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Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Endpoint:
activated sludge respiration inhibition testing
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Cross-reference
Reason / purpose:
data waiving: supporting information
Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From February 16, 2016 to March 17, 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Version / remarks:
according to slightly modified OECD, EU and ISO Test Guidelines
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Substance name: PARAD Substance 139
Chemical name (IUPAC): 2-propenoic acid, 2-methyl-, 2-hydroxyethyl ester, reaction products with phosphorus oxide (P2O5)
Batch/lot No.: DR0006631
Reaction products: diphosphorous pentaoxide (26.6 wt %); 2-hydroxyethyl metacrylate (73.2 wt %)
Solubility in water: soluble in water at 1.0 g/L
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
River water was sampled from the Rhine near Heveadorp, The Netherlands (11-02-2016). The nearest plant (Arnhem-Zuid) treating domestic wastewater biologically was 3 km upstream. The river water was aerated for 7 days before use to reduce the endogenous respiration (van Ginkel and Stroo, 1992). River water without particles was used as inoculum. The particles were removed by sedimentation after 1 day while moderately aerating. The inoculum was not pre-exposed to the test substance.
Duration of test (contact time):
28 d
Initial conc.:
4 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
- Test bottles:
The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.
- Nutrients, and stocks:
The river water used in the Closed Bottle test was spiked per liter of water with 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.4 mg Na2HPO4·2H2O, 22.5 mg MgSO4·7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3·6H2O. Ammonium chloride was not added to the river water to prevent nitrification. Sodium acetate and the test substance were added to the bottles using aqueous stock solutions of 1.0 g/L.
- Test procedures
The Closed Bottle test (OECD TG 301) was performed according to the study plan. The study plan was developed from ISO Test Guidelines (1994). Use was made of 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with test substance. The concentrations of the test substance, and sodium acetate in the bottles were 4.0, and 6.7 mg/L, respectively. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. The zero time bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28.
- Analyses
The dissolved oxygen concentrations were determined electrochemically using an oxygen electrode (WTW TrioXmatic EO 200) and meter (WTW OXI 530) (Retsch, Ochten, The Netherlands). The pH was measured using a Eutech Cyberscan pH11 pH meter (Eutech Instruments, Nijkerk, The Netherlands). The temperature was measured and recorded with a sensor connected to a data logger.
Reference substance:
acetic acid, sodium salt
Remarks:
Purity: >99%
Key result
Parameter:
% degradation (O2 consumption)
Value:
71
Sampling time:
28 d
Details on results:
- Theoretical oxygen demand (ThOD)
The calculated theoretical oxygen demand (ThOD) of the test substance was 1.26 mg/mg. The ThOD of the test substance was calculated with the two reactants used to synthesize the test substance. The ThOD of the reactants was identical to the ThOD of the two reactants because all components formed remained in the reactor during the production.
- Toxicity:
Inhibition of the degradation of a well-degradable compound, e.g. sodium acetate by the test substance in the Closed Bottle test was not determined because possible toxicity of the substance to microorganisms degrading acetate was not relevant. Inhibition of the endogenous respiration of the inoculum by the test substance at day 7 was not detected. Therefore, no inhibition of the biodegradation due to the "high" initial test substance concentration was expected.
- Test conditions:
The pH of the media was 8.0 at the start of the test. The pH of the medium at day 28 was 8.0 (control and test). Temperatures were within the prescribed temperature range of 22 to 24°C.
- Validity of the test:
The validity of the test was demonstrated by an endogenous respiration of 1.3 mg/L at day 28. Furthermore, the differences of the replicate values at day 28 were less than 20%. The biodegradation percentage of the reference compound, sodium acetate, at day 14 was 88. Finally, the validity of the test was shown by oxygen concentrations >0.5 mg/L in all bottles during the test period.
- Biodegradability:
The test substance was biodegraded by 71% at day 28 in the Closed Bottle test. The time window was not used as a pass/fail criterion because the test substance consists of many components (UVCB). The test substance should therefore be classified as readily biodegradable.
Key result
Parameter:
ThOD
Value:
1.26 other: mg O2/mg
Results with reference substance:
The ThOD of sodium acetate was 0.78 mg O2/mg.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Under the study conditions, the test substance can be considered readily biodegradable.
Executive summary:

A study was conducted to determine the biodegradation in water of the test substance, according to OECD guideline 301D (Closed Bottle test), in compliance with GLP. The test was performed in 0.30L BOD (biological oxygen demand) bottles with glass stoppers. There were 10 bottles containing only river water, 6 bottles containing river water and sodium acetate, 10 bottles containing river water with the test substance. The concentrations of the test substance, and sodium acetate in the bottles were 4.0, and 6.7 mg/L, respectively. No reduction in the endogenous respiration was observed at Day 7. The test substance was therefore considered to be non-inhibitory to the inoculum. The test substance was biodegraded by 71% at day 28 in the Closed Bottle test. The test was valid, as shown by an endogenous respiration of 1.3 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 88% of its theoretical oxygen demand after 14 d. Oxygen concentrations remained >0.5 mg/L in all bottles during the test period.

Under the study conditions, the test substance can be considered readily biodegradable (van Ginkel, 2016).

Data source

Materials and methods

Results and discussion

Applicant's summary and conclusion