Tetrakis(diethyldithiocarbamato-S,S')tellurium

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 Oct 2016 to 30 Nov 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Version / remarks:

17 Jul, 2002

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Version / remarks:

May 2008

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Name of test item (as cited by study report): Tellurium diethyldithiocarbamate
- Batch No.: 60700109
- Production date: 10 Jul 2016
- Expiry date: 10 Jul 2018 (retest date)
- Appearance: Light orange to yellow powder
- Purity: 99.19% (HPLC)
- Water solubility: < 0.1g/L
- Homogeneity: Homogeneous
- Carbon content: 33.33 %

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
The test item was stored in a tightly closed vessel at room temperature (17.0 – 20.4 °C) under dry conditions in the dark.

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

- Source: The sludge was taken from the activation basin of the ESN (Stadtentorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf
- Date of collection: 28 Oct 2016
- Batch No.: 20161028
- Pre-treatment: The sludge was filtrated, washed with tap water (2x), then washed with and re-suspended in test medium. It was then aerated until use. The dry matter was determined as 3700 mg suspended solids/L.

Duration of test (contact time):

28 d

Initial conc.:

59.9 mg/L

Based on:

test mat.

Remarks:

corresponding to 20.0 mg/L DOC (replicate 1).

Initial conc.:

60.3 mg/L

Based on:

test mat.

Remarks:

corresponding to 20.1 mg/L DOC (replicate 2).

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

PREPARATIONS
The medium was prepared from the stock solutions. The stock solution of the positive control was prepared and its DOC was measured. The test vessels were filled with medium and inoculum. Then, all flasks were aerated for 72 hours with purified, CO2-free, moistened air to purge the system of CO2. The test item was added directly, the amounts were calculated from the carbon content of the test item. The amounts of test substance and positive control added to the flasks is tabulated in 'Any other information on materials and methods incl, tables'.

EXPERIMENTAL PARAMETERS
- Test vessels: 2000 mL-SCHOTT-flasks were used as test vessels, 100 mL scrubber flasks as absorbent vessels.
- Flask volume: 1500 mL
- Apparatus blanks: 2, containing mineral medium only
- Blank Controls: 2, containing mineral medium and inoculum
- Positive control: flasks 2, containing positive control, mineral medium and inoculum
- Test flasks: 2, containing test item, mineral medium and inoculum
- Abiotic control: 1, containing test item, mineral medium and HgCl2
- Toxicity control: 1, containing test item, positive control, mineral medium and inoculum
- Inoculum concentration: 25.0 mg/L
- Temperature: 19.5 - 21.6 °C
- pH levels: 7.1 - 7.5; only the Abiotic control had a pH of 6.6 at the end of the test.

APPARATUS
The test vessels were aerated with purified (by activated charcoal), CO2-scrubbed, moistened air. The scrubbing of carbon dioxide was achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To control the absence of CO2, the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels. Magnetic stirrers were used to prevent deposition of inoculum. The emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels. The initial IC value of the 0.25 M NaOH was separately determined in each flask.

SAMPLING
From each front scrubber flask, 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2. On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.

Reference substance:

aniline

Test performance:

See 'Any other information on materials and methods incl. tables'

Key result

Parameter:

% degradation (CO2 evolution)

Value:

6

Sampling time:

28 d

Details on results:

The degree of biodegradation of the test substance reached 6% after 28 days. A detailed overview of the test results is provided in 'Any other information on restults incl. tables'. The degradation in the toxicity control after 14 days was 39.2%.

Results with reference substance:

Degradation behaviour of positive control was 70 % after 9 days. See 'Any other information on results incl. tables'.

Table: Degradation values in %

Day	Positive Control 1	Positive Control 2	Positive Control Mean	Test 1	Test 2	Test Mean	Abiotic Control	Toxicity Control
2	0.1	-1.9	-0.9	1.7	2.5	2.1	0.2	0.4
4	33.9	15.9	24.9	0.8	2.9	1.9	1.1	13.6
7	66.1	42.6	54.3	-0.9	1.1	0.1	2.2	28.6
9	76.0	64.0	70.0	-1.7	0.1	-0.8	2.9	34.2
11	83.8	78.3	81.1	-2.4	-0.5	-1.5	3.7	38.5
14	87.0	82.8	84.9	-2.8	-1.7	-2.2	4.6	39.2
18	88.0	85.9	86.9	0.1	0.5	0.3	5.5	40.8
23	88.0	85.0	86.5	0.0	1.2	0.6	6.5	41.3
29	87.4	85.9	86.6	6.4	5.4	5.9	8.5	42.6

 

Table: IC values in mg/L of apparatus blanks, blank controls, front scrubber

Day	Appratus blank 1	Apparatus blank 2	Blank Control 1	Blank Control 2
0	3.10	3.38	3.21	3.48
2	3.74	5.27	11.58	9.52
4	5.20	7.33	21.93	20.75
7	6.70	9.33	36.95	34.76
9	7.69	12.06	44.95	46.42
11	9.83	15.17	*54.16	56.10
14	11.26	16.49	63.36	63.29
18	13.88	19.28	71.15	71.48
23	17.63	23.18	82.83	81.10
29	22.64	32.22	92.52	92.17

* Due to a software error of the carbon analyser on day 11 no IC value of Blank Control 1 was measured. Therefore, the mean of Blank Control 1 from day 9 and day 14 was taken for evaluation.

Table: IC values in mg/L of positive control, test flasks, front scrubber

Day	Positive Control 1	Positive Control 2	Test 1	Test 2	Abiotic Control	Toxicity Control
0	3.23	3.32	4.06	3.05	3.92	3.24
2	10.87	4.79	16.47	17.89	5.77	12.95
4	125.02	70.09	24.46	30.03	10.26	104.33
7	240.26	167.56	33.68	39.00	15.41	213.13
9	283.17	245.71	40.98	45.72	19.77	259.56
11	319.81	302.69	48.18	53.20	24.80	298.35
14	341.19	327.76	55.28	57.48	29.24	314.07
18	355.31	348.66	72.46	72.50	35.21	334.70
23	368.96	359.48	82.80	85.48	42.35	351.86
29	381.93	375.56	110.55	107.63	53.40	373.23

 

Table: IC values in mg/L of blank controls, apparatus blanks, back scrubber

Day	Appratus blank 1	Apparatus blank 2	Blank Control 1	Blank Control 2
0	8.07	2.96	3.04	3.40
29	3.07	3.21	3.50	3.30

Table: IC values in mg/L of positive control, test flasks, back scrubber

Day	Positive Control 1	Positive Control 2	Test 1	Test 2	Abiotic Control	Toxicity Control
0	3.98	3.33	3.29	3.31	2.78	3.23
29	3	3.58	6.69	5.75	2.85	3.62

 

Table: Net IC-values in mg/L of front scrubber flasks

Day	Blank Control 1	Blank Control 2	Positive Control 1	Positive Control 2	Test 1	Test 2	Abiotic Control	Toxicity Control
0	3.2	3.5	3.2	3.3	4.1	3.1	3.9	3.2
2	10.3	8.3	9.6	3.5	15.2	16.7	4.5	11.7
4	18.9	17.7	122.0	67.1	21.4	27.0	7.2	101.3
7	32.2	30.0	235.5	162.8	28.9	34.2	10.6	208.4
9	38.3	39.8	276.5	239.1	34.3	39.1	13.1	252.9
11	44.9	46.8	310.6	293.4	38.9	43.9	15.5	289.1
14	52.7	52.7	330.6	317.1	44.6	46.8	18.6	303.4
18	57.8	58.1	342.0	335.3	59.1	59.2	21.9	321.4
23	65.7	63.9	351.8	342.3	65.6	68.3	25.2	334.7
29	68.3	68.0	357.7	351.4	86.4	83.4	29.2	349.0

 

Table: Net IC-values in mg/L of back scrubber flasks

Day	Blank Control 1	Blank Control 2	Positive Control 1	Positive Control 2	Test 1	Test 2	Abiotic Control	Toxicity Control
0	3	3.4	4	3.3	3.3	3.3	2.8	3.2
29	5.9	5.7	5.4	6	9.1	8.1	5.2	6

  

Table: Emitted carbon in mg/L

Day	Blank Control 1	Blank Control 2	Positive Control 1	Positive Control 2	Test 1	Test 2	Abiotic Control	Toxicity Control
2	0.47	0.32	0.42	0.01	0.74	0.90	0.04	0.56
4	1.03	0.93	7.76	4.16	1.14	1.57	0.22	6.41
7	1.87	1.71	15.02	10.31	1.61	2.20	0.43	13.26
9	2.25	2.32	17.49	15.09	1.94	2.31	0.59	15.98
11	2.64	2.75	19.46	18.37	2.21	2.59	0.74	18.10
14	3.10	3.08	20.51	19.67	2.54	2.74	0.92	18.81
18	3.39	3.39	21.00	20.58	3.41	3.48	1.11	19.72
23	3.83	3.71	21.38	20.79	3.78	4.00	1.30	20.33
29	4.14	4.06	21.60	21.29	5.37	5.19	1.70	21.16

 

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on materials and methods incl. tables'

Interpretation of results:

under test conditions no biodegradation observed

Description of key information

Not readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The biodegradation potential of the test substance in water was determined in a screening study according to OECD TG 301B (CO2-Evolution Test) and in compliance with GLP criteria (LAUS GmbH, 2017). In this study, 20 mg/L test substance (expressed as DOC) was inoculated with activated sludge from predominantly domestic sewage for 28 days under aerobic conditions in the dark. During the incubation period degradation was followed by determining the carbon dioxide produced. After the 28-day incubation period 6% of the test substance was biodegraded. The 10-day-window was not detected. Therefore, the test substance is classified as not readily biodegradable.