Poly(oxy-1,2-ethanediyl), α-[2-(dide- cylmethylammonio)ethyl]- .omega.- hydroxy-, propanoate (salt) (Bardap 26)

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:

15-03-2001 to 02-04-2001

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Directive 87/302/EEC, Part C

Deviations:

no

Principles of method if other than guideline:

Not applicable.

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No information provided.

Analytical monitoring:

no

Details on sampling:

The test material was dissolved directly in water. An amount of test material (500 mg) was dissolved in water with the aid of ultrasonic disruption for approximately 5 minutes and the volume adjusted to 1000 mL to give a 500 mg/L stock solution. Aliquots (1.0, 3.2, 10, 32 and 100 mL) of this stock solution were each separately dispersed with synthetic sewage (16 mL), activated sewage sludge (200 mL) and water, to a final volume of 500 mL, to give the required concentrations of 1.0, 3.2, 10, 32 and 100 mg/L.

Vehicle:

no

Details on test solutions:

At time zero, 16 ml of synthetic sewage was diluted to 300 ml with water and 200 ml of inoculum added in a 500 ml conical flask (first control). The mixture was aerated and the procedure repeated at 15 minute intervals with appropriate amounts of the reference material. The test material vessels were prepared with the aid of ultrasonic disruption. Finally a second control was prepared.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A mixed population of activated sewage sludge micro-organisms was obtained on 02/04/2001 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Belper, Derbyshire, UK.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

Observations were conducted up to 3 hours following the start of exposure.

Hardness:

Approximately 100 mg/l CaCO3

Test temperature:

21°C

pH:

7.7-8.1

Dissolved oxygen:

In some instances the initial and final dissolved oxygen was below those recommended in the test guidelines (6.5 mg O2/l and 2.5 mg O2/l respectively). This was considered to have had no adverse effect on the results of the study given that in all cases the oxygen consumption rate was determined over the linear portion of the oxygen consumption trace.

Salinity:

Not applicable.

Nominal and measured concentrations:

Nominal concentrations Range-finding study: 1.0, 10, 100, 1000 mg/L; Control 3,5-dichlorophenol 3.2, 32 mg/L
Nominal concentrations Definitive study: 1.0, 3.2, 10, 32, 100 mg/L; Control 3,5-dichlorophenol 3.2, 10, 32 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Conical flask

TEST MEDIUM / WATER PARAMETERS
- The test material was dissolved directly in water.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Inhibition on respiration rate

TEST CONCENTRATIONS
- Test concentrations: 1.0, 3.2, 10, 32, 100 mg/L

The study was conducted under normal laboratory lighting in a temperature controlled room at 21°C.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

44 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

24 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The validation criteria for the control respirations rates and reference material EC50 values have been satisfied. Observations made on the test material preparations throughout the study, showed that at all test concentrations employed, no undissolved test material was visible. This is due to the test material being in solution prior to the addition to the test vessel.

Results with reference substance (positive control):

3,5-dichlorophenol, 30 min EC50 was 9.0 mg/L, Variation in respiration rates of controls 1 and 2 after 30 minutes:+/- 3%
3,5-dichlorophenol, 3 hours EC50 was 5.1 mg/L, Variation in respiration rates of controls 1 and 2 after 3 hours:+/- 5%

Reported statistics and error estimates:

No information provided.

Table 1. Bardap 26: Assessment of the Inhibitory Effect on the Respiration of Activated Sludge after 3-hour contact time

 

Nominal Concentration (mg/L)	Measurement Period (min)	O2Consumption Rates (mg O2/L/min)	% Inhibition
Control R1 R2	10	0.45	-
	10	0.50	-
Bardap 26 a. s.   1.0 3.2 10 32 100	10	0.49	[3]
	10	0.46	3
	10	0.44	7
	10	0.15	68
	10	0.01	98
3,5-dichlorophenol     3.2 10 32	10	0.33	31
	10	0.12	75
	10	0.08	83

 

R1-R2 = replicates 1 and 2

[Increase in respiration rate as compared to controls]

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test material on the respiration of activated sewage sludge micro-organisms gave a 3-hour EC50 of 24 mg/L. The No-Observed-Effect-Concentration (NOEC) after 3 hours exposure was found to be 3.2 mg/L.

Executive summary:

The key study was performed in year 2001 according to Directive 87/302/EEC and OECD Guideline 209 and GLP standards. In a study conducted to determine the effect of Bardap 26 (N,N-Didecyl-N-methylpoly(oxyethyl)ammonium Propionate) on microorganisms, activated sludge of a synthetic sewage (as a respiratory substrate) was exposed to the test material for 3 hours at concentrations of 1.0, 3.2, 10, 32, 100 mg/L. The test parameter examined was inhibition on respiration rate.

The control group was maintained under identical conditions as treatment groups but not exposed to the test material.

No inhibition on respiration was observed in the control group during 3 hours contact time. The effect of the test material on the respiration of activated sewage sludge microorganisms gave a 3-hour EC₅₀ of 24 mg/L. The no-observed-effect-concentration (NOEC) after 3 hours exposure was found to be 3.2 mg/L.

Description of key information

One key study and one supporting study are available to assess the toxicity to microorganisms.

The key study was conducted in accordance with OECD Guideline 209 and Directive 87/302/EEC, part C and GLP compliant.

The test organism was exposed to the test material for 3 hours. The no-observed-effect-concentration (NOEC) was found

to be 3.2 mg/L when inhibition on respiration rate was examined, with the EC50 determined to be 24 mg/L. In a supporting

study which is not GLP compliant and poor documented the test material was exposed for 3 hours. The effect of the test

material on the respiration of activated sludge micro-organisms gave a 3-hour EC50 of 16.8 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

24 mg/L

EC10 or NOEC for microorganisms:

3.2 mg/L

Additional information

Key study:

In a study conducted to determine the effects of N,N-Didecyl-N-methylpoly(oxyethyl)ammonium Propionate on activated sewage sludge, the no-observed-effect-concentration (NOEC) was found to be 3.2 mg/L when inhibition on respiration rate was examined, with the EC₅₀ determined to be 24 mg/L. The study was conducted according to the OECD Guideline No. 209 and the Directive 87/302/EEC, part C, using activated sewage sludge as the test system for a period of 3 hours at 21°C with the addition of a synthetic sewage as a respiratory substrate.

The control group was maintained under identical conditions as treatment groups but not exposed to the test material.

 

Supporting study:

In a study conducted to determine the effect of Bardap 26 (N,N-Didecyl-N-methylpoly(oxyethyl)ammonium Propionate on microorganisms, activated sludge was exposed to the test material for 3 hours. The effect of the test material on the respiration of activated sludge micro-organisms gave a 3-hour EC₅₀ of 16.8 mg/L.