Carbonic acid, ethyl methyl ester

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: screening tests

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 17- July 7, 1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was performed in compliance with the Good Laboratory Practice (GLP) regulations (May 12,1981). The test was conducted according to the "Method for Testing the Biodegradability of Chemical Substances by microorganisms" stipulated in the "Testing Methods for New Chemical Substances" (July 13, 1974, Kanpogyo No.5, Planning and Coordination Bureau, Environment Agency, Yakuhatu No.615, Pharmaceutical Affairs Bureau, Ministry of health and Welfare, and 49 Kikyoku No.392, Basic Industries Bureau, Ministry of International Trade and Industry, Japan). The test method is very similar to one stipulated in the OECD Guideline for Testing of Chemicals "Ready Biodegradability : 301C, Modified MITI Test (I)" (Revised July 17, 1992).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Principles of method if other than guideline:

None

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

433-480-9

EC Name:

-

Cas Number:

623-53-0

Molecular formula:

C4H8O3

IUPAC Name:

ethyl methyl carbonate

Details on test material:

Name: Ethyl methyl carbonate
Purity 99.8 %

Appearance Transparent liquid
Solubility in water 40 g/L

Study design

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):
Fukogawa city sewage plant (Sapporo-shi Hokkaido)
Fukashiba industry sewage plant (Kashima-gun Ibaragi)
Nakahama city sewage plant (Osaka-shi Osaka)
Ochiai city sewage plant (Shinjuku-ku Tokyo)
Kitakami river (Ishinomaki-shi Miyagi)
Shinano river (Nishikanbara-gun Niigata)
Yoshino river (Tokushima-shi Tokushima)
Lake Biwa (Otsu-shi Shiga)
Hiroshima bay (Hiroshima-shi Hiroshima)
Dookai bay (Kitakyushu-shi Fukuoka)

- Date March, 1993
- Method of cultivation:
(1) City sewage
Return sludge from sewage plants was collected.
(2) Rivers, lake and sea
Surface water and surface soil which is in contact with the atmosphere were collected.

- Mixing of fresh and old activated sludge
5 L of the filtrate of the supernatant of an activated sludge, in use at present, was mixed with 500 mL of the filtrate of the supernatant of a newly collected sludge and the mixture was cultured at pH 7.0 ± 1.0 under sufficient aeration using prefiltered open air.

-Culture
About 30 minutes after ceasing the aeration of the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed.
Then an equal volume of dechlorinated water was added to the remaining portion. This
mixture was aerated, and then synthetic sewage was added (to a concentration of 0.1 % (v/v)).
This procedure was repeated once every day. The culturing was carried out at 25±2 °C.

-Synthetic sewage
Glucose, peptone and monopotassium phosphate respectively, were dissolved in dechlorinated water. Each concentration was 5 % (v/v) and the solution was adjusted to pH 7.0± 1.0 with sodium hydroxide.

- Control
During culturing, the appearance of the supernatant, setting of the sludge, formation of flock, pH, dissolved oxygen concentration in the solution and temperature were checked and necessary adjustments were made. Microflora in the activated sludge was microscopically observed and sludge with no abnormal symptoms was used for the test.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

TOC removal

Details on study design:

Preparation of test solutions

(1) Addition of test substance or aniline

(A) (Water + test substance) (n=1, Vessel No.2)

A test vessel containing 297 mL of purified water into which 3 mL of 10 g/L the test substance solution was added. pH of the test solution was measured.

(B) (Sludge + test substance) (n=3, Vessel No.3,4 and 5)

Each test vessel containing 297 mL of basal culture medium into which 3 mL of 10 g/L the test substance solution was added, respectively. pH of the test solution measured.

(C) (Sludge + aniline) (n=1, Vessel No.1)

A test vessel containing 300 mL of basal culture medium into which 29.5 }tL (30.0 mg) of aniline was added.

(D) (Control blank) (n=1, Vessel No.6)

A test vessel containing 300 mL of basal culture medium into which neither the test substance nor aniline was added.

(2) Inoculation with activated sludge

The activated sludge cultured under the conditions described in 12. was added to each test vessel (b), (c) and (d), so that the concentration of suspended solid reached 30 mg/L.

Culturing apparatus and test conditions

(1) Culturing apparatus

Closed system oxygen consumption measuring apparatus
(Coulometer : Ohkura Electric Co., Ltd.)
Data processor
(Data sampler : Asahi Instrument Industries Co., Ltd.)
Vessel 300 mL in volume
Absorbent for carbon dioxide Soda lime No.1 (extra pure reagent, Wako Pure Chemical Industries, Ltd.)
Stirring method Test solution was stirred by a magnetic stirrer.

(2) Test conditions
Temperature 25 ± 1 °C
Duration 28 days
Place Apparatus room No.511 of Kurume Research Laboratories

Reference substance

Reference substance:

aniline

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

98

Sampling time:

28 d

% Degradation 2

Parameter:

% degradation (TOC removal)

Value:

92

Sampling time:

28 d

% Degradation 3

Parameter:

% degradation (test mat. analysis)

Value:

100

Sampling time:

28 d

Details on results:

The degree of biodegradation reached 98 % (O2 consumtion) after 28 days

BOD5 / COD results

Results with reference substance:

40 % degradation after 7 days
74 % degradation after 14 days

Any other information on results incl. tables

(a) Percentage of biodegradtion and BODs obtained for the different vessels as indicated:

Vessel	Day 7		Day 14		Day 21		Day 28
	BOD / [mg]	Deg. / [%]	BOD / [mg]	Deg. / [%]	BOD / [mg]	Deg. / [%]	BOD / [mg]	Deg. / [%]
1	37.7	40	70.7	74	73.2	76	75.3	76
2	0.0	-	0.8	-	1.0	-	2.4	-
3	21.1	49	38.4	84	47.7	104	48.3	101
4	23.3	54	40.2	89	45.2	98	47.3	99
5	19.4	45	35.7	78	41.6	90	44.9	93
6	0.9	-	3.5	-	4.5	-	6.5	-

Vessel 1: Sludge + Aniline
Vessel 2: Water + Test Item
Vessel 3-5: Sludge + Test Item
Vessel 6: blank control

(b) Mean degradation of Vessels 3-5 (sludge + test item)

Day	Mean Degradation [%]
7	49,3
14	83,7
21	97,3
28	97,7

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The degradation of the test item did reach 60 % within the 10 -day window and after 28 days of incubation a degradation of 98 % was observed. Therefore, the test item is considered 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

The test was conducted according to the "Method for Testing the Biodegradability of Chemical Substances by microorganisms" stipulated in the "Testing Methods for New Chemical Substances" (July 13, 1974, Kanpogyo No.5, Planning and Coordination Bureau, Environment Agency, Yakuhatu No.615, Pharmaceutical Affairs Bureau, Ministry of health and Welfare, and 49 Kikyoku No.392, Basic Industries Bureau, Ministry of International Trade and Industry, Japan). The test method is very similar to one stipulated in the OECD Guideline for Testing of Chemicals "Ready Biodegradability : 301C, Modified MITI Test (I)" (Revised July 17, 1992).

Results

All validity criteria were met. The positive control reached the pass level of 40% on day 7 (criterion: </= 7 days) and the pass level of 60 % on day 14 (criterion </= 14 days).

The following data were determined for the test item methyl ethyl carbonate:
10-day-window: day 2 - 12
Degradation at the end of 10-day-window 60 %
Degradation at the end of the test 97.7 %

Conclusion

The degradation of the test item did reach 60 % within the 10 -day window and after 28 days of incubation a degradation of 98 % was observed. Therefore, the test item is considered to be readily biodegradable.