malonate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006-07-03 to 2006-08-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted 17 July 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

31 July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

471-510-2

EC Name:

-

Cas Number:

872182-46-2

Molecular formula:

C28H46O7

IUPAC Name:

1,3-bis(2-ethylhexyl) 2-[(4-hydroxy-3,5-dimethoxyphenyl)methyl]propanedioate

Test material form:

liquid: viscous

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The inoculum activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage plant Rossdorf, Germany.
The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material per litre were mixed with test water and then aerated until use. The washed activated sludge was aerated overnight and used the following day for the experiment.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

ca. 100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Preparation of Test Flasks:
The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used, but the solutions were dispersed by stirring to achieve a homogeneous solution of the test item.

Incubation:
The closed test flasks were incubated in a climatic chamber under continuous stirring. The consumption of oxygen was determined by measuring the change of pressure in the flasks. Evolved carbon dioxide was absorbed in an aqueous solution (45 %) of potassium hydroxide.

Test Duration: 28 days

Measurement of Oxygen:
The change of pressure in the test flasks was measured by means of a manometric method (BSBBOD-Sensor-System, Aqualytic, 63231 Neu Isenburg, Germany) each day.

Temperature: Temperature was measured each working day in the climatic chamber.

pH Value: pH-values were measured in all flasks at the start and end of the test using a pH-electrode WTW pH 340i.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

26

Sampling time:

28 d

Details on results:

The reference item sodium benzoate was sufficiently degraded to 99 % after 14 days, and to 105 % after 28 days of incubation.
The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum.

In the toxicity control containing both, the test item and the reference item sodium benzoate, 40 % biodegradation was noted within 14 days and 45 % biodegradation was determined after 28 days of incubation.

The oxygen demand in the abiotic control was 0 mg/L.

The test item was degraded to 26 % after 28 days of incubation.

The degradation rate of the test item did not reach 60 % within the 10-day window and after 28 days of incubation. Therefore, the test item is considered not to be readily biodegradable.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

In a Manometric Respirometry Test performed according to OECD 301F and under GLP regulation, the substance was degraded to 26% after 28 days of incubation. The degradation rate of the substance substance did not reach 60% within the 10 -day window and after 28 days of incubation. Therefore, the substance is considered not to be readily biodegradable.

Executive summary:

Purpose

The purpose of this assay was to provide information on the biodegradability of the test item in aqueous environment and thus serve as a rational basis for risk assessment for environmental fate in aqueous compartments.

Study Design

For this purpose, the test item was exposed to activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microorganismsduring exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. This study is recognized by the international test guidelines and should provide a rational basis to assess the ready biodegradation properties of the test item when incubated with activated sludge.

Results

Biodegradation
The test item did not reach 60 % within the 10-day window and after 28 days of incubation the test item was degraded to 26 %.

Biodegradation of sodium benzoate
The reference item sodium benzoate was sufficiently degraded to 99 % after 14 days, and to 105 % after 28 days of incubation (ThOD_NH4).

Biodegradation in the Toxicity Control
In the toxicity control containing both, the test item and the reference item sodium benzoate, 40 % biodegradation was noted within 14 days and 45 % biodegradation was determined after 28 days of incubation.

Oxygen demand of the abiotic control
The oxygen demand in the abiotic control was 0 mg/L.

Conclusion

The degradation rate of the test item did not reach 60 % within the 10-day window and after 28 days of incubation. Therefore, the test item is considered not to be readily biodegradable.