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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17 Jun 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
GLP compliance:
yes (incl. certificate)
Remarks:
Behörde für Arbeit, Gesundheit und Soziales, Hamburg, Germany
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): public treatment plant, D-24306 Plön
- Storage conditions: The effluent was kept under aerobic conditions in the period between sampling and application
- Preparation of inoculum for exposure: To prepare the inoculum the sample was filtered through a coarse filter, the first 200 mL being discarded. The rest of the filtrate was kept aerobic until use.
- Concentration of sludge: 10E+08 bacteria per L of final volume of the test medium
- Water filtered: yes
- Type and size of filter used, if any: coarse filter
Duration of test (contact time):
28 d
Initial conc.:
2 mg/L
Based on:
test mat.
Details on study design:
TEST CONDITIONS
- Composition of medium: 1 mL of each solutions 1 to 4 was added to 1 L of distilled water.
Solution 1: 0.850 g KH2PO4; 2.850 g K2HPO4 x 3H2O; 3.340 g Na2HPO4 x 2H2O; 0.050 g NH4CL were disolved in distilled water and made uo to 100 mL. The pH was determined as pH 7.56.
Solution 2: 2.25 g MgSO4 x 7H2O were disolved in distilled water and made up to 100 mL.
Solution 3: 3.64 g CaCl2 x 2H2O were disolved in distilled water and made up to 100 mL.
Solution 4: 0.025 g FeCl3 x 6H2O were disolved in distilled water and made up to 100 mL.
- Test temperature: At room temperature (as close as possible at 20 °C)
- Aeration of dilution water: yes; 65 L was aerated strongly for 20 minutes with compressed air.
- Other: All transfer and filling operations of the air saturated water were conducted bubble-free by siphon.

TEST SYSTEM
- Culturing apparatus: BOD bottles
- Number of culture flasks/concentration: 19
- Measuring equipment: Oxygen measuring instrument (OXI DIGI 530 with a Tri Oxmatic-EO 200 oxygen electrode, WTW, D-82362 Weilheim)

SAMPLING
- Sampling frequency: 0, 3, 7, 10, 14, 17, 21, 24, 28 days


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes

Reference substance:
other: sodium acetate
Parameter:
other: dissolved oxygen depletion
Value:
11.1
Sampling time:
28 d
Details on results:
Oxygen depletion in the inoculum control was 0.67 mg O2/L after 28 days, and did not exceed 1.5 mg O2/L over the 28-day exposure period.
Since 33.7% degradation (based on ThOD added as test material and reference compound) was noted in the toxicity control within 14 days of exposure, it can be excluded that VP 50991 was inhibitory to the microorganisms.
Results with reference substance:
The reference compound sodium acetate was biodegraded by an average of 67.5% by exposure day 14 and reached an average biodegradation rate of 66.0% by the end of the 28-day exposure period.
Interpretation of results:
other: not readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Please refer to the attached justification for grouping of substances provided in IUCLID Section 13.
Reason / purpose:
read-across source
Parameter:
other: dissolved oxygen depletion
Value:
11.1
Sampling time:
28 d

Description of key information

key (LPT, 2002a): Dissolved Oxygen Depletion 11.1%  based on  at 2 mg/l test concentration (OECD 301D, GLP), RL1

Key value for chemical safety assessment

Additional information

There are no reliable ready biodegradation data available for N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine (CAS 23410-40-4), therefore good quality data for the analogue, N-[3-(methoxydimethylsilyl)propyl]ethylenediamine (CAS 3069-33-8), have been read across. Both substances share the comparable silanol hydrolysis products, N-[3-(dihydroxymethylsilyl)-2-methylpropyl]ethylenediamine and N-[3-(hydroxydimethylsilyl)propyl]ethylenediamine; the other hydrolysis product being methanol, which is readily biodegradable. Both substances are expected to hydrolyse within the timescale of a ready biodegradation test.

Both N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine and N-[3-(methoxydimethylsilyl)propyl]ethylenediamine within a wider analogue group, than the trimethoxysilane analogue group discussed in Section 1.4. Substances within this wider analogue group, in general, exhibit no evidence of any significant biodegradation once hydrolysis and subsequent biodegradation of alkoxy/acetoxy groups has been taken into account. It is therefore considered valid to read-across the results for N-[3-(methoxydimethylsilyl)propyl]ethylenediamine to fill the data gap for the registered substance.The other hydrolysis product for both substances is methanol, which is readily biodegradable (OECD, 2004a).

This wider analogue group for the ready biodegradability endpoint consists of a number of sub-classes of substances. However, read-across is carried out between substances with the same sub-class in most cases.

Table 4.1.3 presents ready biodegradation data available for substances within the sub-class (III-8) of chlorosilanes, siloxanes, silanes and alkoxysilanes etc, with amino functional group(s) in side chain after any very rapid hydrolysis has been accounted for.Both N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine and N-[3-(methoxydimethylsilyl)propyl]ethylenediamine members of this sub-class.

Additional information is given in a supporting report (PFA, 2013f) attached in Section 13 of the IUCLID dossier. 

The key study of LPT (2002a) was according to OECD 301D and GLP. The biodegradation values calculated from Dissolved Oxygen Depletion performed during the test of 28 days revealed 11.1% at 2 mg/l test concentration. Therefore, the test item was not readily biodegradable under the conditions in the closed bottle test performed. Therefore, the test item was not readily biodegradable under the conditions in the test performed.

Table 4.1.3. Ready biodegradation data available for substances within the relevant sub-class (III-8) of chemicals

CAS

Name

Readily biodegradable? Yes/no

Result: Biodegradation after 28 day

Guideline

Reliability

Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for

027445-54-1

Cyclohexanamine,N-[(diethoxymethylsilyl)methyl]-

No

29% (26% taking into account nitrification)

OECD 301F

1a

-7 (i.e 0)

[N,N-Bis(trimethylsilyl)aminopropyl]methyldiethoxysilane

No

23% (BOD); 22% (TOC)

OECD 301C

1a

-6 (i.e 0)

000919-30-2

3-aminopropyltriethoxysilane

No

67%

Annex V C4-A

1a

0

031024-56-3

N-[3-(trimethoxysilyl)propyl]butylamine

No

24.7%

OECD 301B

1a

-5 (i.e 0)

227085-51-0

N-ethyl-3-trimethoxysilyl-2-methylpropanamine

No

16 - 18%

OECD 301F

1a

-15 (i.e 0)

157923-74-5

2,2-dimethyl-4-(trimethoxysilyl)butylamine

No

36%

OECD 301F

1a

3

003069-33-8

N-[3-(methoxydimethylsilyl)propyl]ethylenediamine

No

11.1%

OECD 301D

1a

-1 (i.e 0)

001760-24-3

N-(3-(trimethoxysilyl)propyl)ethylenediamine

No

39%

Annex V C4-A

1a

2

None

reaction mix (reaction mass of 6 benzylated amine silanes)

No

29 and 17%

OECD 301B

1a

 

149048-48-6

1,3-Benzenedimethanamine, reaction products with 3-chloropropyltrimethoxysilane

No

19% (BOD); 20% (TOC)

OECD 301C

1a

-1 (i.e 0)

082985-35-1

Bis(trimethoxysilylpropyl)amine

No

11-20%

OECD 301D

1a

-30 (i.e 0)