Quaternary ammonium compounds, C12-14-alkyltrimethyl, Me sulfates

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

From 04 April, 2012 to 26 April, 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

KL2 due to RA

Justification for type of information:

Refer to section 13 for details on the read-across justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

C12-14 alkyl ethyl dimethyl ethyl sulphates QAS was added to the incubation vessels using a stock solution of approximately 1.0 g/L.The stock solution of quaternary ammonium compounds, C12-14 (evennumbered)-alkylethyldimethyl, ethyl sulphates was prepared by dissolving 0.78 g C12-14 alkyl ethyl dimethyl ethyl sulphates QAS in 780 mL deionized water.

pH stock solution C12-14 alkyl ethyl dimethyl ethyl sulphates QAS =6.6

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Unadapted secondary activated sludge was obtained (24-04-2012) from the WWTP Nieuwgraaf in Duiven. The WWTP Duiven is an activated sludge plant treating predominantly domestic wastewater. Prior to use the activated sludge was homogenized with a syringe. The dry weight of the homogenized activated sludge was determined and subsequently concentrated by settlement to the required dry weight concentration. The dry weight of the activated sludge in the incubation vessels was 1.5 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

Temperature varied from 19.8 to 20.6°C.

pH:

The pH of the reaction mixtures after the incubation period ranged from 7.2 to 7.4.

Dissolved oxygen:

aerobic during test

Details on test conditions:

-The test was performed in 300 mL Erlenmeyers.
-The homogenized activated sludge was incubated in a shaking water bath (100 rpm, 20°C) for 3 hours with various concentrations of the test
compound and synthetic sewage.
-Synthetic sewage was added to the activated sludge (1.6 mL on a total volume of 50 mL).
Synthetic sewage contained per liter: 16 g peptone
11 g meat extract
3 g urea
0.7 g NaCl
0.3 g CaCl2
0.2 g MgSO4.7H2O
2.8 g K2HPO4
-Different concentrations (spaced by a factor two) of test compound and reference compound where added using stock solutions both of 1.0 g/L
-Tap-water was used to fill up the total test volume to 50 mlL
- The dry weight concentration of the activated sludge in the test was 1.5 g/L.
-The tested concentrations of the reference compound 3,5-dichlorophenol where: 2.5 mg/L, 5.0 mg/L,10.0 mg/L, 20.0 mg/L and 40.0 mg/L
-The tested concentrations of hydrogenated (tallow alkyl) trimethyl ammonium chloride where : 10 mg/L, 20 mg/L, 40 mg/L, 80 mg/L and 160 mg/L.
-Controls without test substance (or reference compound) are measured at the beginning and at the end of the test
-The inhibitory effect of the test substance/reference compound is expressed as a percentage of the mean of the two control respiration rates.
-An abiotic control was not performed because neither reduction of oxygen by the test substance nor formation of oxygen due to chemical
breakdown of the test substance is expected.
-No specific analyses were performed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

9 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

30 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

Test conditions
The pH of the reaction mixtures after the incubation period ranged from 7.2 to 7.4. Temperature varied from 19.8 to 20.6°C. These conditions allow
respiration of the activated sludge used.

Validity of the test
The validity of the test is demonstrated by three criteria. First, the coefficient of variation of the replicates of the control oxygen uptake rates was 10%, which fulfils the maximum prescribed variation of <30%. Secondly, the prescribed average oxygen uptake rate of > 20 mg O2/g dry weight/hour for the control measurements was achieved (30 mg O2/g dry weight/hour). The third criterion was met as shown by the EC50 of the reference compound of 15 mg/L, which is within the prescribed range of 2 to 25 mg/L.

Activated sludge respiration inhibition test
The inhibitory effect of quaternary ammonium compounds, C12-14 (even-numbered)-alkylethyldimethyl, ethyl sulphates at a particular concentration is expressed as a percentage of the two controls. From the results EC values were calculated.
The EC50 of quaternary ammonium compounds, C12- 14 (even-numbered)-alkylethyldimethyl, ethyl sulphates for activated sludge after 3 hours contact time is 30 mg/L with 95% confidence limits of 13 and 72 mg/L. The EC10, EC20 and EC80 are 9, 14 and 66 mg/L, respectively.

Results with reference substance (positive control):

The EC50 of the reference compound was 15 mg/L at a contact time of 3 h, respectively. These EC50 values is within the prescribed range of 2 to 25 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, 3 h EC50 and EC10 values of test substance in sludge after 3 h of contact time was determined to be 30 and 9 mg/L (nominal) respectively.

Executive summary:

A study was conducted to determine the toxicity of the read-across substance C12 -14 ADMA ES to microorganisms in an activated sludge respiration inhibition testaccording to OECD Guideline 209, in compliance with GLP. The test was valid as shown by the EC50 of the reference substance 3,5 -dichlorophenol (tested at 15 mg/L), the coefficient of variation for oxygen uptake rates in control (10%) and the average oxygen uptake rate for the control replicates (30 mg O₂/g dw/h). The toxicity of the test substance to activated sludge was determined for an exposure period of 3 h, using various concentrations of the test substance. The inhibitory effect of the substance at a particular concentration is expressed as a percentage of the two controls. No analytical determination was performed for the test substance. Under the study conditions, 3 h EC50 of the test substance in sludge was determined to be 30 mg/L (95% C.I. 13 - 72 mg/L). The 3 h EC10 was determined to be 9 mg/L (Geerts, 2012).

Key value for chemical safety assessment

EC50 for microorganisms:

30 mg/L

EC10 or NOEC for microorganisms:

9 mg/L

Additional information

A study was conducted to determine the toxicity of the read-across substance C12 -14 ADMA ES to microorganisms in an activated sludge respiration inhibition testaccording to OECD Guideline 209, in compliance with GLP. The test was valid as shown by the EC50 of the reference substance 3,5 -dichlorophenol (tested at 15 mg/L), the coefficient of variation for oxygen uptake rates in control (10%) and the average oxygen uptake rate for the control replicates (30 mg O₂/g dw/h). The toxicity of the test substance to activated sludge was determined for an exposure period of 3 h, using various concentrations of the test substance. The inhibitory effect of the substance at a particular concentration is expressed as a percentage of the two controls. No analytical determination was performed for the test substance. Under the study conditions, 3 h EC50 of the test substance in sludge was determined to be 30 mg/L (95% C.I. 13 - 72 mg/L). The 3 h EC10 was determined to be 9 mg/L (Geerts, 2012).