Ethylene bis(3-mercaptopropionate)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

toxicity control from ready biodegradation test

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Test organisms (species):

activated sludge

Details on inoculum:

- Source of inoculum/activated sludge: Liede STP of Guangzhou
- Preparation of inoculum for exposure: coarse particles were removed; sludge was washed with mineral medium, after sedimentation, sludge was resuspended in mineral medium
- Pretreatment: none
- Concentration of sludge: 4.0 g dry solid/L

Test type:

static

Water media type:

freshwater

Total exposure duration:

28 d

Nominal and measured concentrations:

31 mg/L

Details on test conditions:

TEST CONDITIONS
- Composition of medium: potassium phosphate buffer solution with Ca, Mg, and Fe added
- Test temperature: 22+-2 °C
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Number of culture flasks/concentration: 2

SAMPLING
- Sampling frequency: Days 2, 5, 7, 11, 14, 19, 25, 29
- Sampling method: Ba(OH)2 trap

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

Duration:

14 d

Dose descriptor:

IC10

Effect conc.:

31 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

Toxicity control (14 d): 75.4% degr.

Validity criteria fulfilled:

yes

Conclusions:

no inhibition of activated sludge respiration at 31 mg/L

Executive summary:

The biodegradation of GDMP was investigated over a 28-day period in a CO2 Evolution Test according to OECD guideline 301 B. The test medium was inoculated with activated sludge from a sewage treatment plant (secondary of Liede Sewage Treatment Plant of Guangzhou). The rate of degradation was monitored by measuring the carbon dioxide produced over the 28-d period. The test item was tested with a concentration of 31 mg/L in duplicates, corresponding to a carbon content (TOC) of 12.3 mg C/L in the test vessels. The biodegradation of the test item was followed by titrimetric analyses of the quantity of CO2 produced by the respiration of bacteria. The degradation was finished on day 28 by acidification, the last titration was made on day 29. After the soluble CO2 was turned out over a period of 24 h.

The percentage CO2 production was calculated in relation to the theoretical CO2 (ThCO2) of the test item. The biodegradation was calculated for each titration time.

To check the activity of the test system sodium benzoate was used as functional control. The percentage of degradation of the functional control reached the pass level of 60 % after 10 days.

In the toxicity control containing both test and reference item a biodegradation rate of 75.4% occurred within 14 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.

 

 

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

31 mg/L

Additional information

The biodegradation of GDMP was investigated over a 28-day period in a CO2 Evolution Test according to OECD guideline 301 B. The test medium was inoculated with activated sludge from a sewage treatment plant (secondary of Liede Sewage Treatment Plant of Guangzhou). The rate of degradation was monitored by measuring the carbon dioxide produced over the 28-d period. The test item was tested with a concentration of 31 mg/L in duplicates, corresponding to a carbon content (TOC) of 12.3 mg C/L in the test vessels. The biodegradation of the test item was followed by titrimetric analyses of the quantity of CO2 produced by the respiration of bacteria. The degradation was finished on day 28 by acidification, the last titration was made on day 29. After the soluble CO2 was turned out over a period of 24 h.

The percentage CO2 production was calculated in relation to the theoretical CO2 (ThCO2) of the test item. The biodegradation was calculated for each titration time.

To check the activity of the test system sodium benzoate was used as functional control. The percentage of degradation of the functional control reached the pass level of 60 % after 10 days.

In the toxicity control containing both test and reference item a biodegradation rate of 75.4% occurred within 14 days. The biodegradation of the reference item was not inhibited by the test item in the toxicity control.