Reaction products of N,N'-ethane-1,2-diylbis(1,3-propanediamine), cyclohexane, peroxidized 4-butylamino-2,2,6,6-tetramethylpiperidine and 2,4,6-trichloro-1,3,5-triazine

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:

1997-05-30 - 1997-11-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study (OECD test guideline 209)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Analytical monitoring:

not specified

Details on sampling:

no data

Vehicle:

yes

Details on test solutions:

Five stock solutions of the test item were prepared. Each stock solution was prepared by adding the appropriate amount of test substance (0.5008 g, 0.1573 g, 0.0491 g, 0.0153 g, and 0.0048 g) into a 1-liter (L) volumetric flask and then bringing to volume with deionized water. The contents were shaken and ultrasonicated. A stable emulsion was observed in each stock solution.

Test organisms (species):

activated sludge

Details on inoculum:

Inoculum Source: Sewage treatment plant (Jupiter, Florida)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Details on test conditions:

TEST SYSTEM/TEST MEDIUM
- Source: Activated sludge from a sewage treatment plant (4 L), conditioned for testing
- Water: Dechlorinated drinking water
- Nutrient solution (synthetic sewage feed): 16 g Peptone, 11 g Meat extract, 3.0 g Urea, 0.7 g NaCl, 0.4 g CaCl2~2 H2O, 0.2 g MgSO4~7 H2O, 2.8 g K2HPO4
- Vessels : 1 L flasks, aerated (approximately 0.5 L/minute)
- Fill volume 500 mL
- Synthetic sewage feed: 16 mL
- Sludge in the test bottles: 200 mL inoculum
- Stock reference solution: 100 mL
- Test water: 184 mL
- Twelve 1L test flasks were used at each contact time. Two flasks were used as control blanks, five flasks were used for the test substance, and five flasks were used for the reference substance.

OTHER TEST CONDITIONS
- Temperature: 20 +/- 2°C

EFFECT PARAMETERS MEASURED
- Oxygen consumption per hour in mg/L
- After 30 minutes and 3 hours of aeration, the first sample was taken for oxygen measurement over a period of about 10 minutes
- At each sampling event, the whole flask was sacrificed and the content was transferred into a BOD bottle for measurement of the oxygen consumption (15 minute interval to ensure a constant contact time for all the samples)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Test concentrations: 0.96, 3.06, 9.82, 31.4 and 100 mg/L
- Reference substance: 0.65, 2.28, 7.96, 27.8, and 97.4 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

0.5 h

Dose descriptor:

IC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Details on results:

The oxygen consumption of the activated sludge was only slightly inhibited (<10%) at the test concentration range of 1 - 100 mg/L. Therefore, the EC50 of the test substance can be concluded to be greater than 100 mg/L.
The test substance is non-inhibitory to the bacteria in activated waste water at contact times of 30 minutes and 3.0 hours.

Results with reference substance (positive control):

IC50 (3h) of the reference substance 3,5-Dichlorophenol: 8.01 mg/L.
IC50 (0.5h) of the reference substance 3,5-Dichlorophenol: 13.3 mg/L.

The test was regarded as valid since the difference between the two controls was <15% and EC50 values of the 3,5-dichlorophenol were found to be within the 5 to 30 mg/L range.

Executive summary:

In a respiration inhibition test activated sludge was inoculated with the test item (as described in section 1.2) at nominal concentrations of 0.96, 3.06, 9.82, 31.4 and 100 mg test item/L. The incubation period was 3 hours. A negative control and a positive control was included in the study. In this study an IC50 (3h) > 100 mg/L / IC50 (0.5h) > 100 mg/L was determined for the test substance. The positive control substance 3,5-Dichlorophenol induced the appropriate response. This study was performed in line with OECD requirements for testing toxicity to microorganisms.

Description of key information

No relevant inhibitory effects on microorganisms were measured in a respiration inhibition test with activated sludge (IC50 (3h) > 100 mg/mL). 

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

The toxicity to microorganisms was assessed in a respiration inhibition test according to OECD guildeline 209. Activated sludge was inoculated with the test substance at nominal concentrations of 0.96, 3.06, 9.82, 31.4 and 100 mg test substance/L. The incubation period was 3 hours. A negative control and a positive control was included in the study. In this study an IC50 (3h) > 100 mg/L / IC50 (0.5h) > 100 mg/L was determined for the test substance. The positive control substance 3,5-Dichlorophenol induced the appropriate response.Taking the low water solubility of the test item into account, it can be concluded that it has no inhibitory effect on microorganisms.