Tetrakis(phenylmethyl)thioperoxydi(carbothioamide)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study performed in compliance with GLP, available as unpublished report, no restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Molecular formula: C30H28N2S4
- Molecular weight: 544.82
- Stability: hydrolyzable
- Storage conditions: in a dark place at room temperature
- Lot No: 80600108
- Purity: 97.7%
- Appearance: white powder

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

The standard activated sludge purchased from Chemicals Evaluation and Research Institute, Japan, on April 17, 2008 was cultured under the conditions of 25±2°C, not less than 5 mg/L of dissolved oxygen concentration and pH 7.0±1.0 at the testing facility. (Sludge No.200417)
Concentration of standard activated sludge (July 8 – July 9, 2008): 1884 mg/L.

Duration of test (contact time):

28 d

Initial conc.:

ca. 30 mg/L

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

- Test temperature: 25 °C
- Volume of test solution: 300 mL
- Test water: prepared by MilliQ
- Test substance concentrations: see table in mat and meth section

Reference substance:

aniline

Test performance:

Based on the results of the reference substance (positive control), it could be concluded that the test performance was good.

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Parameter:

% degradation (test mat. analysis)

Value:

0

Sampling time:

28 d

Results with reference substance:

The degradation rate of aniline calculated from oxygen consumption was not less than 60% (62%) after 14 days of exposure.

	No.	Test solutions	Degradation rate	Degrad. rate (average)
Results of BOD	3	Sludge + test subst	- 14	0*
	4	Sludge + test subst	- 14	0*
	5	Sludge + test subst	- 18	0*
	No.	Test substance	Residual rate (%)	Residual rate (average)	Degradation rate (%)	Degrad. rate (average)
Results of direct determination (LC	3	Sludge + test subst	106	107	-8	0*
	4	Sludge + test subst	106	107	-9	0*
	5	Sludge + test subs	109	107	-9	0*
	6	Water + test subst	101	101	-	-

*minus value was expressed as 0

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

It is concluded from these results that the test substance, TBzTD, was difficult to biodegrade under the test conditions.

The speed of dissolution of TBzTD may be the dominant kinetik parameter to make TBzTD available to the activity of micro-organisms.

Executive summary:

The degradation rate calculated from oxygen consumption was average 0%* after 28 days under the test conditions. The residual rates of TBzTD calculated from direct determination (LC) was average 107% in “sludge + test substance” and 101% in “water + test substance” respectively, and the degradation rate of TBzTD was average 0%*, and the derivative was not recognized. It is concluded from these results that the test substance, TBzTD, was difficult to biodegrade under the test conditions. Further, this test is valid because the difference between the maximum and the minimum of the degradation rate in three “sludge + test substance” calculated from oxygen consumption and direct determination (LC) was less than 20% and the degradation rate of aniline calculated from oxygen consumption was not less than 60% after 14 days’ exposure.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988-08-17 to 1988-10-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study performed in compliance with GLP, available as unpublished report, no restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

EU Method C.5 (Degradation: Biochemical Oxygen Demand)

Version / remarks:

(Directrive EEC 84/488/EEC, Part C, C.5 Modified Sturm test); Equivalent to COUNCIL REGULATION (EC) No 440/2008, C.4. DETERMINATION OF ‘READY’ BIODEGRADABILITY, Carbon dioxide (CO2) Evolution (Modified Sturm Test) (Method C.4-C)

Principles of method if other than guideline:

Instead of measuring the carbon dioxide production by titration the carbon dioxide evolution was measured with a TOCe analyser.

GLP compliance:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): Tetrabenzylthiuramdisulphide (TBeTD; same as TBzTD)
- Substance type: Mono-constituent substance
- Physical state: White powder
- Stability under test conditions: TBzTD is stable from pH 3 to 13.
- Storage condition of test material: 20°C
- Lot/batch No.: 88052615 (OR2)
- Analytical purity: > 95%, technically pure
- Purity test date: > 95%, technically pure

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge was obtained from the rwzi Nieuwgraaf in Duiven (1988-08-18). The rwzi Nieuwgraaf is a domestic sewage treatment plant.
- Preparation of inoculum for exposure: The activated sludge was preconditioned as described in the EEC protocol (4.1.).

Duration of test (contact time):

28 d

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance:

acetic acid, sodium salt

Remarks:

Sodium acetate

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 2

Sampling time:

28 d

Details on results:

Points of degradation plot (test substance): 0 % degradation after 3 d 0 % degradation after 6 d 0 % degradation after 10 d 0 % degradation after 17 d 0 % degradation after 21 d 1 % degradation after 27 d 2 % degradation after 28 d

Results with reference substance:

Points of degradation plot (reference substance):
35 % degradation after 3 d
68 % degradation after 6 d
77 % degradation after 10 d
80 % degradation after 17 d
81 % degradation after 21 d
82 % degradation after 27 d
82 % degradation after 28 d

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

In order to assess ecotoxicological effects of new chemicals, a ready biodegradability test is required which allows preliminary screening. A modified Sturm test on TBzTD is considered as the most suitable test available.

TBzTD is not biodegraded in the sturm test and, therefore should not be classified as readily biodegradable. Because of the insolubility of the test compound and the stringency of the test procedures lack of biodegradation does not, however, mean that TBzTD is not biodegradable but indicates that more work will be needed to establish biodegradability.

Executive summary:

TBzTD is not biodegraded in the modified Sturm test according to Directrive EEC 84/488/EE, Part C. Methods for the determination of ecotoxicity, C. 5 Degradation biotic degradation: Modified Sturm test. Lack of ready biodegradation does not mean that TBzTD is recalcitrant in nature. Firstly, the water insolubility and secondly the stringency of the test procedures could account for the recalcitrance of TBzTD in the Sturm test. TBzTD is probably not toxic in the Sturm test because the endogenous carbon dioxide production is hardly or not affected by TBzTD.

Description of key information

TBzTD is not readily biodegraded in the modified Sturm test according to Directive EEC 84/488/EEC. The lack of biodegradability is probably due to the very low aqueous solubility of TBzTD in the range of 10 to 100 µg/L.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Ready biodegradation - Modified Sturm test

TBzTD is not biodegraded in the modified Sturm test according to Directive EEC 84/488/EE, Part C. Methods for the determination of ecotoxicity, C. 5 Degradation biotic degradation: Modified Sturm test. Lack of ready biodegradation does not mean that TBzTD is recalcitrant in nature. Firstly, the water insolubility and secondly the stringency of the test procedures could account for the recalcitrance of TBzTD in the Sturm test. TBzTD is probably not toxic in the Sturm test because the endogenous carbon dioxide production is hardly or not affected by TBzTD.

OECD guideline 302C inherent biodegradability: modified MITI test (II)

The degradation rate calculated from oxygen consumption was average 0%* after 28 days under the test conditions. The residual rates of TBzTD calculated from direct determination (LC) was average 107% in “sludge + test substance” and 101% in “water + test substance” respectively, and the degradation rate of TBzTD was average 0%*, and the derivative was not recognized. It is concluded from these results that the test substance, TBzTD, was difficult to biodegrade under the test conditions.

The speed of dissolution of TBzTD may be the dominant kinetic parameter to make TBzTD available to the activity of micro-organisms.

TBzTD should, therefore, not be classified as readily biodegradable.