N-[3-(trimethoxysilyl)propylcyclohexylamine]

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 Jul 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Version / remarks:

1988

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Energie, Jugend, Familie und Gesundheit, Wiesbaden, Germany

Analytical monitoring:

no

Details on sampling:

- Concentrations: respiration measured in all concentrations and the control
- Sampling method: For the measurement of the respiration rate a well-mixed sample was poured into a Karlsruher flask after exactly 3 h incubation. The oxygen concentration was measured with an oxygen electrode (ECM-multi, Dr. Lange, Germany), and was recorded for 10 min. Samples were continuously stirred on a magnetic stirrer during measurement. The oxygen consumption (in mg O2 L^-1 min^-1) was determined from the most linear part of the respiration curve.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test substance was directly weighed into the test flasks and flasks were filled each with 284 mL tap water.
- Differential loading: yes

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: sewage plant Gross-Zimmern, Germany
- Preparation of inoculum for exposure: An aliquot of the sludge suspension was weighed, dried and the ratio of wet sludge (g) to its dry weight (g) was determined. On this basis, aliquots of washed sludge suspension, corresponding to 3.1 g dry material per litre, were made up with tap water. To this mixture, 50 mL synthetic sewage feed per litre was added, starting two days prior to use, and the sludge was kept at room temperature under continuous aeration until use.
- Pretreatment: Sludge was washed twice with tap water by centrifugation.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19 - 20 °C

pH:

7.6 - 8.3

Dissolved oxygen:

5.6 - 8.5 mg/L

Nominal and measured concentrations:

0 (control), 10, 32, 100, 320, 1000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 L glass flasks and 250 mL Karlsruher flasks
- Fill volume: 500 mL
- Aeration: with compressed air (approx. 0.6 L/min)
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 2
- Nutrients provided for bacteria: 16 mL/L synthetic sewage feed (16 g peptone, 11 g meat extract, 3 g urea, 0.7 g NaCl, 0.4 g CaCl2x2H2O, 0.2 g MgSO4x7H2O, 2.8 g K2HPO4; filled up to 1 L with deionized water)
- Activated sludge concentration: 200 mL sludge in 500 mL final volume

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED: Oxygen consumption was measured at the end of the 3 h incubation time.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

203 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid: yes
- Relevant effect levels: EC50 (3 h) = 18 mg/L (% inhibition was 14.1, 91.2 and 96.7 at 10, 32, 100 mg/L respectively )

BIOLOGICAL RESULTS:

Table 1: Oxygen consumption and inhibition of activated sludge by the test substance.

Concentration [mg/L]	Oxygen consumption [mg 02/L min]	Inhibition %
control	0.739
1000	0.459	37.9
320	0.764	-3.4
100	0.661	10.5
32	0.804	-8.8
10	0.696	5.9

VALIDITY CRITERIA:

- The respiration rates of the two controls did not differ by more than 15 %.

- The 3-hour EC 50 of the reference substance 3,5- Dichlorophenol was 18 mg/L and thus in the range of 5 to 30 mg/L for the used activated sludge batch.

- The concentration of dissolved oxygen did not drop below 2.5 mg/L during the incubation period, and just before the measurements of the respiration rates the oxygen concentra­tions were at least 6.4 mg/L.

.

Validity criteria fulfilled:

yes

Remarks:

For further details please refer to “Any other information on results incl. tables”.

Conclusions:

No effects caused by the substance to activated sludge were determined in a 3 h exposure study, resulting in an EC50 > 1000 mg/L.

Description of key information

EC50 (3 h) > 1000 mg/L (nominal, OECD 209)

Additional information

The available study (1998) investigates the toxicity of the substance N-[3-(trimethoxysilyl)propylcyclohexylamine] (CAS 3068-78-8) to activated sludge microorganisms and was performed according to OECD 209 and GLP. Activated sludge from a domestic sewage treatment plant was exposed to nominal concentrations of 10, 32, 100, 320 and 1000 mg test item/L for 3 h. Since the substance is expected to hydrolyse rapidly in contact with water, the results from this study refer partly to effects of the hydrolysis products N-[3-(trihydroxysilyl)propylcyclohexylamine] and methanol. After an exposure time of 3 h an inhibition of respiration of 37.9% was recorded in the highest concentration tested, resulting in an EC20 (3 h) = 203 mg/L and EC50 (3 h) > 1000 mg/L (nominal).