Reaction mass of 1,2,3,4,4a,5,6,7-octahydro-2,5,5-trimethyl-2-naphthol and 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)butan-2-one and 4-(2,6,6-trimethyl-2-cyclohexen-1-yl)butan-2-one

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:

24 & 25 September 2020

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:

yes

Remarks:

This minor deviation was considered not to affect the results of the test as no impact was observed on the blank controls

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

- 6 replicates bottles containing synthetic sewage feed, test water and inoculum (blank controls)
- 5 replicates bottles per test concentration containing synthetic sewage feed, test water, test item and inoculum (test mixtures)
- 1 replicate per reference substance concentration containing synthetic sewage feed, test water, reference substance and inoculum (reference mixtures)

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The activated sludge concentration in all test, reference and blank mixtures was approx. 1.5 g.L-1 of suspended solids.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

At the end of incubation, samples were withdrawn to measure the rate of decrease of dissolved O2 in completely filled all-glass BOD.

Test temperature:

18.5 - 22.3°C

pH:

7.428 - 7.803

Nominal and measured concentrations:

0,10,32,100 mg.L-1

Details on test conditions:

Controlled environment room (20°C ± 2°C)
All suspensions were aerated and stirred during the exposure period.

Reference substance (positive control):

yes

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

LOEC

Effect conc.:

316 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Validity criteria fulfilled:

yes

Conclusions:

Under the experimental conditions, and based upon nominal concentrations, the 3-hour EC50 value was determined to be higher than 1000 mg test item.L-1. The NOEC value was 100 mg test item.L-1 and the LOEC 316 mg.L-1.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

100 mg/L