4,4'-[(1,10-dioxodecane-1,10-diyl)bis(oxy)]bis(2,2,6,6-tetramethylpiperidine-1-oxidanyl)

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Report date:

1995

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

adopted April 4, 1984

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L133

Version / remarks:

adopted May 30, 1988.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1,10-bis(2,2,6,6-tetramethyl-1-piperidinyloxy)-1,10-dioxodecane

EC Number:

417-440-8

EC Name:

1,10-bis(2,2,6,6-tetramethyl-1-piperidinyloxy)-1,10-dioxodecane

Cas Number:

2516-92-9

Molecular formula:

C28 H50 N2 O6

IUPAC Name:

bis(1-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl) decanedioate

Details on test material:

Identification code (lab) = TKA 40075

Sampling and analysis

Analytical monitoring:

not required

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The test substance was hardly soluble in water and therefore ca. 100 mg TKA 40075 (GU 10-415) was added quantitatively to a test vessel (final concentration ca. 200 mg/l). Addition of TKA 40075 (GU 10-415) to a test vessel was performed in duplicate.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Name and location of sewage treatment plant where inoculum was collected: Municipal sewage treatment plant: 'Waterschap de Dommel', 's-Hertogenbosch, the Netherlands.
Number of micro-organisms was determined as the amount of Mixed Liquor Suspended Solids (MLSS) per litre test medium.
The sludge was coarsely sieved and washed with tap-water. A small amount of the sludge was weighed and dried at ca. 105°C. From this result the amount of suspended solids was calculated: the level was 3.7 g/l of sludge. The batch of sludge was used on subsequent days (maximum four days), therefore 50 ml of synthetic sewage feed was added to each litre of activated sludge at the end of each working day. The sludge was kept aerated at 20 + 2°C until use. Before use the pH was checked
(7.2).

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Test conditions

Test temperature:

20°C

pH:

7.1

Nominal and measured concentrations:

The test substance was hardly soluble in water and therefore ca. 100 mg TKA 40075 (GU 10-415) was added quantitatively to a test vessel (final concentration ca. 200 mg/l).

Details on test conditions:

TEST SYSTEM
- Test vessel: All glass, 500 ml beakers and 300 ml oxygen bottles.
- Aeration: yes, during contact time
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 3.7 g/L
- Nutrients provided for bacteria: Synthetic sewage feed
16 g peptone
11 g meat extract
3 g urea
0.7 g NaCl
0.4 g CaCl2.2H20
0.2 g MgS04 .7H2O
2.8 g K2HPO4
Dissolved in 1 1 Milli-Q water and filtered. The pH was 7.1. The nutrient solution was autoclaved and thereafter stored at 4°C for 9 days before use. Before use it was mixed thoroughly.
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
Tap-water purified by reverse osmosis and subsequently passed over activated carbon and ion-exchange cartridges (Millipore Corp., Bedford, Mass.,USA).


OTHER TEST CONDITIONS
- Adjustment of pH: no

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol (Aldrich, Cat. no. D 7,060-0, purity 97%). Three concentrations were tested: 3.2, 10 and 32 mg/l.

Results and discussion

Effect concentrations

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

No significant inhibition in respiration rate of the sludge (>10%) was recorded after addition of ca. 100 mg TKA 40075 (GU 10-415) to the test medium, final concentration ca. 200 mg/l.
The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.
Thus, under the conditions of the present test the EC50 was greater than 200 mg/l.
Note that the concentration tested was greater than the maximum solubility of TKA 40075 (GU 10-415) in water (< 0.5 mg/l at 20°C). Therefore, the test concentration is not expected to occur in water after a spill or other discharge type situation.

Acceptability test: acceptable
The mean respiration rate of control 1 and 2 was 38 mg 02/l/hr. The difference between the controls was 8%.
The mean respiration rate of control 3 and 4 was 38 mg 02/l/hr. The difference between the controls was 3%.

Results with reference substance (positive control):

EC50 of 3,5-dichlorophenol = ca. 6 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this present test (OECD 209) TKA 40075 (GU 10-415) was not toxic to waste-water bacteria.

Executive summary:

The influence of TKA 40075 (GU 10-415) on the respiration rate of activated sludge was investigated in this study.

The study procedure was based on OECD Guideline No. 209, adopted April 4, 1984 and EEC Directive 67/548 amended November 18, 1987 (87/302), Part C, Publication No. L133, adopted May 30, 1988.

The test substance was hardly soluble in water and therefore ca. 100 mg TKA 40075 (GU 10-415) was added quantitatively to a test vessel (final concentration ca. 200 mg/l). Addition of TKA 40075 (GU 10-415) to a test vessel was performed in duplicate.

No significant inhibition in respiration rate of the sludge (>10%) was recorded after addition of ca. 100 mg TKA 40075 (GU 10-415) to the test medium, final concentration ca. 200 mg/l.
The duplicate measurement confirmed the result of the first measurement. Therefore no further testing was needed.

Thus, under the conditions of the present test the EC50 was greater than 200 mg/l.
Note that the concentration tested was greater than the maximum solubility of TKA 40075 (GU 10-415) in water (< 0.5 mg/l at 20°C). Therefore, the test concentration is not expected to occur in water after a spill or other discharge type situation.

The respiration rates of controls were within 15% of each other and the EC50 of the reference substance, 3,5-dichlorophenol, was estimated to be 6 mg/l. Therefore, the test was considered to be valid.

In conclusion, under the conditions of this present test TKA 40075 (GU 10-415) was not toxic to waste-water bacteria.