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EC number: 270-302-7
CAS number: 68424-43-1
The available information showed some evidence that Lanolin fatty acids, is expected to be absorbed via the gastro-intestinal tract. Once absorbed, the substance may be distributed systemically and is supposed to be metabolised within the standard metabolic pathways for fatty acids resulting in complete oxidation to CO2. Biliary excretion may well be a significant route of excretion for the unmetabolised part of the substance.
In accordance with Annex VIII, Column 1, Item 8.8.1, of Regulation
(EC) 1907/2006 and with Guidance on information requirements and
chemical safety assessment Chapter R.7c: Endpoint specific guidance
(ECHA, 2012), assessment of the toxicokinetic behaviour of the substance
is conducted to the extent that can be derived from the relevant
available information. This comprises a qualitative assessment of the
available substance specific data on physicochemical and toxicological
properties according to the relevant Guidance (ECHA, 2012). There are no
studies available in which the toxicokinetic behaviour of Lanolin fatty
acids (CAS 68424-43-1) has been investigated.
Lanolin fatty acids is a UVCB substance, composed of fatty acids
derived from the saponification of lanolin.Lanolin fatty acids is a
brown waxy solid with a molecular weight range of 175 – 439 g/mol.
Lanolin fatty acids has a melting temperature of 35-60°C at normal
pressure (Atkinson, 2010), a low water solubility of 0.21 mg/L (Cook,
2010), vapour pressure of <700 Pa at 20 °C (Younis, 2012), and log Pow
of 1.34 - >6.5 (Walker, 2013). Supporting values for the main
representative components are 4.43 - >13.87 (calculated with EPI suiteTM).
Absorption is a function of the potential for a substance to
diffuse across biological membranes. The most useful parameters
providing information on this potential are the molecular weight, the
octanol/water partition coefficient (log Pow) value and the water
solubility. The log Pow value provides information on the relative
solubility of the substance in water and lipids (ECHA, 2012).
In general, molecular weights below 500 and log Pow values between
-1 and 4 are favourable for absorption via the gastrointestinal (GI)
tract, provided that the substance is sufficiently water soluble (> 1
mg/L). Lipophilic compounds may be taken up by micellar solubilisation
by bile salts, but this mechanism may be of particular importance for
highly lipophilic compounds (log Pow > 4), in particular for those that
are poorly soluble in water (≤ 1 mg/L) which would otherwise be poorly
absorbed (ECHA, 2012).
The results of the acute oral toxicity study in rats showed no
evidence of absorption (Lewis, 1977). As the lack of effects may be
based on the absence of absorption or the absence of toxicity of the
substance no final conclusion can be drawn. Based on the low water
solubility, the molecular weight range and the log Pow absorption of the
substance or rather individual components is possible. For the
components with a log Pow of <4 absorption may occur through passive
diffusion, whereas components with a log Pow of >4 may be taken up by
The dermal uptake of liquids and substances in solution is higher
than that of dry particulates, since dry particulates need to dissolve
into the surface moisture of the skin before uptake can begin. Molecular
weights below 100 g/mol favour dermal uptake, while for those above 500
g/mol the molecule may be too large. Dermal uptake is anticipated to be
low, if the water solubility is < 1 mg/L; low to moderate if it is
between 1-100 mg/L; and moderate to high if it is between 100-10000
mg/L. Dermal uptake of substances with a water solubility > 10000 mg/L
(and log Pow < 0) will be low, as the substance may be too hydrophilic
to cross the stratum corneum. Log Pow values in the range of 1 to 4
(values between 2 and 3 are optimal) are favourable for dermal
absorption, in particular if water solubility is high. For substances
with a log Pow above 4, the rate of penetration may be limited by the
rate of transfer between the stratum corneum and the epidermis, but
uptake into the stratum corneum will be high. Log Pow values above 6
reduce the uptake into the stratum corneum and decrease the rate of
transfer from the stratum corneum to the epidermis, thus limiting dermal
absorption (ECHA, 2012).
The physicochemical properties (waxy solid, log Pow and water
solubility) of the substance and the molecular weight are in a range
suggestive of low absorption through the skin. The results of the acute
dermal toxicity study in rats showed no evidence of absorption
(Bradshaw, 2010). As the lack of effects may be based on the absence of
absorption or the absence of toxicity of the substance no final
conclusion can be drawn.
If a substance shows skin irritating or corrosive properties,
damage to the skin surface may enhance penetration. If the substance has
been identified as a skin sensitizer then some uptake must have occurred
although it may only have been a small fraction of the applied dose
For the test substance itself, slight effects regarding to skin
and eye irritation were observed, which could enhance dermal penetration
of the substance. Data on skin sensitisation show that the substance is
not sensitising in a LLNA (Bradshaw, 2010).
Overall, taking all available information into account, the dermal
absorption potential is considered to be rather low.
Lanolin fatty acids is a waxy solid with a vapour pressure of <
700 Pa at 20 °C (experimental data). The vapour pressure was deemed to
be quite high for a solid, and it was suspected that the sample
contained water hence the magnitude of the results. EPI suiteTMcalculated
vapour pressure results in <0.01 Pa (at 25°C). In addition the boiling
point is >320°C indicating that Lanolin fatty acids is not highly
volatile. Therefore, under normal use and handling conditions,
inhalation exposure and thus availability for respiratory absorption of
the substance in the form of vapours, gases, or mists is not significant.
However, the substance may be available for respiratory absorption
in the lung after inhalation of aerosols, if the substance is sprayed
(e.g. as a formulated product). In humans, particles with aerodynamic
diameters below 100 μm have the potential to be inhaled. Particles with
aerodynamic diameters below 50 μm may reach the thoracic region and
those below 15 μm the alveolar region of the respiratory tract (ECHA,
As for oral absorption, the molecular weight, log Pow and water
solubility indicate that absorption via inhalation cannot be excluded,
but is expected to be rather low.
Distribution and accumulation
Distribution of a compound within the body depends on the
physicochemical properties of the substance; especially the molecular
weight, the lipophilic character and the water solubility. In general,
the smaller the molecule, the wider is the distribution. If the molecule
is lipophilic, it is likely to distribute into cells and the
intracellular concentration may be higher than extracellular
concentration, particularly in fatty tissues (ECHA, 2012).
After being absorbed, fatty acids are (re-)esterified along with
other fatty acids into triglycerides and released in chylomicrons into
the lymphatic system. Fatty acids of carbon chain length ≤ 12 may be
transported as the free acid bound to albumin directly to the liver via
the portal vein, instead of being re-esterified. Chylomicrons are
transported in the lymph to the thoracic duct and eventually to the
venous system. Upon contact with the capillaries, enzymatic hydrolysis
of chylomicron triacylglycerol fatty acids by lipoprotein lipase takes
place. Most of the resulting fatty acids are taken up by adipose tissue
and re-esterified into triglycerides for storage. Triacylglycerol fatty
acids are likewise taken up by muscle and oxidized for energy or they
are released into the systemic circulation and returned to the liver
(Lehninger, 1998; Stryer, 1996; WHO, 2001). Stored fatty acids underlie
a continuous turnover as they are permanently metabolised for energy and
excreted as CO2.
Lanolin fatty acids is supposed to be metabolised via the standard
metabolism pathways for fatty acids.
Fatty acids are degraded by mitochondrial β-oxidation which takes
place in the most animal tissues and uses an enzyme complex for a series
of oxidation and hydration reactions resulting in the cleavage of
acetate groups in form of acetyl CoA. The alkyl chain length is thus
reduced by 2 carbon atoms in each β-oxidation cycle. The complete
oxidation of unsaturated fatty acids such as oleic acid requires an
additional isomerisation step. Alternative pathways for oxidation can be
found in the liver (ω-oxidation) and the brain (α-oxidation). Thus
iso-fatty acids such as isooctadecanoic acid have been found to be
activated by acyl coenzyme A synthetase of rat liver homogenates and to
be metabolised to a large extent by ω-oxidation. Each two-carbon unit
resulting from β-oxidation enters the citric acid cycle as acetyl CoA,
through which they are completely oxidized to CO2 (Lehninger, 1998;
The results of the in vitro genotoxicity studies did not show any
evidence that the addition of the metabolic system either enhances or
diminishes the activity of the substance (Bowles & Thompson, 2010;
Bowles, 2010; Brown, 2010).
In general, fatty acids are catabolised entirely by oxidative
physiologic pathways ultimately leading to the production of carbon
dioxide and water. Small amounts of ketone bodies resulting from the
oxidation of fatty acids are excreted via the urine (Lehninger, 1998;
Stryer, 1996). Unmetabolised Lanolin fatty acids that may be absorbed is
supposed to be excreted in the bile and thus excreted via the faeces, as
poorly water-soluble products are not favourable for urinary excretion.
Any test material that is not absorbed will be excreted in the faeces.
The available information showed some evidence that Lanolin fatty
acids, is expected to be absorbed via the gastro-intestinal tract. Once
absorbed, the substance may be distributed systemically and temporarily
stored in the adipose tissue. The substance is supposed to be
metabolised within the standard metabolic pathways for fatty acids
resulting in complete oxidation to CO2. Biliary excretion may well be a
significant route of excretion for the unmetabolised part of the
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.
Tällä verkkosivustolla käytetään evästeitä parhaan mahdollisen käyttäjäkokemuksen varmistamiseksi.
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