Octadecan-1-ol, ethoxylated

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:

28 Apr - 26 May 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

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 (e.g. location, sampling depth, contamination history, procedure): activated sludge from the municipal wastewater treatment plant "Breisgauer Bucht"
- Preparation of inoculum for exposure: the activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in aerated tap water.
- Concentration of sludge: 30 mg dry solids/L

Duration of test (contact time):

25 d

Initial conc.:

ca. 20 mg/L

Based on:

TOC

Initial conc.:

ca. 42 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium acc. to guideline
- Test temperature: 21.0 to 22.0 °C
- Suspended solids concentration: 30 mg dry solids per litre
- Continuous darkness: diffuse light


TEST SYSTEM
- Culturing apparatus: Gas wash bottles (2000 ml volume) with lateral connecting pieces for butyl rubber septums were used as reactors.
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: aeration with carbon dioxide free air.
- Details of trap for CO2 and volatile organics if used: 72 9 NaOH were dissolved in 9000ml deionised water in closed recipients (0.2 M NaOH). The inorganic carbon concentration of the 0.2 M NaOH was determined.

SAMPLING
- Sampling frequency: On the 4th,7th,11th,14th,21stand 28thday

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 replicates
- Procedure control: 3 replicates
- Toxicity control: 1 replicate (5.15 ml of a stock solution of 10 g/I reference substance and 42.0 mg of the test item were added directly into the vessel.)

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

83.6

Sampling time:

28 d

Details on results:

The degradation in the toxicity control was 85.9% within 14 days and 82.3% within 28 days

Results with reference substance:

The reference substance reached > 90% degradation after 14 days.

Table 1 Degradation rate

	Biodegradation (%)
Day	0	4	7	11	14	21	28	28 (after acidification
Test substance, 1^streplicate	0	7.7	52.5	77.2	87.2	86.2	82.9	87.7
Test substance, 2^ndreplicate	0	28.0	67.3	87.2	91.2	86.7	93.2	88.5
Test substance, 3^rdreplicate	0	9.1	57.0	74.9	74.9	77.7	79.5	74.5
Test substance, mean of two replicates	0	14.9	58.9	79.8	84.4	83.5	85.2	83.6

Table 2: Validity criteria OECD 301 B

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	<10%	yes
Percentage degradation of the reference compound reached the pass level by day 14 (≥ 60%).	>90% after 14 days.	yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	85.9% after 14 days	yes
The IC content of the test substance suspension in the mineral medium at the beginning of the test must be less than 5% of the TC.	<5%	yes
The total CO2 evolution in the inoculum blank at the end of the test should not normally exceed 40 mg/L medium and must be below 70 mg/I.	41.5 mg/L	yes

Validity criteria fulfilled:

yes

Remarks:

Please refer to table 2 at "Any other information on results incl. tables"

Description of key information

Readily biodegradable: 83.6% in 28 days (OECD 301B)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The ready biodegradability of octadecan-1-ol, ethoxylated, < 2.5 EO was investigated in a GLP study according to OECD guideline 301B. Based on CO2 evolution, the test item added at a concentration of 42 mg/L, attained 83.6% degradation after 28 days of incubation.

A study conducted according to OECD guideline 301C, for which only short abstract is available, determined a degradation rate of 57%.