Methyl toluene-4-sulphonate

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:

September 01, 2017 to September 29, 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

Commission Regulation 440/2008/EC, Method C.4- D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

No further details specified in the study report.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Species/Origin: Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Rossdorf, Germany.
Conditioning: The aerobic activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was done three times. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined.
Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per litre were mixed with test water and aerated overnight. This suspension was used for the experiment.

Duration of test (contact time):

28 d

Initial conc.:

25 mg/L

Based on:

test mat.

Details on study design:

Type and Size: Manometric Test System with test flasks containing a volume of approximately 500 mL.
Apparatus: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany
Principle: The test flasks prepared according paragraph 6.6 were incubated at 22°C ± 1°C. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB/BODSensor-System, Aqualytic Dortmund, Germany. The test flasks were closed gas-tight by a measuring head.
Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide. The amount of O2 consumed by the activated sludge was calculated from the decrease of pressure in the reaction vessel.
Identification: Each test unit was uniquely identified with the study number, treatment and replicate number.

Test Conditions
Surrounding Type: Climatised chamber
Temperature: 22°C ± 1°C
Light Conditions: Darkness
pH-Value of Test Solutions: 7.6 (measured at the start of the test); 7.0 to 7.6 (measured at the end of the test)

Course of the Test
Preparation of Test Flasks: The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used.
Incubation: The closed test flasks were incubated in a climatised chamber under continuous stirring. The consumption of oxygen was determined by measuring the change of pressure in the flasks. Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide.
Test Duration: 28 days

Test Parameters
Measurement of Oxygen: The change of pressure in the test flasks was measured by means of a manometric method (BSB/BODSensor-System, Aqualytic Dortmund, Germany) each day.
Temperature: The temperature was recorded by means of the automated software AMR Wincontrol©.
pH-Value: pH-values were measured in procedure control, a separately prepared test flask with test item (to prevent loss of test item in the test flasks) and a separately prepared test flask without test item (control) at test start and in all flasks at the end of the test, except in the abiotic and toxicity control, using a pH-electrode WTW pH 340i.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

28 d

Details on results:

Biodegradation of Test Item
Percentage Biodegradation: The 10-day windows began on day 6 after application, the mean value was calculated to be 11% biodegradation. Therefore, the end of the 10-day window was at day 16. The mean biodegradation percentage based on ThODNH4 at the end of the 10-day window was 58%; the criterion of the 10 day window was not passed. The mean biodegradation percentage at the end of the 28-day exposure period was 73%.
Conclusion: The degradation rate of PTSM did not reach 60% within the 10-day window, but after 28 days.
Therefore, PTSM is considered to be readily biodegradable, but failing 10-day window.

Biodegradation of Reference Item Sodium Benzoate
Percentage Biodegradation: The reference item sodium benzoate was sufficiently degraded to 93% after 14 days and to 102% after 28 days of incubation.
Conclusion: The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Biodegradation in the Toxicity Control
Percentage Biodegradation: In the toxicity control containing both, the test item and the reference item sodium benzoate, 45% biodegradation was noted within 14 days and 68% biodegradation after 28 days of incubation.
Conclusion: According to the test guidelines the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Abiotic Control
Oxygen Demand: The oxygen demand in the abiotic control was 0 mg/L during the test duration. There was no use to correct the degradation of the test item and toxicity control.

Cumulative Biochemical Oxygen Demand (mg O₂/L) in Test Flasks during the Test Period of 28 Days

Time (days)	Flask No.
	1	2	3	4	5	6	7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28	0 0 5 15 15 20 40 50 60 60 70 75 85 90 95 100 100 105 105 105 110 110 115 115 120 120 120 125	0 0 0 15 15 20 35 45 60 65 75 85 95 105 110 115 115 120 120 125 125 130 130 135 135 140 145 145	0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0	0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0	40 70 95 110 130 135 140 145 145 150 150 155 155 160 160 165 165 165 165 165 165 170 170 170 170 170 175 175	0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0	10 85 110 115 120 125 130 130 130 130 135 145 160 160 165 170 170 170 170 180 185 190 195 200 210 215 225 240

Flasks 1 and 2: PTSM

Flask 3 and 4: inoculum control

Flask 5: reference (procedure control)

Flask 6: abiotic control

Flask 7: toxicity control

 

Percentage Biodegradation of Test Item, of Sodium Benzoate and of the Toxicity Control based on THOD_NH4

Time (days)	Percentage Biodegradation 1
	PTSM^1		Sodium Benzoate^2	Toxicity control^1,2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28	0 0 3 8 8 11 22 27 32 32 38 40 46 48 51 54 54 57 57 57 59 59 62 62 65 65 65 67	0 0 0 8 8 11 19 24 33 35 41 46 52 57 60 62 62 65 65 68 68 71 71 73 73 76 79 79	23 41 55 64 76 78 81 84 84 87 87 90 90 93 93 96 96 96 96 96 96 99 99 99 99 99 102 102	3 24 31 32 34 35 37 37 37 37 38 41 45 45 47 48 48 48 48 51 52 54 55 56 59 61 64 68

¹THOD_NH4of PTSM: 1.805 mg O₂/mg test item

¹THOD_NH4of sodium benzoate: 1.666 mg O₂/mg reference item

 

pH-Values at the End of the Test

Flask No.	Treatment	pH-Value
1 2 3 4 5	PTSM PTSM Inoculum control Inoculum control Reference item (procedure control)	7.0 7.0 7.6 7.6 7.6

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached
within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.
The mean biodegradation of 10% of PTSM was reached at day 6 (ThODNH4). At the end of the 10-day window at day 16, the mean degradation of PTSM was
58% (ThODNH4) and therefore the 10 day window criterion was not passed. The mean biodegradation at test end after 28 days was 73% (ThODNH4).
Therefore, PTSM is considered to be readily biodegradable, but failing 10-day window.

Executive summary:

Summary

Title: PTSM: Ready Biodegradability in a Manometric Respirometry Test

 

Guidelines: This study was designed to comply with the following methods:

− Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

− OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

 

Material and Methods:

Test Species: Aerobic activated sludge (microorganisms from a domestic wastewater treatment plant) was supplied by the sewage treatment plant of Rossdorf, Germany.

 

Test Design: The test item PTSM was investigated for its ready biodegradability in a Manometric respirometry test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

 

Endpoints: Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.

 

Test Item Loading Rate (initial concentration in medium C₀): 102.5 mg/L corresponding to an oxygen demand of about 184.9 mg/L (ThOD_NH4)

 

Reference Item: Sodium Benzoate

Reference Item Loading Rate: 103.3 mg/L corresponding to an oxygen demand of about 172.1 mg/L (ThOD_NH4)

 

Test Conditions: 22°C ± 1°C, darkness

 

Results:

Biodegradation of PTSM: The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.

The mean biodegradation of 10% of PTSM was reached at day 6 (ThOD_NH4). At the end of the 10-day window at day 16, the mean degradation of PTSM was 58% (ThOD_NH4) and therefore the 10 day window criterion was not passed. The mean biodegradation at test end after 28 days was 73% (ThOD_NH4).

Therefore, PTSM is considered to be readily biodegradable, but failing 10-day window.

 

Biodegradation of Sodium Benzoate: The reference item sodium benzoate was sufficiently degraded to 93% after 14 days and to 102% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

 

Biodegradation of the Toxicity Control: In the toxicity control containing both, the test item and the reference item sodium benzoate, 45% biodegradation was noted within 14 days and 68% biodegradation after 28 days of incubation. According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Description of key information

PTSM is considered to be readily biodegradable, but failing 10-day window.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Additional information

Summary

Title: PTSM: Ready Biodegradability in a Manometric Respirometry Test

 

Material and Methods:

Test Species: Aerobic activated sludge (microorganisms from a domestic wastewater treatment plant) was supplied by the sewage treatment plant of Rossdorf, Germany.

 

Test Design: The test item PTSM was investigated for its ready biodegradability in a Manometric respirometry test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

 

Endpoints: Degradation rate of test item calculated by the oxygen consumption of the aerobic activated sludge microorganisms after 28 days of incubation.

 

Test Item Loading Rate (initial concentration in medium C₀): 102.5 mg/L corresponding to an oxygen demand of about 184.9 mg/L (ThOD_NH4)

 

Reference Item: Sodium Benzoate

Reference Item Loading Rate: 103.3 mg/L corresponding to an oxygen demand of about 172.1 mg/L (ThOD_NH4)

 

Test Conditions: 22°C ± 1°C, darkness

 

Results:

Biodegradation of PTSM: The criterion for ready biodegradability under the conditions of a manometric respirometry test is the degradation of the test item of at least 60%, reached within a 10-day window; the 10-day window starts when the degradation of the test item reaches at least 10% degradation.

The mean biodegradation of 10% of PTSM was reached at day 6 (ThOD_NH4). At the end of the 10-day window at day 16, the mean degradation of PTSM was 58% (ThOD_NH4) and therefore the 10 day window criterion was not passed. The mean biodegradation at test end after 28 days was 73% (ThOD_NH4).

Therefore, PTSM is considered to be readily biodegradable, but failing 10-day window.

 

Biodegradation of Sodium Benzoate: The reference item sodium benzoate was sufficiently degraded to 93% after 14 days and to 102% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

 

Biodegradation of the Toxicity Control: In the toxicity control containing both, the test item and the reference item sodium benzoate, 45% biodegradation was noted within 14 days and 68% biodegradation after 28 days of incubation. According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.