Reaction mass of 1,2,2,6,6-pentamethylpiperidin-4-yl hexadecanoate and 1,2,2,6,6-pentamethylpiperidin-4-yl octadecanoate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 July 2012 - 24 July 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to internationally accepted guidelines and to GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Reaction mass of 1,2,2,6,6-pentamethylpiperidin-4-yl hexadecanoate and 1,2,2,6,6-pentamethylpiperidin-4-yl octadecanoate

EC Number:

700-792-4

Molecular formula:

C26H51NO2, C28H55NO2

IUPAC Name:

Reaction mass of 1,2,2,6,6-pentamethylpiperidin-4-yl hexadecanoate and 1,2,2,6,6-pentamethylpiperidin-4-yl octadecanoate

Details on test material:

- Name of test material (as cited in study report): T-1640L
- Physical state: White to pale yellow solid
- Analytical purity: 98.74%
- Purity test date: 20 May 2011
- Lot/batch No.: 10121
- Expiration date of the lot/batch: 12 April 2013
- Storage condition of test material: Refrigerated in the dark

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Weigh compound directly to required test bottles
-- Evidence of undissolved material (e.g. precipitate, surface film, etc):

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Laboratory culture: sample was maintained under aerobic conditions until required
- Method of cultivation:
- Preparation of inoculum for exposure:
On the day of collection, an aliquot (10 mL) of the activated sludge was filtered through a dried and preweighed Whatman GF/C filter paper, which was then dried again at approximately 105°C for at least one hour, allowed to cool in a desiccator and reweighed.
The mixed liquor suspended solids (MLSS) content of the activated sludge was then calculated. Synthetic sewage (50 mL/L) was added to the stock of activated sludge and this was aerated overnight.
- Pretreatment:
On the day of the test, the MLSS content of the sludge was determined (in triplicate) and adjusted to 4 g/L by the addition of tap water. The pH and temperature of the sludge were also measured. Aliquots (200 mL) were then added to each mixture to give a final MLSS
concentration of 1.6 g/L.

- Initial biomass concentration:

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

20 ± 2°C

pH:

7.0

Dissolved oxygen:

6.38 - 8.00 (initial mgO2/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: Bottle
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass, 500 mL
- Aeration: aerator connected to lab supply of oil-free compressed air (one L/min.)
- Renewal rate of test solution (frequency/flow rate):
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5
- No. of vessels per vehicle control (replicates):
- Biomass loading rate:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reverse osmosis water

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod:
- Light intensity:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Oxygen consumption measured at one minute intervals for 15 minutes post-exposure

TEST CONCENTRATIONS
- Spacing factor for test concentrations: x10
- Range finding study: no
- Test concentrations: 10, 100, 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

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

Remarks:

respiration rate

Remarks on result:

other: Could not be calculated so must be > highest conc. tested

Effect concentrations 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: The three-hour EC50 for 3,5-DCP was 11.9 mg/L
- Other: Validity criteria relating to controls was satisfied (specific respiration rate ≥20 mgO2/gh) and CV≤30%

Any other information on results incl. tables

Measurements of the pH of the aqueous stock solutions of the synthetic sewage, the test and reference substances and of the sample of activated sludge (4 g/L) before the start of the test are given below.

Preparation              pH

Synthetic Sewage      7.47

3,5 -DCP stock        7.24 

Activated sludge        7.05

Sludge respiration rates were progressively reduced in the presence of increasing concentrations of 3,5-DCP. The three-hour 50% effect concentration (EC50) for 3,5-DCP was calculated to be 11.9 mg/L (95% confidence). The mean specific respiration rate of the control cultures established was 23.4 mgO2/gh with a coefficient of variation of 20.3%.

Applicant's summary and conclusion

Conclusions:

T-1640L did not significantly inhibit the respiration rates of the samples of activated sludge.
Consequently the EC50 for inhibition could not be calculated but must be >1000 mg/L, the
highest concentration tested in this study. The no observed effect concentration (NOEC) for T-1640L was 1000 mg/L.
The three-hour EC50 for 3,5-DCP (11.9 mg/L) fulfilled the validity criterion relating to sensitivity to inhibition (acceptable EC50 range 2 to 25 mg/L). The validity criterion relating to the respiration rates in the control (specific respiration rate ≥20 mgO2/gh and a coefficient
of variation of ≤30%) was also satisfied.