3-(triethoxysilyl)propiononitrile

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:

2009-09-04 to 2009-09-04

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

GLP compliance:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Known volume of test substance, Milli-RO water, synthetic sewage feed (16 ml) and activated sludge (200 ml) were mixed and made up to 500 ml with Milli-RO water in a 1 litre bottle.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Preparation of inoculum for exposure: the sludge was coarsely sieved then washed

- Initial biomass concentration: 3.8 g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Post exposure observation period:

Oxygen consumption was measured and recorded for approximately 10 minutes. During measurement, the sample was not aerated but continuously stirred on a magnetic stirrer.

Test temperature:

18.9-19.8°C

pH:

8.2

Details on test conditions:

TEST SYSTEM

- Test vessel:

- Material, size, headspace, fill volume: glass, 300ml oxygen bottles, 1L test bottles

- Aeration: continuous during the 3 hour test period

- No. of vessels per concentration (replicates): two

- No. of vessels per control (replicates): two

- Biomass loading rate: 100 mg/L


TEST MEDIUM / WATER PARAMETERS

- Source/preparation of dilution water: Tap-water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon and ion-exchange cartridges (Milli-Q)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : After the 3-hour contact time, a well mixed sample of the contents of the reaction mixture was poured into a 300 ml oxygen bottle, and the flask was sealed with an oxygen electrode connected to a recorder, forcing the air out of the vessel. WTW inolab Oxi 730 supplied with a WTW CellOx 325 oxygen electrode, electrolyte type ELY/G.

TEST CONCENTRATIONS

- Spacing factor for test concentrations: 100 mg/L only

- Justification for using less concentrations than requested by guideline: Performance of a limit concentration at 100 mg/l is acceptable, because 100 mg/l exceeds the expected concentration in a Sewage Treatment Plant.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The two controls had a difference in respiration rate of 0%, which is less than the 15% limit required by the guideline for a valid study.

Results with reference substance (positive control):

A positive control test with 3, 5-Dichlorophenol yielded an EC50 of 7.2 mg/L, which is within the accepted range of 5 to 30 mg/l required by the guideline for a valid study.

Table 1: Results of the activated sludge respiration inhibition test

Test sample	Loading rate (mg/l)	Oxygen conc. at start (mg O2/l)	Oxygen consumption (mg O2/l/h)	% Inhibition respiration rate	pH
Initial control	0	7.2	34	-	8.4
Final control	0	7.0	34	-	8.3
3-(triethoxysilyl)propiononitrile replicate (1)	100	5.4	47	-38 (a)	8.2
3-(triethoxysilyl)propiononitrile replicate (2)	100	5.4	47	-38 (a)	8.2
3,5-dichlorophenol	5	-	-	43	-
	12	-	-	61	-
	30	-	-	67	-

 

Note: (a) A negative value indicates stimulation of the respiration rate of the sludge

Validity criteria fulfilled:

yes

Conclusions:

An activated sludge respiration inhibition 3hr EC50 value of >100 mg/l (loading rate) was determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP. This indicates that the test substance was not toxic to waste water (activated sludge) bacteria at a loading rate of 100 mg/l.

Description of key information

Toxicity to microorganisms: ASRI 3 hour EC₅₀ >100 mg/L (loading rate) (OECD 209)

Additional information

An activated sludge respiration inhibition 3 h EC₅₀ value of >100 mg/L (loading rate) was determined for the substance in a reliable study conducted according to an appropriate test protocol and in compliance with GLP. The result indicates that the test substance was not toxic to wastewater (activated sludge) bacteria at a loading rate exceeding a value of 100 mg/L.