1-ethyl-1-methylpyrrolidinium bromide

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:

August-September 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

The Guidelines for the Testing of Chemicals, Effects on Biotic Systems, Version 2, 209 Activated Sludge, Respiration Inhibition Test, China Environmental Press. 2013.

Qualifier:

according to guideline

Guideline:

other: Guidelines of testing of chemicals, effects on biotic systems, version 2, 209 activated sludge, resporation inhibition test, China environmental press, 2013.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

CAS No. 69227-51-6
Molecular formula C7H16NBr
Molecular weight 194.11
Physicochemical property
Appearance Colorless liquid
Storage and protection
Storage condition 10~30 °C
Batch number W5-03
Purity 65.3%
Effective date 2019-08

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

Preparation of test solution
The preparation information of test solution was listed in attached table 1. Test mixtures, reference mixtures and the blank and abiotic controls were incubated at the test temperature under conditions of forced aeration (about 1 L/min) to keep the dissolved oxygen concentration above 60 ~ 70% saturation and to maintain the sludge flocs in suspension

Preparation of 1- methyl group -2- thiourea
2.32 g/L of 1- methyl group -2- thiourea solution: 1.1601 g of 1- methyl group -2- thiourea was dissolved in water and made up to 500 mL.
Preparation of 3,5-Dichlorophenol
500 mg/L of 3,5-Dichlorophenol solution: 0.0501 g of 3,5-Dichlorophenol was dissolved in water and made up to 100 mL.

Test organisms (species):

activated sludge

Details on inoculum:

Information of Inoculum
The fresh activated sludge used in the test was collected from Wuzhong district urban area sewage treatment plant. The address of the plant is No. 1, Baodai East Road, Suzhou city. The batch No. of inoculum was AS-20160817-01.
Justification for selection of inoculum
The activated sludge of waste water treatment plant is recommended by test guideline.
Pre-treatment of inoculum
The activated sludge was washed by dechlorinated tap water after the suspended solids and coarse particles was moved, and then will be centrifuged it at 1100 g for 5 min, and the supernatant will be discard. Repeat the process for 7 times.
Determination of the moisture content of the activated sludge
The dry weight content of the activated sludge was determined in triplicates after pre-treatment, and the average value was 7.57%. 792.6 g of the activated sludge (wet weight) was weighed, and 1L of synthetic sewage was added together, then suspended it with dechlorinated tap water to make it up to 20 litres After that, the suspension was aerated at test temperature until to use.

Test type:

static

Water media type:

freshwater

Remarks:

purified

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

exposure for 3 hr under aeration

Post exposure observation period:

no

Hardness:

no

Test temperature:

20±2 °C. One bottle of water was put into the test zone in order to monitor the temperature, and the water temperature was continuously monitored by a digital thermometer, and the min and max temperature was 19.4°C and 21.9° C.

pH:

6.66-8.16

Dissolved oxygen:

The concentration keep above 60 ~ 70% saturation

Salinity:

no

Conductivity:

no

Nominal and measured concentrations:

1000, 2000, 4000, 8000 and 1600mg/L of test substance (based on effective concentration)

Details on test conditions:

Duration of exposure Exposure for 3h under aeration
Test vessels 1000 mL beakers to contain 500 mL of reaction mixture
Aeration device Through wash bottles containing water to humidify the air and the air flow rate was 1L/min.
Measuring apparatus BOD flask (250 mL)
Temperature 20±2 oC. One bottle of water was put into the test zone in order to monitor the temperature, and the water temperature was continuously monitored by a digital thermometer, and the min and max temperature was 19.4oC and 21.9 oC.

Reference substance (positive control):

yes

Remarks:

3,5 Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

6 171.1 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

ca. 48 903.7 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Details on results:

The blank controls (without the test substance or reference substance) oxygen uptake rate was 23.75 mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour, greater than 20 mg/(h·g SS).
According to the inhibition of oxygen uptake rates , the EC50 on the inhibition of total oxygen consumption for test substance was 6171.1 mg/L, and its associated lower and upper 95% confidence limits was 4030.5-11499.2 mg/L(based on the actual concentration). the EC50 on the inhibition of heterotrophic oxygen uptake for test substance was 48903.7 mg/L, and its associated lower and upper 95% confidence limits was 27706.9~142204.9 mg/L(based on the actual concentration).

Results with reference substance (positive control):

The EC50 of 3,5-DCP for total respiration
The EC50 of 3,5-DCP was 9.66 mg/L in the test, in the range 2 mg/L to 25 mg/L for total respiration, and its associated lower and upper 95% confidence limits was 2.93-30.0 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 on the inhibition of total oxygen consumption for test substance was 6171.1 mg/L ,and the EC50 on the inhibition of heterotrophic oxygen uptake for test substance was 48903.7 mg/L under the current test condition.

Executive summary:

Objective

To evaluate the substances which may adversely affect aerobic microorganism obtained from a sewage treatment plant by measuring the respiration rate under defined conditions in the presence of different concentrations of the test substance.

Method

1000、2000、4000、8000 and 16000 mg/L of test substance(based on the effective concentration) were conducted in the test. The respiration rates of test substance of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. In addition, the sludge activity was determined by 3,5-DCP in the test. At the same time, the respiration rate with or without 1-methyl group-2-thiourea was measured to evaluate the inhibition of heterotrophic oxygen uptake and nitrification for test substance .

Result

The blank controls oxygen uptake rate was 23.75 mg/(h·g SS), and the coefficient of variation of oxygen uptake rate in control replicates was 9.84%,less than 30% at the end of definitive test.

The EC50 of 3,5-DCP was 9.66 mg/L in the test, and in the range 2 mg/L to 25 mg/L for total respiration. The EC50 on the inhibition of total oxygen consumption for test substance was 6171.1 mg/L, and its associated lower and upper 95% confidence limits was 4030.5-11499.2 mg/L(based on the effective concentration). the EC50 on the inhibition of heterotrophic oxygen uptake for test substance was 48903.7 mg/L, and its associated lower and upper 95% confidence limits was 27706.9~142204.9 mg/L(based on the effective concentration).

Description of key information

The EC50 on the inhibition of total oxygen consumption for test substance was 6171.1 mg/L ,and the EC50 on the inhibition of heterotrophic oxygen uptake for test substance was 48903.7 mg/L under the current test condition.

Key value for chemical safety assessment

EC50 for microorganisms:

6 171.1 mg/L