Reaction mass of [3-(trimethoxysilyl) propyl]urea, [3-(dimethoxyethoxysilyl) propyl]urea, [3-(methoxydiethoxysilyl) propyl]urea and [3-(triethoxysilyl) propyl]urea.

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:

key study

Study period:

28 Aug - 23 Oct 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Qualifier:

according to guideline

Guideline:

other: "Method for Testing the Biodegradability of Chemical Substances by Microorganisms" stipulated in the "Testing Methods for New Chemical Substances" (MITI, Japan, 1974)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: On-site sludge sampling was carried out at the following 10 locations in Japan; sampling date was in June 2003; city sewage was sampled in return sludge from sewage plants and from lakes, rivers and sea surface water and soil was collected if was in contact with atmosphere
Fushikogawa city sewage plant (Sapporo-shi, Hokkaido)
Fukashiba industrial sewage plant (Kashima-gun, Ibaraki)
Nakahama city sewage plant (Osaka-shi, Osaka)
Ochiai city sewage plant (Shinjuku-ku, Tokyo)
Kitakami River (Ishinomaki-shi, Miyagi)
Shinano River (Niigata-shi, Niigata)
Yoshino River (Tokushima-shi, Tokushima)
Lake Biwa (Otsu-shi, Shiga)
Hiroshima Bay (Hiroshima-shi, Hiroshima)
Dookai Bay (Kitakyushu-shi, Fukuoka)
- Preparation of inoculum: Activated sludge was prepared as follows to maintain its uniformity. The filtrate (5L) of the supernatant of the activated sludge (the activated sludge cultivated the mixed filtrate (10L) of the supernatant of sludge collected at the ten locations) cultivated about 3 months was mixed with mixed with the filtrate (5L) of the supernatant of a ludge collected newly at each location. The mixed filtrate (10L) was aerated (prefiltered open air was used) after the pH value of the mixture was adjusted to 7.0±1.0.
- Concentration of sludge: 4100 mg/L
- Method of cultivation: Roughly 30 minutes after ceasing aeration of the sludge mixture, supernatant corresponding to about 1/3 of the whole volume was removed. Dichlorinated water was added to the remaining portion so that the total volume reached 10L. This mixture was aerated, and then a predetermined amount of synthetic sewage was 0.1 wt% in the volume of dichlorinated water added. This procedure was repeated once every day. Cultivation was carried out at 25±2 °C.
- composition of synthetic sewage: glucose, peptone and potassium dihydrophosphate were dissolved in purified water to obtain 50 g/L of the solution for each component. The pH of the solution was adjusted to 7.0±1.0 with sodium hydroxide.
- Control and use of sludge: During cultivation, the appearance of the supernatant, sedimentation of the sludge formation of flock, pH, dissolved oxygen concentration in the solution and temperature were checked to maintain anormal state of sludge. It was confirmed that these were within the scope of the control standard stipulated in the "Testing Methods for New Chemical Substances", and these results werestored as raw data. Microflora in the activated sludge was microscopically observed and the sludge with the no abnormal symptomswas used for the test.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Details on study design:

TEST CONDITIONS
- Composition of medium: Each 3 mL of solutions A, B, C and D, which are prescribed in JIS K 0102-1998 section 21, was made up to 1000 mL with purified water (Takasugi Seiyaku Co., Ltd.), and then the pH of this solution was adjusted to 7.0.
- Test temperature: 25 ± 1 °C
- pH: 7.0
- pH adjusted: yes
- Suspended solids concentration: 30 mg/L


TEST SYSTEM
- Culturing apparatus: Closed system oxygen consumption measuring apparatus
- Number of culture flasks/concentration: 3
- Measuring equipment: BOD (autorecording using a data sampler); TOC (Total organic carbon analyzer)
- Test performed in open system: no

SAMPLING
- Sampling frequency: periodically

CONTROL AND BLANK SYSTEM
- Abiotic control: yes
- positive control: yes
- Other: control blank

Reference substance:

aniline

Parameter:

other: BOD

Value:

40

Sampling time:

28 d

Parameter:

% degradation (TOC removal)

Value:

43

Sampling time:

28 d

Results with reference substance:

Percentage biodegradations of aniline calculated by the BOD values were 64% and 76% after 7 and 14 days, respectively.

Table 1: Analytic results of test solution
		Water + test item	Sludge + test item			Theoretical amount
		Vessel 6	Vessel 1	Vessel 2	Vessel 3
BOD^*	mg	0.1	21.3	22.8	22.3	56.1
Residual amount and percentage residue^*of DOC	mgC	12.4	7.1	6.9	7.1	12.0
	%	103	59	58	59	-
Produced amount and percentage production of ethanol (GC)	mg	8.1	0	0	0	9.2
	%	88	0	0	0	-
Produced amount and percentage prdocution of ethanol (GC)	mg	4.5	0	0	0	4.3
	%	104	0	0	0	-
Produced amount and percentage production of water-soluble silicon (AA)	mg	3.5	3.5	3.3	3.3	3.6
	%	97	96	90	92	-
^*The value of control blank was subtracted from the value of the test solutions (sludge + test item)

Table 2: Percentage biodegradation
Method	Percentage biodegradation (%)
	Vessel 1	Vessel 2	Vessel 3	Average
BOD	38	41	40	40
TOC	43	44	43	43

Interpretation of results:

other: not readily biodegradable

Conclusions:

It was concluded that this test conditions were valid.
Under the present conditions, the test item was hydrolyzed and methanol, ethanol and water-soluble converted products containing silicon were produced. Methanol and ethanol were biodegraded by microorganisms. Water-soluble converted products containing silicon remained in the test solution.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP- Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: municipal sewage treatment plant

Details on inoculum:

- Source of inoculum/activated sludge: The source of test organisms was secondary effluent freshly obtained from a municipal sewage treatment plant "Waterschap de Maaskant", 's Hertogenbosch, the Netherlands
- Treatment: Secondary effluent was filtered through a coarse filter paper, the first 200 mL was discarded. The filtrate was kept aerated until inoculation.
- Water filtered: yes

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Initial conc.:

5 mg/L

Based on:

test mat.

Details on study design:

TEST CONDITIONS
- Composition of medium: For the preparation of the test media a stock solution of 100 mg/L was prepared in mineral medium. Thorough mixing (15 min) was used to accelerate dissolving and to ensure homogeneity. Amounts of the stock solution corresponding to the test concentrations were added to the test medium.
- Components of stock solution: a)KH2PO4 8.50 g; K2HPO4 21.75g; Na2HPO4 12H2O 67.20; NH4Cl 0.50 g; dissolved in 1 L Milli-Q water, pH ± 0.2; b) MgSO4 7H2O 22.5; dissolved in 1 L Milli-Q water; c) CaCl 2H2O 36.40 g; dissolved in 1 L Milli-Q water ; d) FeCl36H2O 0.25; dissolved in 1 L mIlli-Q water; 1mL of solution a) and d) was mixed and made up to 1 L with Milli-Q water
- Test temperature: The temperature recorded daily in a vessel with water in the same room varied between 20 and 22°C.
- pH: pH at the start 7.5 to 7.6
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2 flasks per concentration
- Measuring equipment: Oxygen Meter (WTW OXI 530 dissolved oxygen meter, TriOxmatic EO 200 oxygen electrode, electrolyte type ELY/N)
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no


SAMPLING
- Sampling frequency: Immediately at the start of the experiment (day 0) and at day 7, 14, 21 and 28 in duplicate.


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Other: positive control

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

31

Sampling time:

28 d

Remarks on result:

other: For test concentration of 2 mg/L

Parameter:

% degradation (O2 consumption)

Value:

24

Sampling time:

28 d

Remarks on result:

other: For test concentration of 5 mg/L

Details on results:

ThOD was calculated to be 1.81 mg/O2 per mg for A-1160. The criterion for readily biodegradability (at least 60% degradation within 10 days of biodegradation exceeding 10%) was not met. Since all criteria for acceptibility of the test were met, this study was considered to be valid.

Results with reference substance:

The oxygen depletion in the toxicity control was always more than 75% of the sum of the oxygen depletion of the positive control and the test substance (2 mg/L). Therefore A-1160 (methanol stripped) was assumed to be not inhibitory.

Table 1: Oxygen depletion at different points in time.
Test medium	Concentration (mg/L)	Oxygen depletion (mg BOD/L) after x days
		7	14	21	28
Positive control	2	1.11	1.16	1.39	1.54
Test substance   (2 mg/L)	2	0.67	1.00	1.02	1.14
Test substance   (5 mg/L)	5	2.00	2.38	2.31	2.20
Toxicity control	^*	1.75	2.12	2.06	2.23
^*Toxicity control contains positive control and test substance low

Table 2: % Biodegradation at different points in time.
Test medium	Concentration (mg/L)	Oxygen depletion (mg BOD/L) after x days
		7	14	21	28
Positive control^*	2	71	76	89	99
Test substance   (2 mg/L)^**	2	19	28	28	31
Test substance   (5 mg/L)^**	5	22	26	26	24
^*ThOD positive control, sodium acetate: 0.78 mg O2/mg ^**ThOD test substance, A-1160 (methanol stripped): 1.81 mg O2/mg

Interpretation of results:

other: not readily biodegradable

Conclusions:

Although significant biodegradation of A-1160 (methanol stripped) was recorded during the test period (maximally 31%). A-1160 (methanol stripped) was not readily biodegradable under conditions in the closed bottle test presently performed.

Description of key information

key (Matsunobu, 2003): Degradation 40%  based on BOD and 43% based on TOC removal at 100 mg/l test concentration (OECD 301C, GLP), RL1
supporting (Desmares.Koopmans, 1999): 31% and 26% Degradation at test concentrations of 2 and 5 mg/l (OECD 301D, GLP), RL1

Additional information

For ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (116912-64-2) two studies are available. The key study of Kurume Laboratory (2003) was according to OECD 301D and GLP. The biodegradation values calculated from BOD and TOC removal performed during the test of 28 days revealed 40 and 43% at 100 mg/l test concentration, respectively. Therefore, the test item was not readily biodegradable under the conditions in the closed bottle test performed.

The supporting study of NOTOX (1999a) was according to OECD 301D and GLP. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed 31 and 26% degradation of ureidopropyltrialkoxysilane, mixed methoxy and ethoxy esters (116912-64-2) at the lowest (2 mg/l) and the highest (5 mg/l) concentration, respectively.

It is not expected that the silanol hydrolysis products show any significant degradation. The other hydrolysis products are ethanol and methanol respectively. Ethanol and methanol are readily biodegradable and are well characterised

Therefore, the test item was not readily biodegradable under the conditions in the closed bottle test performed.