3-(dimethylamino)propylurea

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:

2000

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))

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.6800 (Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Following a preliminary range-finding study, activated sewage sludge was exposed to an aqueous solution of the test material at concentrations of 100, 180, 320, 560 and 1000 mg/l for a period of 3 hours at 21 "C with the addition of a synthetic sewage as a respiratory substrate.

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 26 January 2000 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Belper, Derbyshire, UK which treats predominantly domestic sewage.

Test type:

static

Water media type:

freshwater

Total exposure duration:

3 h

Test temperature:

The activated sewage sludge sample was maintained on continuous aeration in the laboratory at a temperature of 21 °C and was used on the day of collection.

pH:

The pH of the sample was 7.6 and the suspended solids equal to 4.0 g/l prior to use.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

180 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

not determinable

Remarks:

It was not possible to determine an EC50 value after 30 minutes contact time as no concentrationtested resulted in 50% inhibition of respiration rate.

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

820 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The following results were derived:

3-(DIMETHYLAMIN0)PROPYLUREA EC50 (30 minutes): >1000 mgll
3,5-dichlorophenol EC5o(30 minutes): 30 mg/l
Variation in respiration rates of controls 1 and 2 after 30 minutes: * 0%.
* It was not possible to determine an EC50 value after 30 minutes contact time as no concentration tested resulted in 50% inhibition of respiration rate.

3-(DIMETHYLAMIN0)PROPYLUREA EC50(3 hours): 820 mg/l
3,5-dichlorophenol EC50 (3 hours): 16 mg/l
Variation in respiration rates of controls 1 and 2 after 3 hours: +/- 0 %.

The No Observed Effect Concentration (NOEC) after 3 hours was 180 mg/l.

Validity criteria fulfilled:

yes

Conclusions:

The effect of the test material on the respiration of activated sewage sludge gave a 3-Hour EC50 of 820 mg/l. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 180 mg/l.

Executive summary:

A study was performed to assess the effect of the test material on the respiration of activated sewagesludge. The method followed that described in the OECD Guidelines for Testing of Chemicals (1984) No 209 "Activated Sludge, Respiration Inhibition Test", EEC Commission Directive 87/302/EEC and US EPA Draft Ecological Effects Test Guidelines OPPTS 850.6800.

 

Following a preliminary range-finding study, activated sewage sludge was exposed to an aqueous solution of the test material at concentrations of 100, 180, 320, 560 and 1000 mg/l for a period of 3 hours at 21 °C with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 30 minutes and 3 hours contact time and compared to data for the control and a reference material, 3,5 -dichlorophenol.

 

The effect of the test material on the respiration of activated sewage sludge gave a 3 -Hour EC50 of 820 mg/l. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 180 mg/l.

Description of key information

The effect of the test material on the respiration of activated sewage sludge gave a 3-Hour EC50 of 820 mg/l. The No Observed Effect Concentration (NOEC) after 3 hours exposure was 180 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:

820 mg/L

EC10 or NOEC for microorganisms:

180 mg/L