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Ecotoxicological information

Biotransformation and kinetics

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Administrative data

Endpoint:
biotransformation and kinetics
Remarks:
Fatty acids metabolism data
Type of information:
other: Data compilation in freely accessible reports
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Cross-reference
Reason / purpose for cross-reference:
data waiving: supporting information
Reference
Endpoint:
bioaccumulation in aquatic species: fish
Data waiving:
other justification
Justification for data waiving:
other:
Justification for type of information:
The full list of bibliographical references cited in the justification for data waiving is provided in the Endpoint Summary of Section 5.3.1. When appropriate, Endpoint Study Records were created in the relevant IUCLID sections to reflect these bibliographical data (see the field "Cross-references" below).
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information
Reason / purpose for cross-reference:
data waiving: supporting information

Data source

Referenceopen allclose all

Reference Type:
other: Data compilation in freely accessible report
Title:
Final report on the safety assessment of isostearic acid
Author:
CIR
Year:
1983
Bibliographic source:
Journal of the American College of Toxicology 2 (7): 61-401
Reference Type:
other: Data compilation in freely accessible report
Title:
Final report on the safety assessment of oleic acid, lauric acid, palmitic acid, myristic acid, stearic acid
Author:
CIR
Year:
1987
Bibliographic source:
Journal of the American College of Toxicology 6 (3): 321-401

Materials and methods

Test material

Constituent 1
Reference substance name:
Fatty acids
IUPAC Name:
Fatty acids
Details on test material:
General information on fatty acids without testing.
Specific details on test material used for the study:
CIR (1983, 1987) are freely accessible reports containing data compilation on isostearic acid and fatty acids without testing them. CIR (1983) described isostearic acid as a clear, oily liquid with little odor which is insoluble in water.

Results and discussion

Any other information on results incl. tables

- CIR (1983): Acyl coenzyme A synthetase of rat liver homogenate was found to activate isostearic acid. Iso-fatty acids are metabolized in a way similar to that of straight-chain fatty acids by the mitochondrial and michrosomal fractions or rat liver homogenate. In contrast, however, with the straight-chain fatty acids which are sucessively oxidized at the β carbon to yield two carbon fractions, the iso-fatty acids are also oxidized to a large extent at the ω carbon to ultimately form three carbon dicarboxylic acids. The enzymes catalysing the ω-hydroxylation are present in the mitochondrial and michrosomal fractions of liver homogenate, whereas the enzymes catalysing the further oxidation into carboxylic acids have been demonstrated in the soluble fraction.

 

- CIR (1987): Fatty acids have been found in marine and freshwater organisms, bacteria, and vegetable oils and animal fats. Although mammalian tissues normally contain trace amounts of free fatty acids, conjugated forms can be found in several tissues. Free fatty acids have been found in human sebum and epidermal tissue.

Proposed mechanisms for fatty acid uptake by different tissues range from passive diffusion to facilitated diffusion or a combination of both. Fatty acids taken up by the tissues can either be stored in the form of triglycerides (98% of which occurs in adipose tissue depots) or they can be oxidized for energy via the β-oxidation and tricarboxylic acid cycle pathways of cataboIism. The β-oxidation of fatty acids occurs in most vertebrate tissues (except the brain) using an enzyme complex for the series of oxidation and hydration reactions resulting in the cleavage of acetate groups as acetyl-CoA (coenzyme A). Alternate oxidation pathways can be found in the liver (ω-oxidation) and in the brain (α-oxidation). Fatty acid biosynthesis from acetyl-CoA takes place primarily in the liver, adipose tissue, and mammary glands of higher animals. Successive reduction and dehydration reactions yield saturated fatty acids up to a 16-carbon chain length.

Applicant's summary and conclusion

Executive summary:

These freely accessible reports contain data showing that isostearic acid and fatty acids are metabolized; which is part of the arguments used to waive the information requirement in Section 5.3.1 (Bioaccumulation: aquatic/sediment).