Sodium 2-butoxyethyl sulphate

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:

19 Oct - 16 Nov 2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Regulation (EC) No 648/2004 01 the Eurapean Parliament and 01 the Couneil

Version / remarks:

31 March 2004 on detergents (OJ L 104, 804.2004)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from the aeration tank of a municipal biological waste water treatment plant: ARA Werdhölzli, Zürich, Switzerland (18 Oct 2004; 2.00 p.m)
- Storage length: activated sludge was used immediately after sampling from the treatment plant
- Preparation of inoculum for exposure: Prior to the test the sludge was washed twice with tap water. To prepare the stock solution the test material was dissolved in a double concentration in the test medium. An appropriate amount of this stock solution was diluted with test medium to give a final test concentration of 100 mg/L.
- Pretreatment: no feed, test item and funtional control as sole organic carbon source
- Initial cell/biomass concentration: 30 mg/L dry matter in the final mixture

Duration of test (contact time):

28 d

Initial conc.:

93 mg/L

Based on:

act. ingr.

Remarks:

100 mg/l of test material with 93% active ingredient

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Aerobic mineral salts medium according to the guideline, prepared with deionised water
- Test temperature: 22 ± 0.5 °C
- pH: inoculum blanks 7.5; procedure control 8.1, test suspension: 7.2
- pH adjusted: yes to 7.4
- Conductivity: <1.5 µS/cm
- DOC: <0.3 mg/L (test medium)
- Suspended solids concentration: 30 mg/L dry matter
- Continuous darkness: yes (thermostat cabinet in the dark)

TEST SYSTEM
- Culturing apparatus: 500 mL glass bottles (tightly closed with manometrie BOD measuring devices); containing 200 mL total volume; bottles are equipped with stirring rods and butyl rubber quivers which contain 2 pellets of sodium hydroxide each to absorb the produced CO2 from the head space
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: test vessels were stirred by an inductive stirring system for a maximum test period of 28 days.
- Measuring equipment: During the test the O2 uptake was continuously measured with a manometrie BOD measuring device (OxiTop®-C measuring head (WTW Wissenschaftlich-Technische Werkstätten GmbH & Co. KG, Weilheim, Germany). Ultimate biodegradation was determined by analysis of dissolved organic carbon (DOC) concentrations at the beginning and at the end of the test (Shimadzu 5050 TOC-Analyzer using the NPOC-mode)

SAMPLING
- Sampling frequency: continously

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates
- Abiotic sterile control: not determined
- Toxicity control: not determined
- Other: Functional control (reference) 1 replicate

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

62

Sampling time:

28 d

Details on results:

The lag-phase last until day 17 (7.0% degradation). At day 18 13.1% degradation was achieved and 60% after day 26 so the 10-day window was fulfilled (see table 1 in section "Any other information on results incl. tables").

Results with reference substance:

The procedure control sodium benzoate reaehed 80% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

The ThOD value of the test substance was calculated from the molecular formula. The ThOD value was 1.235 mg O2/mg of test material.

The ThOD of the reference eompound sodium benzoate was calculated to be 1.665 mg O2/mg substance.

Table 1: O2 uptake of the test units, the inoculum blank and the corresponding degradation data

	Inoculum blank *	Test unit no. 1 containing test material		Test unit no. 2 containing test material
Time (days)	BOD (mg O2/L)	BOD (mg O2/L)	Degradation (%) **	BOD (mg O2/L)	Degradation (%) **	Mean Degradation of no. 1+2 (%)
0	0.0	0.0	0.0	0.0	0.0	0.0
1	5.0	8.0	2.6	8.0	2.6	2.6
2	9.0	8.0	-0.9	10.0	0.9	0.0
3	11.0	12.0	0.9	14.0	2.6	1.7
4	13.0	14.0	0.9	16.0	2.6	1.7
5	15.0	16.0	0.9	18.0	2.6	1.7
6	16.0	18.0	1.7	18.0	1.7	1.7
7	18.0	20.0	1.7	20.0	1.7	1.7
8	18.0	22.0	3.5	22.0	3.5	3.5
9	20.0	22.0	1.7	22.0	1.7	1.7
10	20.0	24.0	3.5	22.0	1.7	2.6
11	22.0	24.0	1.7	24.0	1.7	1.7
12	22.0	24.0	1.7	26.0	3.5	2.6
13	22.0	24.0	1.7	26.0	3.5	2.6
14	22.0	26.0	3.5	28.0	5.2	4.4
15	24.0	26.0	1.7	28.0	3.5	2.6
16	24.0	28.0	3.5	34.0	8.7	6.1
17	25.0	28.0	2.6	38.0	11.3	7.0
18	25.0	30.0	4.4	50.0	21.8	13.1
19	26.0	30.0	3.5	67.9	36.5	20.0
20	26.0	32.0	5.2	87.9	53.9	29.6
21	27.0	34.0	6.1	91.9	56.5	31.3
22	28.0	38.0	8.7	95.9	59.1	33.9
23	27.0	48.0	18.3	97.9	61.7	40.0
24	28.0	57.9	26.0	99.9	62.6	44.3
25	28.0	77.9	43.4	102.0	64.4	53.9
26	28.0	91.9	55.6	102.0	64.4	60.0
27	30.0	93.9	55.6	106.0	66.2	60.9
28	30.0	95.9	57.4	106.0	66.2	61.8

*            Mean of two replicates

**         The calculation is based on the nominal concentration of the test substance of 93 mg/L and a theoretical O2 demand (ThOD) in mg O2/mg test substance of 1.235

Table 2: O2 uptake of the procedure and toxicity control, the inoculum blank, the abiotic sterile control and the corresponding degradation data

	Inoculum blank	Procedure control containing sodium benzoate		Toxicity control containing test material+sodium benzoate		Abiotic sterile control
Time (days)	BOD (mg O2/L)	BOD (mg O2/L)	Degradation (%)**	BOD (mg O2/L)	Degradation (%)**	BOD (mg O2/L)
0	0.0	0.0	0.0	n.d.		n.d.
1	5.0	44.0	23.4	n.d.		n.d.
2	9.0	76.9	40.8	n.d.		n.d.
3	11.0	102.0	54.6	n.d.		n.d.
4	13.0	114.0	60.7	n.d.		n.d.
5	15.0	123.0	64.9	n.d.		n.d.
6	16.0	130.0	68.5	n.d.		n.d.
7	18.0	135.0	70.3	n.d.		n.d.
8	18.0	139.0	72.7	n.d.		n.d.
9	20.0	143.0	73.9	n.d.		n.d.
10	20.0	147.0	76.3	n.d.		n.d.
11	22.0	150.0	76.9	n.d.		n.d.
12	22.0	151.0	77.5	n.d,		n.d.
13	22.0	154.0	79.3	n.d.		n.d.
14	22.0	156.0	80.5	n.d.		n.d.
15	24.0	157.0	79.9	n.d.		n.d.
16	24.0	159.0	81.1	n.d.		n.d.
17	25.0	160.0	81.1	n.d.		n.d.
18	25.0	162.0	82.3	n.d.		n.d.
19	26.0	163.0	82.3	n.d.		n.d.
20	26.0	166.0	84.1	n.d.		n.d.
21	27.0	166.0	83.5	n.d.		n.d.
22	28.0	167.0	83.5	n.d.		n.d.
23	27.0	170.0	85.9	n.d.		n.d.
24	28.0	169.0	84.7	n.d.		n.d.
25	28.0	170.0	85.3	n.d.		n.d.
26	28.0	171.0	85.9	n.d.		n.d.
27	30.0	171.0	84.7	n.d.		n.d.
28	30.0	173.0	85.9	n.d.		n.d.

*Mean of two replicates

**The calculation is based on the nominal concentration of sodium benzoate of 100 mg/L and a theoretical O2 demand (ThOD) in mg O2/mg test substance of 1.665

n.d. not determined

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Readily biodegradable according to the OECD criteria (62% degradation after 28 d, OECD 301 F).

Description of key information

Readily biodegradable according to the OECD criteria (62% degradation after 28 d, OECD 301 F).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

One biodegradation screening study according to OECD 301 F (GLP) is available for the substance (BMG Engineering, 2005). Non-adapted, domestic activated sludge from a sewage treatment plant was used as inoculum. At the end of the 28 -day exposure period 62% degradation based on O2 measurement was determined and the 10 -day window criterion was fulfilled. Thus the substance can be considered as readily biodegradable.