Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

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:

other: As all validation criteria are fulfilled the present study is valid without restrictions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: In addition the instructions of the OECD series on testing and assessment, no. 23: Guidance document on aquatic toxicity testing of difficult substances and mixtures" (ENV/JM/MONO(2000)6) were followed.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

EC Number:

404-310-0

EC Name:

Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

Cas Number:

10591-85-2

Molecular formula:

C30H28N2S4

IUPAC Name:

N,N-dibenzyl[(dibenzylcarbamothioyl)disulfanyl]carbothioamide

Details on test material:

- Name of test material (as cited in study report): Linkwell TBzTD -Tetrakis(phenylmethyl)thioperoxydi(carbothioamid)
- Substance type: mono-constituent substance
- Physical state: solid, powder
- Analytical purity: > 99%
- Lot/batch No.: 08060902
- Expiration date of the lot/batch: 2009-06
- Storage condition of test material: room temperature

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

activated sludge

Details on inoculum:

- Preparation of inoculum for exposure:
A fresh sample of activated sludge from the aeration basin of a municipal sewage treatment plant (Moers, Germany) was collected one day before carrying out the Activated Sludge Respiration Inhibition Test and aerated overnight until usage for the test.
After determination of the suspended solids (dry weight), 5.859 l activated sludge with a dry matter content of 2.048 g/l (which is equivalent to 12 g dry substance I 3 l) was filtered by means of a water jet pump through a filter paper (Schleicher & Schuell, black ribbon 589(1 )).
The sludge was washed twice with mineral medium. Afterwards, 4 g/l activated sludge (dry matter) was suspended in mineral medium, 50 mill synthetic sewage were added and the whole mixture was stirred and aerated (0.5 - 1.0 litre per minute) overnight at 20 ± 2°C. It was not necessary to buffer the pH of the inoculum suspension before use with sodium hydrogencarbonate solution, as, with a measured pH value of 7.87, it was within the required range of 6.0 to 8.0

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:

inoculum suspension 7.87
others: see Table 1

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 l beakers (3-hour contact period) and 300 ml Karlsruher flasks (O2 measurement)
- Aeration: synthetic air, flow meter



OTHER TEST CONDITIONS
- Adjustment of pH:


EFFECT PARAMETERS MEASURED:
Oxygen consumption was followed by continous measurement of the oxygen concentration with an oxygen electrode for up to 10 minutes.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Test concentrations: 10, 32, 100, 320, 1000 mg/l (nominal)

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

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

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values:
As the test substance is not soluble in water, each test concentration was prepared individually, stirred for 24 h and the remaining substance particles were removed by filtration.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 (3 h) = 14.9 mg/l is in the acepted range 5 to 30 mg/l

Any other information on results incl. tables

Table 2: Respiration rates and inhibition of respiration

	Concentration [mg/l]	Respiration rate [mg O2/l/h]	Inhibition [%]
control 1	0	23.4	-
control 2	0	22.8	-
mean control 1 + 2	0	23.1	-
3,5-dichlorophenol	3.2	17.4
3,5-dichlorophenol	10	16.2
3,5-dichlorophenol	32	6.0
Linkwell TBzTD	10	26.5	0
Linkwell TBzTD	32	23.4	0
Linkwell TBzTD	100	27.7	0
Linkwell TBzTD	320	24.0	0
Linkwell TBzTD	1000	20.9	9.5

Applicant's summary and conclusion

Executive summary:

Linkwell TBzTD - Tetrakis(phenylmethyl)thioperoxydi(carbothioamid) was tested in an activated sludge respiration inhibition test after a 3-hour contact period according to the OECD Guideline for Testing of Chemicals, No. 209, to determine whether the test substance is toxic to the microorganisms of activated sludge.

As the test substance is not soluble in water, the test was performed with each test concentration of Linkwell TBzTD - Tetrakis(phenylmethyl)thioperoxydi(carbothioamid) prepared individually, stirred for 24 hand undissolved particles were removed by filtration.

The concentrations tested were 10, 32, 100, 320 and 1000 mg/L. Additionally two inoculum controls, one at the start and one at the end of the experiment, and 3,5-dichlorophenol in concentrations of 3.2, 10 and 32 mg/L as reference substance were tested.

The respiration rate of the activated sludge in the test vessels containing up to 1000 mg/L Linkwell TBzTD - Tetrakis(phenylmethyl)thioperoxydi(carbothioamid) (as test substance preparation) was not inhibited in comparison to the mean of the inoculum controls. Only at 1000 mg/L an inhibition rate of 9,5 % was observed, thus demonstrating that the EC50 is

above the highest tested concentration value.

EC50 > 1000 mg/L (test substance preparation)

The 3-hour EC50 for the reference substance 3,5-dichlorophenol was within the tolerable range of 5 - 30 mg/L. The deviation between the two inoculum controls was 1.8 % and therefore below the maximum permissible deviation of 15 %.