2-sec-butylphenol

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10-jul-2009 to 31-aug-2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: • ISO Standard 10707, Water Quality - Evaluation in an aqueous medium of the "ultimate” aerobic biodegradability of organic compounds - Method by analysis of biochemical oxygen demand (closed bottle test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

other: The source of test organisms was secondary effluent freshly obtained from a municipal sewage treatment plant

Details on inoculum:

Source
- The source of test organisms was secondary effluent freshly obtained from a municipal sewage treatment plant: 'Waterschap de Maaskant', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.

Treatment
- Secondary effluent was filtered through a coarse filter paper, the first 200 ml was discarded. The filtrate was kept aerated until inoculation.

Inoculation
- 4 ml filtrate of secondary effluent per litre of final volume.

Duration of test (contact time):

28 d

Initial conc.:

1.5 mg/L

Based on:

test mat.

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
1 litre mineral medium contains: 1 ml of solution (A) to (D) and Milli-RO water
Stock solutions of mineral components
A) 8.50 g KH2PO4; 21.75 g K2HPO4; 67.20 g Na2HPO4.12H2O; 0.50 g NH4Cl; dissolved in Milli-Q water and made up to 1 litre, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H2O dissolved in Milli-Q water and made up to 1 litre.
C) 36.40 g CaCl2.2H2O dissolved in Milli-Q water and made up to 1 litre.
D) 0.25 g FeCl3.6H2O dissolved in Milli-Q water and made up to 1 litre.
- Test temperature: between 21.8 and 22.6°C
- pH: At the start of the test: 7.5 to 7.6
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 250-300 ml BOD bottles with glass stoppers
- Number of culture flasks/concentration: 2 flasks per measuring point
- Measuring equipment: Oxygen meter, WTW inolab Oxi 730 supplied with a WTW CellOx 325 oxygen electrode, electrolyte type ELY/G
- Test performed in open system: no

SAMPLING
- Sampling frequency: In duplicate; immediately at the start of the experiment (day 0), and on day 7, 14, 21 and 28
- Sampling method: Whole flask was used for measurement

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Procedure control: reference substance
- Toxicity control: yes, test substance at the lowest concentration, reference substance and inoculum

Reference substance:

other: sodium acetate

Parameter:

% degradation (O2 consumption)

Value:

63

Sampling time:

28 d

Details on results:

The ThOD of 2-sec-butylphenol was calculated to be 2.77 mg O2/mg

Results with reference substance:

The ThOD of sodium acetate (reference substance) was calculated to be 0.78 mg O2/mg.
The reference substance was degraded by at least 60% (84%) within 14 days

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

2-sec-butylphenol was readily biodegradable under the conditions of the closed bottle test presently performed.

Executive summary:

The ready biodegradability of the test substance 2 -sec-butylphenol was evaluated. The method used followed that described in the OECD Guideline No. 301 D, 1992. In addition, the procedures were designed to meet the test methods of the Comission regulation (EC) No 440/2008 of 30 May 2008, Part C.4 -E and the ISO International Standard 10707, 1994.

2 -sec-butylphenol was a clear colourless liquid with a purity of 99.6% and completely soluble at the concentrations tested. Nominal concentrations of 1.5 and 3 mg/l were etsted. The Theoretical oxygen demand of 2 -sec-butylphenol was calculated to be 2.77 mg O2/mg.

The following test setup was applied:

- Inoculum blank (only inoculum, no test substance, duplicate measurements);

- Procedure control (sodium acetate and inoculum, duplicate measurements);

- Test suspension (2 -sec-buytlphenola and inoculum, duplicate measurements);

- Toxicity control (sodium acetate, 2 -sec-butylphenol and inoculum, duplicate measurements).

Preparation of the test media started with a stock solution of 100 mg/l. Thorough mixing was used to accelerate dissolution of the test substance in mineral medium. Exact volumes of the stock solution corresponding to the test concentrations and microbial organisms were added to the test medium. Determination of oxygen concentrations was performed at the start of the experiment (day 0) and on day 7, 14, 21 and 28.

The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed 63% biodegradation of 2 -sec-butylphenol at both concentrations (mean values on day 28). Furthermore, biodegradation of at least 60% was reached within 10 days of biodegradation exceeding 10%. The toxicity control showed that 2 -sec-butylphenol did not inhibit microbial activity.

Since all criteria for acceptability of the test were met, this study was considered as valid.

In conclusion, 2 -sec-butylphenol is designated as readily biodegradable.

Description of key information

2-sec-butylphenol was readily biodegradable under the conditions of the closed bottle test presently performed.
% of degradation of test substance: 63% O2 consumption in 28 d.
The ThOD of 2-sec-butylphenol was calculated to be 2.77 mg O2/mg

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable