Decanoic acid

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

13 Oct - 17 Nov 1978

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Inconsistent results

Qualifier:

no guideline followed

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Sample was weighed in clean, dried and tared one milliliter beakers and then introduced into the CAD flask or BOD dilution bottle.

Test organisms (species):

other: "biological seed"

Test type:

not specified

Water media type:

not specified

Limit test:

no

Remarks on exposure duration:

no data

Reference substance (positive control):

no

Details on results:

No results are given in the study report. It is considered to be invalid, since the measured oxygen demand was higher than the theoretical oxygen demand.

Reference 2

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

other information

Study period:

not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

other: Only short abstract available

Qualifier:

no guideline followed

Principles of method if other than guideline:

Bacillus subtilis was tested with different substances and the optical densitiy measured after 1 h to calculate the inhibition.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Inoculum was placed into plastic tubes or Erlenmeyer flasks which already contained the test substance
- Controls: 2 with solvent, 2 with distilled water
- Chemical name of vehicle: Ethanol, dimethylsulfoxide, sodium hydroxide or distilled water

Test organisms (species):

Bacillus subtilis

Details on inoculum:

- Pretreatment: Plated with tryptose blood agar base (33 g/L) were inoculated from single colonies of Bacillus subtilis and incubated for 7 h. Afterwards the cells were supended and diluted at different low titers into three flasks containing the MCV medium and shaken at room temperature overnight. If the cultures had not grown overnight beyond an optical density at 600 nm (OD600) of 1.0 it was not used. The cultures reaching 1.0 were utilised for the test.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

60 min

pH:

7.2, adjusted with KOH

Details on test conditions:

TEST SYSTEM
- Test vessel: Plastic tubes or Erlenmeyer flasks
- Aeration: Tubes were aerated.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: MCV medium contains 1.4% K2HPO4 , 0.6% KH2PO4, 0.2% MgSO4 * 7 H2O, 0.1% sodium citrate, 25 µg/mL L-tryptophan, 10 µg/mL L-methionine and 1 % vitamin-free casein hydrolysate

OTHER TEST CONDITIONS
- Adjustment of pH: with KOH to 7.2

EFFECT PARAMETERS MEASURED: optical density at 600 nm after 60 min in the plastic tubes and after 15 or 20 min in the Erlenmeyer flasks

Reference substance (positive control):

no

Duration:

60 min

Dose descriptor:

EC50

Effect conc.:

0.25 mmol/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Reference 3

Endpoint:

toxicity to microorganisms

Type of information:

experimental study

Adequacy of study:

other information

Study period:

not reported

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

no guideline followed

Principles of method if other than guideline:

Six different bacteria were anaerobically incubated and the turbitidy measured to determine inhibition on growth.

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test solution was prepared by dissolving measured quantities of the test substance in absolute ethanol. First a 250 mM stock solution was prepared and then further diluted with ethanol to 200, 175, 150, 125, 100, 75, 50, 25, 10, 5 and 2.5 mM.
- Controls: Since the test compund produces culture turbidity, a dilution series with medium and test compound without inoculum were prepared.

Test organisms (species):

other: Bifidobacterium bifidum type a, Bifidobacterium bifidum type b, Bifidobacterium infantis sp infantis type a, Bifidobacterium infantis sp infantis type b, Escherichia coli, Salmonella typhimurium

Details on inoculum:

- Preparation of inoculum for exposure: The PYG medium was dispensed into a 500 mL screw-capped bottle and sterilised at 121 °C for 15 min. While cooling, 3.0 mL were delivered into metal capped culture tubes which were inoculated with 0.03 mL of the substance stock solutions (2.5 - 20 mM). The culture tubes were placed in an anaerobic cabinet and maintained at 37°C over night. Oxygen free gas (20% nitrogen in hydrogen) was supplied.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

29 h

Test temperature:

37 °C

pH:

4.5 - 6.6, the pH was measured in the highest and lowest substance concentrations.

Nominal and measured concentrations:

Nominal: 200, 175, 150, 125, 100, 75, 50, 25, 10, 5 and 2.5 mM

Details on test conditions:

TEST SYSTEM
- Test vessel: culture tubes
- No. of vessels per control (replicates): one series (2.5 - 200 mM test substance) with test substance without inoculum to determine turbidity

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The PYG media (Petone-yeast extract glucose) with 1% glucose, was prepared and dispersed anaerobically and sterilised. Anaerobic culture counts were performed on PYG-agar roll tubes.

OTHER TEST CONDITIONS
- Adjustment of pH: no

EFFECT PARAMETERS MEASURED: turbidity after 29 h

Reference substance (positive control):

no

Duration:

29 h

Dose descriptor:

EC50

Effect conc.:

50 other: nmol

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: B. bifidum type a

Duration:

29 h

Dose descriptor:

EC50

Effect conc.:

2.5 other: nmol

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: B. bifidum type b

Duration:

29 h

Dose descriptor:

EC50

Effect conc.:

2.5 other: nmol

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: B. infantis sp infantis type a

Duration:

29 h

Dose descriptor:

EC50

Effect conc.:

2.5 other: nmol

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: B. infantis sp infantis type b

Duration:

29 h

Dose descriptor:

EC50

Effect conc.:

0 other: nmol

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Remarks on result:

other: S. typhimurium

Details on results:

The test substance had a positive effect on E. coli growth.

Reference 4

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

other information

Study period:

19 Feb 1988

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

study was performed for only 30 min

Qualifier:

according to guideline

Guideline:

other: DIN 38412 part 27

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

duration of exposure only 30 min.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Pseudomonas putida

Details on inoculum:

- Laboratory culture: Strain Berlin 33/2 (DSM 50026)
- Preparation of inoculum for exposure: direct weight of test substance into test vessels, filled up to 100 mL with drinking water, 5 min treatment with ultrasound

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Details on test conditions:

TEST SYSTEM
- Material, size, headspace, fill volume: 100 mL Erlenmeyer flasks with 100 mL test medium
- Aeration: directly over the surface of the test solution
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: drinking water (copper- and chlorine-free)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : oxygen consumption after 30 min

Reference substance (positive control):

no

Duration:

30 min

Dose descriptor:

EC0

Effect conc.:

3 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

30 min

Dose descriptor:

EC10

Effect conc.:

10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Table 1: O2-consumption after 30 min

Concentration [mg/L]	O2-consumption [mg O2/(L*min)]
0 (control 1)	2.7
0 (control 2)	2.9
0 (control 3)	3.2
0 (control 4)	3.2
3000	2.4
10000	2.8

Description of key information

EC10 (18 h) = 912 mg/L (ISO 10712); RA CAS 124-07-2

Key value for chemical safety assessment

EC50 for microorganisms:

912 mg/L

Additional information

Good quality read across data from octanoic acid are used as key information to assess the toxicity of decanoic acid to microorganisms, due to deficiencies of the available data on decanoic acid.

The toxicity of the read across substance octanoic acid towards Pseudomonas putida, is evaluated in a cell multiplication inhibition test (1988). The study was conducted similarly to ISO 10712. The test organism was exposed to a wide range of nominal concentrations (0.266 - 1088.00 mg/L) and an EC10 (18h) of 912 mg/L (nominal) was determined.

A further study, investigating the toxicity of the substance to Pseudomonas putida, is available for decanoic acid and was performed according to DIN 38412 part 27. The study resulted in an EC0 (30 min) of 3000 mg/L and an EC10 (30 min) of 10,000 mg/L based on respiration rate. However, the study was not used for further assessment due to the short duration of the experiment.

An additional study (1978) is available conducted with biological seed as the test organisms but was rated unreliable (RL3) due to inconsistent results and poor reporting.

Supportive information is withdrawn from short abstracts of two publications. In the first study (Freese, 1979) conducted with Bacillus subtilis, a EC50 of 0.25 mmol/L was obtained after 60 min. In the second study (Powell and May, 1981) with six different bacterial strains incubated anaerobically, different sensitivity of the various organisms to decanoic acid were observed. However, due to limited documentation and consequently limited information, these two literature studies were rated as not assignable.