oligomeric reaction product of 2-hydroxybenzaldehyde with 1-chloro-2,3-epoxypropane and phenol

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:

11 February 2016 - 11 February 2016

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

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: EPICLON EXA-7250
Batch/Lot No.: B006
Description: Brown solid (in smaller amount the colour is yellow)
Purity: >99%
Molecular formula: C28H28O6 + (C19H18O4)n
Manufacture date: 02 October 2014
Expiry date: 02 March 2017
Storage condition: Controlled room temperature (15-25oC, below 70 RH%)
Safety precautions: Routine safety precautions (gloves, goggles, face mask, lab coat) for unknown materials were applied to assure personnel health and safety.

Analytical monitoring:

not specified

Test organisms (species):

activated sludge, domestic

Test type:

not specified

Water media type:

other: Deionised water

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

Temperature controlled laboratory
20.5 – 21.1 °C

pH:

Based on this ratio, calculated amounts of wet sludge were suspended in chlorine-free tap water to yield a concentration equivalent to 3 g per litre (on dry weight basis). The pH of the activated sludge inoculum was determined to be pH 7.21. The activated sludge was used directly after conditioning.

Dissolved oxygen:

For the measurement of the respiration rate a well-mixed sample of each treatment was poured into a BOD flask after about 3 hours incubation time, and was not further aerated. The oxygen concentration was measured for about fifteen minutes, with an O2 electrode and was recorded in every half minute. The oxygen consumption (in mg O2 L-1 minute-1) was determined from the most linear part of the respiration curve.

Nominal and measured concentrations:

10, 100, and 1000 mg/L

Details on test conditions:

Aeration: With compressed air (about 2 L/min)
Recording: Test conditions were measured with suitable instruments and documented in the raw data.

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

Results with reference substance (positive control):

The following nominal concentrations of the reference control 3,5-Dichlorophenol were tested on the same activated sludge and under identical conditions as in the case of the test item: 1.0, 3.2, 10.0 and 32.0 mg/L.
In comparison to the controls the inhibition of the respiration rate of the activated sludge was 75.48 % at the highest nominal concentration of 32.0 mg/L.
At the nominal concentrations of 1.0, 3.2 and 10.0 mg/L 18.97 %, 30.85 % and 37.41 % inhibition of the respiration rate was calculated respectively.
The 3-hour EC50 of 3,5-Dichlorophenol was calculated to be 10.79 mg/L with 95% confidence limits of 7.69 – 15.15 mg/L.

TEST ITEM

In comparison to the inoculum controls the inhibition of the respiration rate in the case of the activated sludge was between 0.73 % and 3.20 % in the examined range of 10 – 1000 mg/L of EPICLON EXA-7250 test item.

The average specific respiration rate (RS) of the untreated (Blank) controls (B1-B5) was 26.79 mg O2/L/h/g solid.

The variation coefficient of oxygen uptake rate in above untreated replicates was 2.21 %.

Conclusions:

Under the conditions of this Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation) the observed endpoint for the effect of EPICLON EXA-7250 was the following:
The 3-hour EC50: > 1000 mg/L

Based on the results of this study, the test item EPICLON EXA-7250 had no inhibition effect on the total respiration rate of the microorganisms of the activated sludge, therefore further testing for nitrification inhibition is not necessary.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L