L-97-034-PB

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11th February - 3rd March 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Pentaerythritol mixed esters with 2-methyl butyric acid, n-pentanoic acid, n-heptanoic acid, 3,5,5-trimethylhexanoic acid, n-octanoic acid, n-decanoic acid

Cas Number:

141686-49-9

IUPAC Name:

Pentaerythritol mixed esters with 2-methyl butyric acid, n-pentanoic acid, n-heptanoic acid, 3,5,5-trimethylhexanoic acid, n-octanoic acid, n-decanoic acid

Constituent 2

Reference substance name:

Trimethylol propane mixed esters with 2-methyl butyric acid, n-pentanoic acid, n-heptanoic acid, 3,5,5-trimethylhexanoic acid, n-octanoic acid, n-decanoic acid

Cas Number:

141686-50-2

IUPAC Name:

Trimethylol propane mixed esters with 2-methyl butyric acid, n-pentanoic acid, n-heptanoic acid, 3,5,5-trimethylhexanoic acid, n-octanoic acid, n-decanoic acid

Test material form:

liquid

Details on test material:

Identification: Hatcol ® 1772
Appearance/physical state: Clear colorless liquid
Purity: 100% (no solvent present)
Composition: 70% pentaerythritol esters described by CAS# 141686-49-9; 30% trimethylolpropane esters described by CAS# 141686-50-2

Sampling and analysis

Analytical monitoring:

no

Test solutions

Details on test solutions:

In the range-finding test, activated sewage sludge micro-organisms were exposed to a series of nominal test concentrations of 100 and 1000 mg/L. The test item was dispersed directly in water.

To prepare the test series amounts of the test material (50 and 500 mg) were each separately dispersed in water (approximately 250 ml) with the aid of ultrasonication for a period of 30 minutes. Synthetic sewage (16 ml), activated sewage sludge (200 ml) and water, to a final volume of 500 ml, were added to each giving the test concentrations of 100 and 1000 mg/L.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The activated sewage sludge sample was maintained on continuous aeration in the laboratory at a temperature of approximately 21ºC and was used on the day of collection. The pH of the sample was 7.3 and the suspended solids equal to 4.0 g/L prior to use.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test conditions

Hardness:

Approximately 100 mg/L at CaCO3

Test temperature:

21ºC

pH:

7.3

Nominal and measured concentrations:

1000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 16 mL of synthetic sewage diluted to 300 mL with water and 250 mL of inoculum in 500 mL conical flask
- Aeration: aerated with compressed air
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Laboratory tap water dechlorinated by passage through an activated carbon filter with a total hardness of approximately 100 mg/L as CaCO3.

OTHER TEST CONDITIONS
- Light intensity: Normal laboratory lighting

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
Rate of respiration was measured after 3 hours using a Yellow Springs dissolved oxygen meter fitted with a Biological Oxygen Demand (BOD) probe. The rate of respiration for each flask was measured over the linear portion of the oxygen consumption trace (between approximately 8.3 mg O2/L and 0.5 mg O2/L).

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 100 and 1000 mg/L
- Results used to determine conditions for the definitive study: No significant effect on respiration was observed at either of the test concentrations employed.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The No Observed Effect Concentration (NOEC) after 3 h was ≥1000 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The No Observed Effect Concentration (NOEC) after 3 h was ≥1000 mg/L.

Executive summary:

Introduction

A study was performed to assess the effect of the test material on the respiration of activated sewage sludge. The method followed that described in the OECD Guidelines for Testing of Chemicals (1984) No. 209 'Activated Sludge Respiration Inhibition Test' and EEC Commission Directive 87/302/EEC.

Procedure

The test material was aerated for a period of 3 hours at 21ºC in the presence of activated sewage sludge 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.

Results

The effect of the test material on the respiration of activated sewage sludge gave a 3 -hour EC₅₀ of greater than 1000 mg/L. Correspondingly, the No Observed Effect Concentration (NOEC) was greater than or equal to 1000 mg/L.