3-(p-methoxyphenyl)-2-methylpropionaldehyde

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:

5 Feb 2013 to 8 March 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Qualifier:

according to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used. The sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until used on the same day.

Duration of test (contact time):

30 d

Initial conc.:

30.1 mg/L

Based on:

test mat.

Remarks:

replicate 1

Initial conc.:

29.9 mg/L

Based on:

test mat.

Remarks:

replicate 2

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

as a percentage of ThOD

Details on study design:

COMPOSITION OF TEST MEDIUM
- Solution A: KH2PO4: 8.5 g; K2HPO4: 21.75 g; Na2HPO4·2H2O: 33.4 g; NH4Cl: 0.50 g, dissolved in water and made up to 1 litre.
- Solution B: CaCl2: 27.5 g, dissolved in water and made up to 1 litre.
- Solution C: MgSO4·7H2O : 22.5 g, dissolved in water and made up to 1 litre
- Solution D: FeCl3·6H2O : 0.25 g; HCl Conc. one drop, dissolved in water and made up to 1 litre
- Preparation: Prepared by mixing 50 ml of solution A and 2000 ml deionised water, adding 5 m of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.

TEST CONDITIONS
- Test temperature: 22.0 - 22.5°C
- Dry weight of suspended solids: Dry weight of suspended solids was 6.00 g/L, diluted to 1.53 g/L. To obtain a concentration of 30 mg/L (dry weight) in 103 ml total volumes (Flasks 17 and 18), 2.00 ml of sludge was added (inoculum). To obtain a concentration of 30 mg/L (dry weight) in 255 ml total volumes (Flasks 1, 2, 5 and 6), 5.00 ml of sludge was added (inoculum).

TEST SYSTEM
- Apparatus: The respirometer used during this study is an Oxitop Control System, made by Wissenschaftlich-Technische Werkstätten (WTW), Weilheim, Germany.
- Number of culture flasks/concentration: 2
- Preparation of the flasks: Test substance samples (7.65 mg, corresponding to 30 mg/L in 255 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop whereas the reference substance (sodium benzoate) is added as 1.00 ml of a 10.2 g/L solution in mineral medium, to give a total volume of 103 ml. Flasks are filled with 250 ml of mineral medium (flasks containing reference substance: 100 ml). Samples of test or reference substance are added. Then suspended sludge diluted to a concentration of 1.53 g/L dry matter is added. Except when the test substance has an acid or alkaline character, the pH of each flask is not measured but assumed to be the same as the mineral medium, in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. Neutral test substances, even sodium benzoate, were shown not to affect the pH of the medium by more than 0.1 pH unit. Two sodium hydroxide pellets are placed in the quivers on top of the bottle, and the flasks are closed tightly with the measuring heads. The flasks are allowed to equilibrate to the test temperature. The measurement is started by programming the measuring unit of the Oxitop test flasks, and the test flasks are placed in the temperature controlled cupboard of the Oxitop system. After temperature equilibration, the controller of the instrument starts the data acquisition (time zero of the experiment).

SAMPLING
- Oxygen consumption: Every day the oxygen consumption of each flask is recorded
- pH: At the beginning and at the end of the test period.
- Other: the temperature and stirring were checked daily.

Reference substance:

benzoic acid, sodium salt

Test performance:

VALIDITY
- Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days: the activity of the inoculum was thus verified (validity criterion).
- The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled for the flasks containing test substance.
Therefore, the test is considered valid.

Key result

Parameter:

% degradation (O2 consumption)

Value:

81

Sampling time:

28 d

Details on results:

The pass-level (of 10% degradation) was reached after 6 days, and increased up to 81% after 28 days in a dose-dependent manner (see 'Any other information on results incl. tables'). The 10-day window criterion is also fulfilled (10% biodegradation on day 6 and 70% on day 16).

Results with reference substance:

Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days.

Table: O2 uptake, biodegradation of test substance (mg O2/L, adjusted to nominal concentrations)

	Days		5	6	14	16	21	28	30
O2 uptake of sludge (inoculum blank)	1	B1	21.5	24.2	31.0	32.3	35.0	37.7	37.7
	2	B2	20.2	22.9	29.6	31.0	35.0	37.7	37.7
	mean	B	20.9	23.6	30.3	31.7	35.0	37.7	37.7
O2 uptake of test subst. + sludge	5	C1	28.3	32.3	76.5	80.6	90.0	94.0	95.4
	6	C2	26.9	29.6	75.5	84.9	93.1	98.5	99.8
O2 uptake of test substance		C1-B	7.4	8.7	46.2	49.0	55.0	56.3	57.7
		C2-B	6.1	6.1	45.2	53.3	58.1	60.8	62.1
% biodegradation of test substance		D1	10	12	64	67	76	78	79
		D2	8	8	62	73	80	84	85
	mean	D	9	10	63	70	78	81	82

Calculations:

B1, B2, C1, C2: experimental O2 uptake values

B = (B1 + B2) / 2

D1 = 100 * (C1 – B) / ThoD * [S]

D2 = 100 * (C2 – B) / ThoD * [S]

D = (D1 + D2)/2

[S]: Initial test substance concentration (mg/L)

ThOD test substance = 2.42 mg O2/mg

 

Table: Reference substance Sodium Benzoate; O2 uptake (mg O2/L, adjusted to nominal concentrations)

	Days		5	7	14	21	28
O2 uptake of sludge (inoculum blank)	1	B1	21.5	24.2	31.0	35.0	37.7
	2	B2	20.2	22.9	29.6	35.0	37.7
	mean	B	20.9	23.6	30.3	35.0	37.7
O2 uptake of ref. subst. + sludge	17	A1	131.1	146.2	172.4	188.5	198.6
	18	A2	131.1	141.1	167.3	183.4	193.5
O2 uptake of ref. substance		A1-B	110.2	122.6	142.1	153.5	160.9
		A2-B	110.2	117.6	137.0	148.4	155.8
% biodegradation of reference substance		D1	66	74	85	92	97
		D2	66	71	82	89	94
	mean	D	66	72	84	91	95

Calculations:

B1, B2, A1, A2: experimental O2 uptake values

B = (B1 + B2) / 2

D1 = 100 * (A1 – B) / ThoD * [S]

D2 = 100 * (A2 – B) / ThoD * [S]

D = (D1 + D2)/2

[S]: Initial reference substance concentration (mg/L)

ThOD reference substance = 1.67 mg O2/mg

Validity criteria fulfilled:

yes

Remarks:

see 'Test performance'.

Interpretation of results:

readily biodegradable

Conclusions:

The substance is biodegraded by 81% at day 28 in the OECD TG 301F Manometric Respirometry Test and the 10-day time window criterion was met. Therefore, the substance should be classified as readily biodegradable.

Executive summary:

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F (Manometric Respirometry) and in compliance with GLP criteria. In this study 30 mg/L test substance was inoculated with activated sludge from a municipal wastewater treatment plant for 30 days under aerobic conditions in the dark. During the incubation period the biological oxygen demand (BOD) was measured and biodegradation expressed as percentage of the theoretical uptake (ThOD). After the 28-day incubation period 81% of the substance was biodegraded. The 10-day window criterion was met. Based on these findings, the test substance is classified as readily biodegradable.

Description of key information

The biodegradation potential of the substance in water was determined in a screening study according to OECD TG 301F (Manometric Respirometry) and in compliance with GLP criteria. In this study 30 mg/L test substance was inoculated with activated sludge from a municipal wastewater treatment plant for 30 days under aerobic conditions in the dark. During the incubation period the biological oxygen demand (BOD) was measured and biodegradation expressed as percentage of the theoretical uptake (ThOD). After the 28-day incubation period 81% of the substance was biodegraded. The 10-day window criterion was met. Based on these findings, the test substance is classified as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable