Alcohols, C9-11, branched and linear, ethoxylated, sulfates, sodium salts

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:

27 Oct – 24 Nov 2005

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

ISO 14593:1999 (Water quality - Evaluation of ultimate aerobic biodegradability of organic compounds in aqueous medium - Method by analysis of inorganic carbon in sealed vessels (CO2 headspace test))

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK; secondary treatment stage
- Pretreatment: for reduction of inorganic carbon (IC) content of inoculum, the filtrate was sparged with CO2-free air for 1 hour whilst maintaining its pH at 6.5 using concentrated orthophosphoric acid. Afterwards pH was restored to its original value of 7.8 using 7 M sodium hydoxide.
- Water filtered: yes
- Type and size of filter used, if any: coarse filter paper

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

other: total carbon

Initial conc.:

126.5 mg/L

Based on:

test mat.

Initial conc.:

2.14 mg/L

Based on:

ThIC

Parameter followed for biodegradation estimation:

inorg. C analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: standard culture medium
- Test temperature: 20 +/- 1°C
- pH: 7.8
- Aeration of dilution water: Aeration with CO2 free air
- Continuous darkness: yes
- Other: constant shaking at 150 rpm

TEST SYSTEM
- Culturing apparatus: 125 mL glass bottles, filled with 107 ml, sealed with Teflon lined silicon septa
- Number of culture flasks/concentration: 6
- Other: headspace to liquid ratio of 1:2

SAMPLING
- Sampling frequency: day 0, 14, 28


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 6 replicates
- Reference substance: yes, 6 replicates
- Toxicity control: yes,

Reference substance:

other: sodium benzoate

Parameter:

% degradation (inorg. C analysis)

Value:

1

Sampling time:

0 d

Parameter:

% degradation (inorg. C analysis)

Value:

83

Sampling time:

14 d

Parameter:

% degradation (inorg. C analysis)

Value:

104

Sampling time:

28 d

Results with reference substance:

Sodium benzoate attained 89% degradation after 28 days

Table 1: Percentage Biodegradation Values

Day	% Degradation Sodium Benzoate			% Degradation Test Material
	R1	R2	Mean	R1	R2	Mean
0	0	0	0	1	1	1
14	99	103	101	82	84	83
28	83	95	89	102	106	104

Table 21: Validity criteria

Criterion from the guideline	Outcome	Validity criterion met
The test is considered valid if the standard material degradation rate is ≥ 60% by Day 14.	89%	yes
The toxicity control should attain ≥ 25% degradation by Day 14 for the test material to be considered as non-inhibitory.	Results not given
The TIC produced from the control bottles at the end of the test should be ≤ 15% of the TOC added initially as test material.	2%	yes

 

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: 100% (inorg. C) in 28 days (ISO 14593)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The ready biodegradability of Alcohols, C9-11, branched and linear, ethoxylated, sulfates, sodium salts was investigated in a study following ISO 14593 (GLP). The biodegradation rate was estimated by inorganic C analysis. A degradation rate of 104 % after 28 days was determined.