2-Propenoic acid, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl ester

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:

10 OCTOBER 2018 - 10 OCTOBER 2018

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))

Version / remarks:

OECD No. 209 Commission Regulation (EC) No 2016/266, C.11

Deviations:

yes

Remarks:

The start value of oxygen content for measurement of oxygen consumption was lower than 7 mg/L. TS3: 6.6 mg/L. An influence to the results of this study can be excluded.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

- Activated sludge suspension from the aeration tank of the wastewater treatment plant of Mannheim, Germany was sieved in the test facility. The suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed once with drinking water and the suspension was adjusted to 3 g/L Dw.
An aliquot of this suspension was added to the test vessels to obtain a sludge concentration of 1.5 g/L dry substance.

Test Concentrations: 1000, 500, 250, 125, 62.5 mg/L as nominal concentration
based on test substance without correction of purity and blank controls.
100, 10, 1 mg/L as nominal concentration based on reference substance (positive control).

Test replicates: 6 replicates for the control,
3 replicates for each test substance concentration,
2 replicates for each reference substance concentration.

Vehicle:

no

Details on test solutions:

1000.4 mg of the reference substance was added to about 800 mL of deionized water and stirred at room temperature until the reference substance was completely dissolved.

The pHvalue of the stock solution was measured and adjusted to 7.4 with 1 M sodium hydroxide solution.

Following this the stock solution was made up to 1L with deionized water. The stock solution appeared yellowish and no undissolved reference substance was visible.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Reason for the selection of the test system: required by the test guidelines
Age: 1 day
Origin: aeration tank of the wastewater treatment plant of Mannheim, Germany
Collection of the test system: 09 Oct 2018
Arrival in the test facility: 09 Oct 2018
After arrival of the activated sludge suspension in the test facility the suspension was sieved
with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over
night at room temperature. At the next day the sludge suspension was washed once with
drinking water and the suspension was adjusted to 3 g/L Dw.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

18.9-19.6 °C

pH:

7.3 - 8.3

Nominal and measured concentrations:

1000, 500, 250, 125, 62.5 mg/L as nominal concentration
based on test substance without correction of purity and blank
controls.

100, 10, 1 mg/L as nominal concentration based on reference
substance.

Details on test conditions:

Incubation time: 3 hours
Test temperature: 18.9 – 19.6 °C
Test vessels: Glas-beakers (nominal volume 1L)
Test volume: 500 mL
Synthetic medium: 16 mL/test vessel of 100-fold concentrated OECD medium
Oxygen concentration during aeration: > 2 mg/L
Oxygen concentration immediately before measurement: > 7 mg/L with the exceptions described in remark test guideline deviations
Duration of the measurement of oxygen consumption: About 8 - 10 min
Sludge concentration in the test vessel: 1.5 g/L Dw

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

720 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Confidence Limits (95%): Lower: 579.9, upper: 955.8

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

190 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Confidence Limits (95%): Lower: 92.1, upper 268.4

Details on results:

Please see Table 4.

Results with reference substance (positive control):

The EC50 of 3,5-dichlorophenol was 5.1 mg/L.
- Results with reference substance valid? Yes

Reported statistics and error estimates:

The consumption rates were used for the determination of the ECx by the probit method based on Finney [1971] with the software TOXRAT Professional 2.10 [2001-2010]. The effect concentrations were given with an accuracy of 2 significant digits.

Table 4: Effect concentrations of the test item.

Toxicity Response Variable	Based on nominal effect concentration [mg/L]	Confidence Limits (95%) lower/upper
EC10	190	92.1/268.4
EC20	300	186.3/385.7
EC50	720	579.3/955.8
EC80	> 1000	----

The value of effect concentrations of EC10 EC20 EC50 were given with an accuracy of 2 significant digits. The degree of inhibition was evaluated by Probit analysis according to Finney.

 

Validity criteria fulfilled:

yes

Remarks:

The coefficient of variation of the six replicates of blank control was 3.9 % O2 consumption. The EC50 of 3,5-dichlorophenol was 5.1 mg/L The mean oxygen uptake of the blank controls was 22 mg/g*h The test conformed to all validity criteria and is valid.

Conclusions:

EC10 = 190 mg/L, EC20 = 300 mg/L, EC50 = 720 mg/L, EC80 = > 1000 mg/L were found in the activated sludge respiration inhibition test with 3 hour residence time for the test substance. All validity criteria were met.

Description of key information

In a 3-hr acute toxicity study sewage sludge according to OECD 209,
microorganisms were exposed to the test item at nominal concentrations
of 0, 62.5, 125, 250, 500 and 1000 mg/L. 
The EC 50 value based on respiration rate after was 720 mg/L 
(95 % confidence limits 579.3 - 955.8 mg/L) after a 3 h contact time.
The EC 10 was determined as 190 mg/L (95 % confidence limits 92.1 - 268.4 mg/L). 
This toxicity study is classified as acceptable and satisfies the guideline requirements for OECD 209 toxicity 
study. All validity criteria were met.

Key value for chemical safety assessment

EC50 for microorganisms:

720 mg/L

EC10 or NOEC for microorganisms:

190 mg/L