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EC number: 941-809-7
CAS number: -
There are no studies available in which the toxicokinetic behaviour of
Sophorolipids, partially hydrolysed, has been investigated.
Therefore, in accordance with Guidance on information requirements and
chemical safety assessment Chapter R.7c: Endpoint specific guidance
(ECHA, 2014), assessment of the toxicokinetic behaviour of Sophorolipids
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 physico-chemical and toxicological
properties according to Guidance on information requirements and
chemical safety assessment.
> 600 g/mol. Recently used batch for testing: 637 g/mol (according to the manufacturer)
150 °C, decomposition
Not applicable; decomposition
1.1E-17 Pa (QSAR)
Partition coefficient n-octanol / water (logKow)
147 g/L (filtrated)
0.2 – 0.4 g/L
Solubility in organic solvents
3 – 5 g/L
Handled only in solution
Chapter R.7c: Endpoint specific guidance (ECHA, 2008)
The components of this UVCB substance consist of two sugar units
(sophorose) bearing a fatty acid chain (which is derived from C18
unsaturated fatty acids with different degree of unsaturation), both as
lactone form and as acidic form. Some of the free hydroxyl-groups of the
sugar units are acetylated.
Sophorolipids are solid at room temperature and have a molecular weight
of ca. 637 g/mol according to the information given for a recent batch.
Besides, the test item is handled only in solutions.
The measured water solubility of the filtrated test item was 147 g/L,
while the critical micelle concentration (CMC) was 0.2 to 0.4 g/L.
Solubility in organic solvents was 3 – 5 g/L.
The logKow has been calculated to be 2.4. This
calculation has been derived from the measurements of CMC and solubility
in octanol as a worst case LogKow value.
The substance possesses surface activity. The determined value was 37.3
The vapour pressure is calculated to be 1.1E-17 Pa at
In general, molecular weights below 500 are favourable for oral
absorption while molecular weights above 1000 do not favour absorption
(ECHA, 2014). As the average molecular weight of Sophorolipids is >600
g/mol, absorption of the molecule in the gastrointestinal tract
according to molecular weight is thought to be reduced but may still
occur to a relevant extent. Also, the logKow of 2.4 is in a range
suggestive of absorption from the gastro-intestinal tract subsequent to
oral ingestion (log Kow between -1 and 4).
Overall, a systemic bioavailability of Sophorolipids and/or the
respective cleavage products in humans is considered likely after oral
uptake of the substance. For chemical safety assessment an oral
absorption rate of 50 % is assumed as a worst-case default value in the
absence of other data.
The smaller the molecule, the more easily it may be taken up. In
general, a molecular weight below 100 favours dermal absorption, above
500 the molecule may be too large (ECHA, 2014). The molecular weight of
Sophorolipids is >600g/mol is thus not favourable for dermal absorption.
Besides, logKow values between 1 and 4 favour dermal absorption (values
between 2 and 3 are optimal) particularly if water solubility is high.
The logKow of 2.4 as a worst-case assumption may in this case favour
dermal absorption, while the molecular weight of >600 g/mol, as stated
above, may not.
If the substance is a skin irritant or corrosive, damage to the skin
surface may enhance penetration (ECHA, 2014). As Sophorolipids are not
skin irritating in humans, enhanced penetration of the substance due to
local skin damage is not expected.
For chemical safety assessment a dermal absorption rate of 50 % is
assumed as a worst-case default value in the absence of other data.
For chemical safety assessment an inhalation absorption rate of 100 % is
assumed as a worst-case default value in the absence of other data.
Distribution, Metabolism and Excretion
Distribution within the body through the circulatory system depends on
the molecular weight, the lipophilic character and water solubility of a
substance. 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, 2014).
Besides, the test substance is most likely rapidly degraded after uptake
and thus, the characteristics of the parent compound do not apply. The
sugar units and the fatty acids resulting from breakdown are thought to
be absorbed and metabolized rather rapidly.After[JF1] oral
ingestion, esters of short-chain (C2-8) alcohols and fatty acids undergo
stepwise chemical changes in the gastro-intestinal fluids as a result of
hydrolysis. This firstly leads to the acidic form of Sophorolipids.
Therefore, the lactone form of the Sophorolipid will be hydrolysed and
will result in the acidic form. The test substance, once the acid form
is prevalent after oral ingestion, is likely to undergo further
breakdown in the GI tract. According to the publication by Saghir et al.
(1997), fatty acid ethyl esters are very rapidly and extensively
hydrolysed in the GI tract at the level of the duodenum and in the
blood. Guidance R.7c states that when the physico-chemical
characteristics of the further cleavage products (e.g. physical form,
water solubility, molecular weight, log Pow, vapour pressure, etc.) are
likely to be different from those of the parent substance before
absorption into the blood takes place, the predictions based upon the
physico-chemical characteristics of the parent substance do no longer
apply (ECHA, 2014). However, also for the cleavage products, it is
anticipated that they are absorbed in the gastro-intestinal tract. The
highly lipophilic fatty acid is absorbed by micellar solubilisation
(Ramirez et al., 2001), whereas the sugar units are readily dissolved
into the gastrointestinal fluids and absorbed from the gastrointestinal
tract. The metabolic fate of the fatty acids derived from hydrolysis
then depends on the organ or tissue into which it is incorporated.
Besides, the further metabolic fate of the fatty acids is considered
irrelevant in terms of toxicokinetic assessment as they do structurally
not differ from those derived from nutritional fat.
For Sophorolipids, the main route of excretion is expected to be by
expired air as CO2after metabolic degradation. The second
route of excretion is expected to be by biliary excretion with the
faeces. For the cleavage products, the main routes are renal excretion
via the urine and exhalation as CO2.
Based on the available data no additional conclusions can be drawn on
the distribution, metabolism and excretion of Sophorolipids.
Due to the lack of experimental data, 100 % absorption by inhalation and
50 % absorption via the oral and dermal route is assumed as worst case
default for chemical safety assessment.
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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