4,4'-thiodiethylene hydrogen -2-octadecenylsuccinate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10th November 2015 - 2nd February 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

GLP compliance:

yes

Specific details on test material used for the study:

Material Batch: LN3833
Purity: 100%
Expiration Date: 26 March 2017
Physical Description: Solid
Storage Conditions: Room temperature, protected from light

Analytical monitoring:

yes

Details on sampling:

dissolved oxygen concentrations were measured every 10 seconds over a 10 minute period or until the DO measurement dropped below 1.0 mg O2/L using a YSI Model 50B-115 Dissolved Oxygen Meter.

Vehicle:

no

Details on test solutions:

The test substance was dosed by direct weight addition.

Test organisms (species):

activated sludge

Details on inoculum:

Activated sludge collected from the Easton Wastewater Treatment Facility, Easton, Maryland on 10 November 2015 was utilized as the inoculum for the test. The Easton facility receives wastes from predominately domestic sources. The sludge was sieved using a 2 mm screen and allowed to settle for 30 minutes. The supernatant above the settled solids was removed and the total suspended solids (TSS) concentration of the settled sludge was determined. Total suspended solids in the settled sludge were adjusted to a nominal concentration of approximately 3000 mg/L by dilution with municipal water. Fifty mL of synthetic sewage (Appendix I of Protocol) was added to each liter of adjusted sludge. The sludge was maintained at a temperature of 20 ¿ 2¿C and continuously aerated overnight. The pH and total suspended solids concentration of the activated sludge were determined on the day of use in the study.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

10 min

Test temperature:

18.5 – 19.9 degree C.

pH:

7.8 on day of testing

Nominal and measured concentrations:

Nominal = 10, 100, 1000 and 1000 (abiotic) mg/L

Details on test conditions:

Control, reference, and treatment test mixtures were incubated at 20 ± 2ºC and aerated for three hours at a rate sufficient to provide aerobic conditions and maintain solids in suspension. The mixtures were prepared and aerated in 1000 mL Erlenmeyer flasks and then transferred to fill 300 mL biochemical oxygen demand (BOD) bottles to conduct dissolved oxygen (DO) measurements. Test mixtures were identified by project number, test substance identification, test concentration, and bottle number.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

10 min

Dose descriptor:

IC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The respiration rates in the two controls were 40.0 and 30.0 mg O2/L/hr. The biotic test mixtures dosed with the Substance at concentrations of 10 and 100 mg/L had measured respiration rates of 38.9 and 37.4 mg O2/L/hr, respectively. The biotic test mixture dosed with the Substance at 1000 mg/L had a mean measured respiration rate of 39.5 mg O2/L/hr. The abiotic treatment mixture dosed with 1000 mg/L of the Substance had a respiration rate of 0.0 mg O2/L/hr showing there was no significant uptake or release of oxygen resulting from abiotic reactions of the test substance

Validity criteria fulfilled:

yes

Conclusions:

An inhibitory dose response effect was not observed for the treatment groups. Therefore, the EC50/NOEC value for the Substance is > 1000 mg/L; the highest concentration tested and limitsconcentration for this study. The abiotic treatment mixture dosed with 1000 mg/L of the substance
had a respiration rate of 0.0 mg O2/L/hr showing there was no significant uptake or release of oxygen resulting from abiotic reactions of the test substance.

Executive summary:

The potential effect of the Substance on activated sludge microorganisms maintained in an aerobic environment was assessed by the Activated Sludge Respiration Inhibition Test Method (OECD Guideline 209). The test contained control, reference and treatment groups. The control replicates were used to determine the background respiration rate of the sludge and were not dosed with the test or reference substance. The reference group was dosed with 3,5-dichlorophenol, a known inhibitor of respiration, at concentrations of 3, 15 and 50 mg/L. The treatment group was dosed with the Substance at concentrations of 10, 100, and 1000 mg/L. Single treatments were tested at concentrations of 10 and 100 mg/L, triplicate treatments were tested at 1000 mg/L. An abiotic control was dosed with the test substance at a concentration of 1000 mg/L to discriminate between abiotic uptake by the test substance and microbial respiration. After an exposure period of three hours, the respiration rates of the test solutions were measured using a YSI Model 50B-115 Dissolved Oxygen Meter.

Both controls had respiration rates above 28.4 mg O2/L/hr, which is the low limit based on the validity criteria for mixtures with 1.42 g dry weight of suspended solids per liter. The coefficient of variation of the two control respiration rates was 20.2%, and was within the 30% limit established for the test. The validity of the test was further supported by the results from the 3,5-dichlorophenol reference group, which resulted in an EC50 value of 19.5 mg/L, with 95 percent confidence limits of 15 mg/L and 50 mg/L. The EC50 for the reference substance was within the 2 to 25 mg/L range considered acceptable for the test.

An inhibitory dose response effect was not observed for the treatment groups. Therefore, the EC50 value for the Substance is > 1000 mg/L; the highest concentration tested and limitsconcentration for this study. The abiotic treatment mixture dosed with 1000 mg/L of the substance had a respiration rate of 0.0 mg O2/L/hr showing there was no significant uptake or release of oxygen resulting from abiotic reactions of the test substance.

Description of key information

An inhibitory dose response effect was not observed for the treatment groups. Therefore, the EC50 value for the Substance is > 1000 mg/L; the highest concentration tested and limitsconcentration for this study. The abiotic treatment mixture dosed with 1000 mg/L of the substance had a respiration rate of 0.0 mg O2/L/hr showing there was no significant uptake or release of oxygen resulting from abiotic reactions of the test substance.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

Activated Sludge Study:

The potential effect of the Substance on activated sludge microorganisms maintained in an aerobic environment was assessed by the Activated Sludge Respiration Inhibition Test Method (OECD Guideline 209). The test contained control, reference and treatment groups. The control replicates were used to determine the background respiration rate of the sludge and were not dosed with the test or reference substance. The reference group was dosed with 3,5-dichlorophenol, a known inhibitor of respiration, at concentrations of 3, 15 and 50 mg/L. The treatment group was dosed with the Substance at concentrations of 10, 100, and 1000 mg/L. Single treatments were tested at concentrations of 10 and 100 mg/L, triplicate treatments were tested at 1000 mg/L. An abiotic control was dosed with the test substance at a concentration of 1000 mg/L to discriminate between abiotic uptake by the test substance and microbial respiration. After an exposure period of three hours, the respiration rates of the test solutions were measured using a YSI Model 50B-115 Dissolved Oxygen Meter.

Both controls had respiration rates above 28.4 mg O2/L/hr, which is the low limit based on the validity criteria for mixtures with 1.42 g dry weight of suspended solids per liter. The coefficient of variation of the two control respiration rates was 20.2%, and was within the 30% limit established for the test. The validity of the test was further supported by the results from the 3,5-dichlorophenol reference group, which resulted in an EC50 value of 19.5 mg/L, with 95 percent confidence limits of 15 mg/L and 50 mg/L. The EC50 for the reference substance was within the 2 to 25 mg/L range considered acceptable for the test.

An inhibitory dose response effect was not observed for the treatment groups. Therefore, the EC50 value for the Substance is > 1000 mg/L; the highest concentration tested and limitsconcentration for this study. The abiotic treatment mixture dosed with 1000 mg/L of the substance had a respiration rate of 0.0 mg O2/L/hr showing there was no significant uptake or release of oxygen resulting from abiotic reactions of the test substance.