Formaldehyde, oligomeric reaction products with 4,4'-isopropylidenediphenol and diethylenetriamine

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

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))

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

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 13 May 2016 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK which treats predominantly domestic sewage.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Reference substance (positive control):

yes

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

ca. 18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Validity criteria fulfilled:

yes

Conclusions:

The No Observed Effect Concentration (NOEC) after 3 hours exposure was 18 mg/L.

Executive summary:

Introduction

A study was performed to assess the effect of the test item on the respiration of activated sewage sludge. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2010) No. 209 "Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation)".

Methods

Following a preliminary range-finding and initial experiment, activated sewage sludge was exposed to an aqueous dispersion of the test item at concentrations of 10, 18 and 32 mg/L (5 replicates) for a period of 3 hours at measured temperatures of between 20 and 22 °C with the addition of a synthetic sewage as a respiratory substrate.

The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item, 3,5-dichlorophenol.

Results

The effect of the test item on the respiration of activated sewage sludge gave a No Observed Effect Concentration (NOEC) after 3 hours exposure of 18 mg/L.

The reference item gave a 3-Hour EC50 value of 6.6 mg/L, 95% confidence limits 4.9 to 8.9 mg/L.

Description of key information

The No Observed Effect Concentration (NOEC) after 3 hours exposure was 18 mg/L.