AERO 5100 PROMOTER

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:

09 Jun - 17 Jul 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Samples from secondary effluent; Thomdon Sewage Treatment Works, a trickling-filter plant treating predominantly domestic waste
- Storage length: collected on day of test
- Preparation of inoculum for exposure: Maintained under aerobic conditions in the laboratory, then, immediately before use, vacuum-filtered through a Whatman's GFC filter paper and the filtrate used as the inoculum for the test (1 mL/L test medium)

Duration of test (contact time):

28 d

Initial conc.:

5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: The dilution water used to prepare stock and test solutions of mineral salts was tap water that had been softened and treated by reverse osmosis and then purified (resistivity > 18 megohm/cm).
The medium was prepared by adding 1 mL of each of the following stock solutions to each liter of ultrapure water:
Stock 1 (g/L):
Potassium dihydrogen phosphate: 8.50
di-Potassium hydrogen phosphate: 21.75
di-Sodium monohydrogen phosphate dihydrate: 33.40
Ammonium chloride: 0.50
Stock 2 (g/L):
Magnesium sulphate heptahydrate: 22.50
Stock 3 (g/L):
Calcium chloride dihydrate: 36.40
Stock 4 (g/L):
Iron (III) chloride hexahydrate: 0.25
- Test temperature: see "any other information on material and methods incl. tables" below
- pH: see "any other information on material and methods incl. tables" below
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: BOD bottles (277 mL)
- Number of culture flasks/concentration: 3 groups of 18 bottles (one further group with 4 bottles for inhibition assay)
- Measuring equipment: YSI dissolved oxygen meter fitted with a self-stirring DO/temperature bottle probe
- Test performed in closed vessels due to significant volatility of test substance: yes
- Measurements: The concentrations of dissolved oxygen (DO) and the temperatures of the contents of duplicate vessels from each group were measured at the start of the test and after incubation for five days (inhibition test) and also after 7, 11, 14, 18, 21, 25 and 28 days (definitive test) at 22 ± 2 °C. The pH of each control, test and reference mixture was measured after oxygen and temperature measurement.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes
- Other: Reference substance: yes

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

1

Sampling time:

28 d

Details on results:

ThOD values:
2.22 mg O2/mg (test item)
1.67 mg O2/mg (sodium benzoate)

Table 1: Oxygen consumption in test and control bottles

	Mean oxygen concentration and consumption [mg O2/L]
Group	Day 0	Day 5	Day 7	Day 11	Day 14	Day 18	Day 21	Day 25	Day 28
Inoculated mineral salts	8.78	8.82	8.83	8.93	8.84	8.51	8.36	8.73	8.77
	-	[0]	[0]	(0]	[0]	[0.27]	[0.42]	[0.05]	[0.01]
Sodium benzoate (5 mg/L)	8.71	3.97	3.18	2.55	2.30	2.02	2.03	2.33	1.96
	-	[4.74]	[5.53]	[6.16]	[6.41]	[6.42]	[6.26]	[6.33]	[6.74]
AERO® 5100 Promoter (5 mg/L)	8.86	8.69	9.02	8.98	8.78	8.70	8.40	8.70	8.77
	-	[0.17]	[0]	[0]	[0.08]	[0]	[0.04]	[0.11]	[0.08]
Inhibition assay: AERO® 5100 Promoter (5 mg/L) + sodium benzoate (5 mg/L)	8.86	3.60	-	-	-	-	-	-	-
		[5.06]	-	-	-	-	-	-	-

Table 2: BOD (mg O2/mg) and percentage degradation [%]

	BOD [mg O2/mg] and percentage degradation [ ]
Group	Day 5	Day 7	Day 11	Day 14	Day 18	Day 21	Day 25	Day 28
Sodium benzoate (5 mg/L)	0.95	1.11	1.23	1.28	1.28	1.25	1.27	1.35
	[57]	[66]	[74]	[77]	[77]	[75]	[76]	[81]
AERO® 5100 Promoter (5 mg/L)	0.03	0	0	0.02	0	0.01	0.02	0.01
	[1]	[0]	[0]	[1]	[0]	[0]	[1]	[1]
Inhibition assay: AERO® 5100 Promoter (5 mg/L) + sodium benzoate (5 mg/L)	1.01	-	-	-	-	-	-	-
	[60]	-	-	-	-	-	-	-

Sodium benzoate had been degraded to 57% of its ThOD after five days of incubation and 77 and 81% on Days 14 and 28; in the presence of AERO® 5100 Promoter, benzoate had been degraded by 60% after five days. These results confirm that the inoculum was viable and that AERO® 5100 Promoter was not inhibitory to the activity of the inoculum.

Oxygen consumption in bottles containing AERO® 5100 Promoter alone was, at most, 0.03 mg O2/mg or 1% of its ThOD on Day 5. Substances are considered to be readily degradable in this test if oxygen consumption is equal to or greater than 60% of the theoretical value within ten days of the level first exceeding 10%. Thus, AERO® 5100 Promoter cannot be considered to be readily degradable.

Oxygen consumption by Day 28 in control bottles containing inoculated medium (maximum value = 0.42 mg O2/L on Day 21) was acceptable for this assay system (recommended maximum value = 1.5 mg O2/L).

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Description of key information

Not readily biodegradable: 1% after 28 d (OECD 301D)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

One experimental study is available investigating the biodegradation of the substance (Cytec Industries, 1998). The study was performed according to OECD 301D (GLP) with activated sludge from a domestic sewage treatment plant. 5 mg/L of the substance were incubated with activated sludge and mineral medium for 28 d. Measuring the O2 consumption during incubation did not indicate significant biodegradation of the substance. 1% was degraded after 28 d based on O2 consumption. Thus, the substance is not considered to be readily biodegradable according to the OECD criteria. A toxicity control containing both, the test substance and the reference substance, did not indicate inhibition of the inoculum since 60% degradation was recorded on day 5.