Decanoic acid

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

oxygen concentration in test bottles below 0.5 mg/L at test end

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant Hochdahl, Germany
- Initial cell/biomass concentration: 10 E+03 to 10 E+04 cells/mL
- Water filtered: yes
- Type and size of filter used, if any:through a corase paper filter, the first 200 mL were discarded

Duration of test (contact time):

30 d

Initial conc.:

2 mg/L

Based on:

test mat.

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: deionised water was used for the test which is not in line with the guideline.
- Solubilising agent (type and concentration if used): Sodium hydroxide
- Test temperature: 19.9 - 20.1 °C
- pH: 7 - 8
- Aeration of dilution water: aerated until O2 saturation was 8-9 mg O2/L

TEST SYSTEM
- Culturing apparatus: completely filled closed bottles
- Number of culture flasks/concentration: 2

SAMPLING
- Sampling frequency: after 5, 15 and 30 days, which is not in line with the guideline

CONTROL AND BLANK SYSTEM
- Inoculum blank: 4

Reference substance:

other: Dodecylsulfate

Parameter:

% degradation (O2 consumption)

Value:

105

Sampling time:

30 d

Remarks on result:

other: 2 mg/L

Parameter:

% degradation (O2 consumption)

Value:

> 72

Sampling time:

30 d

Remarks on result:

other: 5 mg/L

Details on results:

> 72 % of the test substance was degraded whithin 30 days at a concentration of 5 mg/L. 60% were reached within the given 10 day window as required. Thus, the test substance can be regarded as readily biodegradable.

Parameter:

COD

Value:

2.51 mg O2/g test mat.

Results with reference substance:

The reference substance is readily biodegradable since 90 % was degraded after 30 days and over 60 % in the 10 day window. The ThOD of the reference substance was 2.02 mg O2/ mg dodecylsulfate

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restricitons

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

oxygen concentration was < 0.5 mg/L in test bottles

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewag treatment plant Hochdahl, Germany
- Initial cell/biomass concentration: 10 E+03 - 10 E+05
- Water filtered: yes
- Type and size of filter used, if any: coarse paper filter

Duration of test (contact time):

30 d

Initial conc.:

2 mg/L

Based on:

test mat.

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: test substance with dilution water and solubility agent
- Solubilising agent (type and concentration if used): sodium hydroxide
- pH: 7 - 8
- Aeration of dilution water: prior to the application the water was aerated until O2 saturation was 8-9 mg O2/L
- Other: The dilution water was deionised water instead of nutrient medium as claimed by the guideline

TEST SYSTEM
- Culturing apparatus: closed bottles
- Number of culture flasks/concentration: 2

SAMPLING
- Sampling frequency: after 0, 5, 15 and 30 d. This is not in line with the guideline, since sampling is supposed to be every 3 - 4 days for the assessment of the 10 day window

CONTROL AND BLANK SYSTEM
- Inoculum blank: 4 duplications
- Toxicity control: 2 duplications
- Other: inoculated medium with emulsifier: 4

Reference substance:

other: dodecylsulfate

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

30 d

Remarks on result:

other: 2 mg/L

Parameter:

% degradation (O2 consumption)

Value:

62

Sampling time:

30 d

Remarks on result:

other: 5 mg/L

Details on results:

Within the 10-day time window the 60% level was passed. After 30 days the degradation was at 86% for 2 mg a.s./L and at 62% for 5 mg a.s./L. Thus, the test substance is regarded readily biodegradable.

Parameter:

COD

Value:

2.88 mg O2/g test mat.

Results with reference substance:

Dodecylsulfate also passed the 60 % level within 10 days. After 30 days the degradation was 89% and the ThOD was 2.02 O2/ mg reference substance.

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the category justification provided in IUCLID section 13.

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

30 d

Remarks on result:

other: 2 mg/L

Remarks:

Source: CAS 143-07-7

Parameter:

% degradation (O2 consumption)

Value:

62

Sampling time:

30 d

Remarks on result:

other: 5 mg/L

Remarks:

Source: CAS 143-07-7

Parameter:

% degradation (O2 consumption)

Value:

105

Sampling time:

30 d

Remarks on result:

other: 2 mg/L

Remarks:

Source: 124-07-2

Parameter:

% degradation (O2 consumption)

Value:

> 72

Sampling time:

30 d

Remarks on result:

other: 5 mg/L

Remarks:

Source: 124-07-2

Parameter:

COD

Value:

2.88 mg O2/g test mat.

Remarks on result:

other: Source: 143-07-7

Parameter:

COD

Value:

2.51 mg O2/g test mat.

Remarks on result:

other: Source: 124-07-2

Description of key information

Biodegradation: readily biodegradable: 62 – 105 % after 30 d (O2 consumption, OECD 301 D)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

No study on the biodegradation of decanoic acid in water is available. Therefore, read across from the key studies of a shorter (octanoic acid, C8) and a longer-chain fatty acid (lauric acid, C12), which are members of the fatty acid category, was conducted.

The study with octanoic acid (2004) was performed according to OECD 301D (non-GLP) where the substance was tested at concentrations of 2 and 5 mg/L for 30 days. At a test substance concentration of 5 mg/L more than 72% was degraded within 30 days. Due to the good biodegradability at 5 mg/L, the oxygen concentration remained inadequate so that the 72% degradation should be regarded as a minimum value. At a test concentration of 2 mg/L octanoic acid was completely degraded. 60% degradation was reached within the 10 day window as required. Thus, octanoic acid can be regarded as readily biodegradable.

The read across from lauric acid (C12) to decanoic acid (C10) is based on the key study of lauric acid (2001). The test was performed in a closed bottle test according to OECD 301D. After 30 days 86% oxygen consumption at a substance concentration of 2 mg/L and 62% at 5 mg/L were observed. The 10-day window criterion was met.

Based on the ready biodegradability of the category members octanoic and lauric acid, decanoic acid can be regarded as readily biodegradable, too. This assumption is consistent with the hazard assessment presented in the OECD SIDS (2009) for the category “Aliphatic Acids Category” where aliphatic fatty acids with a carbon chain length in the range of C8 – C22 were judged to be readily biodegradable.