Fatty acids, C8-18 and C18-unsatd., esters with neopentyl glycol

Toxicity to soil microorganisms

Administrative data

Endpoint:

toxicity to soil microorganisms

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted specific principles, acceptable for assessment.

Data source

Reference

Reference Type:

publication

Title:

Triglyceride degradation in soil

Author:

Hita, C.; Parlanti, E.; Jambu, P.; Joffre, J.; Amblès, A.

Year:

1996

Bibliographic source:

Org. Geochem 25(1-2): 19-28

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The degradation of the model molecule (pure tristearin) was investigated in three different soil types, to determine the behavior of fatty wastes.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Tristearin

IUPAC Name:

Tristearin

Constituent 2

Reference substance name:

Glycerol tristearate

EC Number:

209-097-6

EC Name:

Glycerol tristearate

Cas Number:

555-43-1

Molecular formula:

C57H110O6

IUPAC Name:

propane-1,2,3-triyl trioctadecanoate

Sampling and analysis

Analytical monitoring:

yes

Test substrate

Vehicle:

no

Details on preparation and application of test substrate:

APPLICATION OF TEST SUBSTANCE TO SOIL
- Method: The three soil samples were first sieved (<2mm), adjusted to 2/3 of the water-holding ca¬pacity of each respective soil and then weighed into 750 cm3 flasks in portions calculated to correspond to 100 g o.d. soil. The soils were subsequently supplemented with a pure triglyceride.

Test organisms

Test organisms (inoculum):

soil

Study design

Total exposure duration:

8 wk

Test conditions

Test temperature:

20 °C

Details on test conditions:

TEST SYSTEM
- Test container: flask
- Amount of soil: 100 g
- No. of replicates per concentration: yes, 3 replicates
- No. of replicates per control: yes, 3 replicates

VEHICLE CONTROL PERFORMED: no

Nominal and measured concentrations:

0.2% (wt/wt)

Results and discussion

Effect concentrations

Remarks on result:

other: Precise results cannot be given, see explanation in any other information on results incl. tables.

Any other information on results incl. tables

Free lipids were extracted from representative samples and of the combined replicates of each control and supplemented soil. The concentration of free lipids extracted after 1 and 4 weeks from each series. After the first week a low diminution of total free lipids was observed (GOV: 2.7%; CHA: 2.6%; SOR: 3.5%). After 4 weeks, the amount of free lipids decreased (CHA: 11%; SOR: 8%; GOV: no variations). Fluctuations of lipid concentrations observed with time in the control were attributed to an increased activity of soil microorganisms due to the incubation. The main result was the great increase during the first week of the acid + polar fractions. This probably indicates the oxidation and hydrolysis process of the added compound. The amounts decreased when the incubation prolonged to 4 weeks. These compounds did not accumulate as they are certainly intermediate compounds in the biodegradation process. The evolution of the concentrations of monoacid and di-, keto- and hydroxy- acid fractions significantly increased during the first week. After 4 weeks a decrease of quantities was followed. The increase obtained during the first week. Monocarboxylic acids were then predominant over di-, keto- and hydroxylacids in the three soils. The results show that, due to the soil supplementation with tristearin, free fatty acids were produced. After soil microflora adaption, these compounds are utilized as they are freed by enzymatic hydrolysis. A part of the of the monocarboxyclic acids is probably oxidized to form di-, keto- and hydroxyl-acids. Contrary the acid fractions evolution, the amounts of the neutral fractions increased between 1 and 4 weeks in the supplemental soils. This is due to the increase of the quantity of alcohols and polar neutral compounds. Bio-oxidation processes seem to be more efficient after 4 weeks. After 1 week also a low decrease, compared to the controls, in the amounts of hydrocarbons consecutive to a low increase of the ester fractions.

Main result of the monoacid fractions analysis was the rapid formation of stearic acid in considerable amounts. This result showed that an intense hydrolysis reaction with specific lipase of tristearin had occurred after the soil supplementation. The investigations of ester fractions showed that new alkanoic acids (methyl stearate, ethyl stearate, and propyl stearate), not determined in the controls, were generated in the supplemented soils. Among other processes the following hypothesis to explain the formation of these compounds were proposed:

1.      Bioesterification of a part of the free stearic acid, released by an enzymatic hydrolysis reaction

2.      Alcoholysis of the triglyceride to form esters, directly

3.      And/or direct formation of these compounds from tristearin with C-C and C-O bond cleavages