N-{3-[dimethoxy(methyl)silyl]propyl}butan-1-amine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

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 below and the overall justification for grouping of substances attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (CO2 evolution)

Value:

24.7

Sampling time:

28 d

Details on results:

The test substance was degraded to 24.7% after 28 days. Therefore, the test substance is not readily biodegradable.

Interpretation of results:

not readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-10-01 to 2004-12-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the municipal water treatment plant Breisgauer Bucht

- Preparation of inoculum for exposure: washed twice by settling the sludge, decanting supernant and re-suspending the sludge in aerated tap water

- Concentration of sludge: 30 mg per litre

- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

45 other: mg / 1500 ml

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS

- Composition of medium: See below

- Test temperature: 20 - 22*c

- Suspended solids concentration: 30 mg/l activated sludge

- Continuous darkness: no


TEST SYSTEM

- Number of culture flasks/concentration: 3

- Method used to create aerobic conditions: aerated until use

- Measuring equipment: Total carbon analyser TOC-5000A

- Details of trap for CO2 and volatile organics if used: Absorbtion in 0.2 M Sodium Hydroxide

SAMPLING

- Sampling frequency: Day 1, 4, 7, 11, 14, 21 and 28.

- Sampling method: TOC of 0.2 M NaOH trap analysed at intervals stated above.

- Sample storage before analysis: none

CONTROL AND BLANK SYSTEM

- Inoculum blank: no

- Abiotic sterile control: no

- Toxicity control: yes

STATISTICAL METHODS: not needed

Reference substance:

benzoic acid, sodium salt

Test performance:

The biodegradation of the test item was 24.7% within 28 days (after acidification). The test item didn't reach the criterion of a ready biodegradability (60% degradation, 10-d-window).

The reference compound reached the pass levels for ready biodegradability within 4 days.

The degradation in the toxicity control was 59.7 % within 14 days and 72 % within 28 days, so there was no inhibition of the inoculum caused by the test item.

The highest mean CO2-evolution of the blank flasks was 33.8 mg/l within 28 days.

The temperature range was 20 - 22 *c throughout the whole study. The aeration rate was in the tolerated range of 2.7 - 5.5 bubbles/second.

Parameter:

% degradation (CO2 evolution)

Value:

24.7

Sampling time:

28 d

Details on results:

See table 1

The reference compound reached the pass levels for ready biodegradability within 4 days.

Results with reference substance:

See table 1

Table 1.  Percentage biodegradation (% of ThCO₂) of test item, of benzoic acid, sodium salt and of the toxicity control

	Day	0	4	7	11	14	21	28	28*
% Deg	T1	0	14.8	20.2	23.1	21.8	30.4	22.9	21.7
	T2	0	15.3	18.5	21.7	24.1	24	24.7	18.8
	T3	0	13.2	17.5	23.1	28.5	24.2	29.6	33.7
% Deg	R1	0	71.6	82.6	84.5	91.8	101.2	91.1	101.1
	R2	0	66.2	78.1	86.6	96.2	102.4	91.5	105.5
	R3	0	65.1	75.5	78.3	92.7	92.5	93.1	102.4
% Deg	Toxicity control	0	39	46.4	54.3	59.7	67.7	64.5	72.4

T1 – T3 = Dynasylan 1189

R1 – R3 = benzoic acid, sodium salt

* After acidification

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

In a reliable test, the validity criteria of the test guideline were met. After correction of the mean BOD of the Innoculum controls after 28 days, a mean degradation rate of 24.7 % was found. The test item can therefore not be considered ready biodegradable.

Description of key information

N-{3-[dimethoxy(methyl)silyl]propyl}butan-1-amine (CAS No. 120939-52-8) is not readily biodegradable based on read across from N-[3-(trimethoxysilyl)propyl]butylamine (CAS No. 31024-56-3).

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

Data on the biodegradation of N-{3-[dimethoxy(methyl)silyl]propyl}butan-1-amine (CAS 120939-52-8) are not available. In accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 “Grouping of substances and read across” and in accordance with the read across assessment framework (RAAF, ECHA 2017) a read across from N-[3-(trimethoxysilyl)propyl]butylamine (CAS 31024-56-3) was conducted. The substances share very similar silanol hydrolysis products (i.e. [3-(butylamino)propyl](methyl)silanediol and 3-(N-butylamino)propylsilanetriol, respectively). The other hydrolysis products are in both cases methanol. Both substances will hydrolyse within the timescale of a biodegradation test. Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.

The study investigating the biodegradability potential of N-[3-(trimethoxysilyl)propyl]butylamine (CAS 31024-56-3) was conducted according to OECD guideline 301B and GLP. The inoculum (non-adapted activated sludge from a sewage treatment plant) was exposed for 28 d to the test substance and biodegradation was determined based on CO2 evolution measurements. At the end of the experiment, the substance reached a mean biodegradation value of 24.7 % and therefore, does not meet the criterion (60% biodegradation within 28 d) to be considered readily biodegradable.

Based on the results of the analogue substance, the target substance N-{3-[dimethoxy(methyl)silyl]propyl}butan-1-amine (CAS 120939-52-8) is not assumed to be readily biodegradable.