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Environmental fate & pathways

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:
16 Jul - 26 Sep 2002
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: activated sludge taken from a WTP (Groß-Zimmern, Germany) treating domestic sewage
- Preparation of inoculum for exposure: the sludge was washed
- Initial cell/biomass concentration: 30 mg/L
Duration of test (contact time):
28 d
Initial conc.:
25.1 - 25.5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: reconstituted deionised water
- Test temperature: 21 - 22 °C
- pH: 7.6 - 7.9
- pH adjusted:no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: Manometric test system
- Number of culture flasks/concentration: 2
- Measuring equipment: BSB/BOD-Sensor system
- Details of trap for CO2 and volatile organics if used: potassium hydroxide (45% aquaeous solution)


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 1 replicate
- Abiotic sterile control: yes, 1 replicate
- Toxicity control: yes, 1 replicate
Reference substance:
aniline
Remarks:
Batch No.: K28124761
Parameter:
% degradation (O2 consumption)
Value:
30 - 34
Sampling time:
28 d
Details on results:
Degradation in toxicity control: 70% after 14 days and 68% after 28 days of incubation
Results with reference substance:
Degradation of Anilin: 82% after 14 days and 94% after 28 days of incubation.
Validity criteria fulfilled:
yes
Interpretation of results:
other: not readily biodegradable
Conclusions:
The substance was found not to be readily biodegradable (30-34%, O2 consumption) within 28 d according to OECD criteria.
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:
% degradation (O2 consumption)
Value:
30 - 34
Sampling time:
28 d

Description of key information

Biodegradation in water, screening tests: 30-34 % in 28 days (OECD 301F)

Key value for chemical safety assessment

Additional information

There are no reliable ready biodegradation data available for (chloromethyl)triethoxysilane (CAS No. 15267-95-5), therefore good quality data for the structurally-related substance, Silane, (chloromethyl)dimethoxymethyl- (CAS No. 2212-11-5), have been read across. Both substances hydrolyse to structurally-related silanol hydrolysis products, (chloromethyl)silanetriol and (chloromethyl)methylsilanediol, the other hydrolysis products being methanol and ethanol, respectively, which are readily biodegradable (OECD, 2004a and b).

Both chloromethyl)triethoxysilane (CAS No. 15267-95-5) and silane, (chloromethyl)dimethoxymethyl- (CAS No. 2212-11-5) are within a wider analogue group, than the 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.

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.

Table4.1.4presents ready biodegradation data within the analogue group (III-15) of chlorosilanes, siloxanes, silanes and alkoxysilanes etc, with chloroalkyl functional group(s) in side chain after any very rapid hydrolysis has been accounted for.

 Both chloromethyl)triethoxysilane (CAS No. 15267-95-5) and silane,(chloromethyl)dimethoxymethyl- (CAS No. 2212-11-5) are members of this sub-class.

It is therefore considered valid to read-across the results for silane,(chloromethyl)dimethoxymethyl- to fill the data gap for the registered substance. Additional information is given in a supporting report (PFA, 2013f) attached in Section 13 of the IUCLID dossier.

Table 4.1.4: Ready biodegradation data available for substances within the relevant sub-class (III-15) of chemicals.

CAS

Name

Readily biodegradable? Yes/no

Result: Biodegradation after 28 day

Guideline

Reliability

Corrected % biodegradation once alkoxy/acetoxy biodegradation is accounted for

002212-11-5

Silane, (chloromethyl)dimethoxymethyl-

No

30-34%

OECD 301F

1a

-16

007787-93-1

Dichloro(3-chloropropyl)methylsilane

No

0%

EC C4-C

1a

0

013501-76-3

(3-chloropropyl)diethoxymethylsilane

No

56%

EC C4-A

1a

6

002530-87-2

3-chloropropyltrimethoxysilane

No

43%

OECD 301 B

1

-7

005089-70-3

(3-chloropropyl)triethoxysilane

No

46%

EC C4-C

1a

-21

002344-80-1

Chloromethyltrimethylsilane

No

6%

OECD 301D

1a

6

In the study 30–34 % biodegradation was observed in 28 days. The study was conducted according to OECD guideline 301F and is considered reliable (IBACON, 2002). This is selected as the key study.