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EC number: 204-677-5
CAS number: 124-07-2
Fatty acids are ubiquitous and dynamic
in the environment and are metabolised in water and soil by
microorganisms. Fatty acids occur in the environment both naturally and
via anthropogenic uses. Microbial metabolism is the primary route of
degradation in the environment while fatty acids are an integral part of
the cell membranes of every living organism from bacteria and algae to
higher plants and animals. Each of these organisms contain fatty acids
as part of their food reserves and consume them to produce energy
required for anabolic and catabolic metabolism.
In water fatty acids are abiotically
stable (OECD SIDS, 2009). Based on the ready biodegradability and
molecular structure (aliphatic, mostly saturated carbon chains)
hydrolysis is not a relevant degradation pathway and thus was not
tested. Modelled data on the photodegradation in air are available for
aliphatic fatty acids of C6-C22 carbon chain length. The data show a
decreasing photodegradation half-life with increasing chain length.
Unsaturated fatty acids undergo photolysis faster than saturated. The
half-life declines with the number of double bounds. The calculated
half-lives are in the range of 23.24 hours for hexanoic acid (C6) to
4.56 hours for docosanoic acid (C22) (OECD SIDS, 2009). Direct
photolysis is not expected to contribute appreciably to the overall
breakdown rate in water and soil, since the environmental degradation of
these substances is predominantly of biotic nature.
The data set for
biodegradation includes standard biodegradation studies as well as data
obtained by valid QSAR models. As summarized in the category
justification, the members of the fatty acid category demonstrates ready
biodegradability. This 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 C6 – C22 were described to be readily biodegradable.
to sediment and soil is shown for fatty acids starting at a chain length
of 14 and higher indicated by a log Koc value of approximately 3 (C14).
Accordingly, fatty acids with a shorter chain length partition mainly to
the water phase. The members of the fatty acids category with chain
length greater than 14 have a low potential of mobility in soil based on
high Koc values and low water solubility.
Volatilisation is not expected to be a
significant transport process or dissipation route for fatty acids in
The log Pow of fatty acids are in the
range of 1.57 (C6) to 9.91 (C22). This suggests that some fatty acids
may tend to bioconcentrate in the environment. A
fish bioaccumulation study is available for a C12 fatty acid-sodium
laurate which showed negligible evidence of bioaccumulation potential in
fish tissues with an estimated BCF of 225 L/kg after 28 days exposure.
As fatty acids are
naturally stored in the form of triacylglycerols primarily within fat
tissue until they are used for energy production (fat storage tactic),
it is therefore considered that there will be no risk to aquatic
organisms from bioconcentration/biomagnification of fatty acids.
the range of log Koc values given suggests that some fatty acids may be
expected to adsorb to sediment. It is considered that rapid
biodegradation and the ubiquity of fatty acids will not have any
environmental relevance. Therefore it is considered that there will be
no risk to sediment dwelling organisms.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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