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EC number: 500-078-0
CAS number: 31923-84-9
1 - 4.5 moles propoxylated
ETHANE-1,2-DIOL, PROPOXYLATED, 1-4.5 MOL PROPOXYLATED (CAS31923-84-9; EU
NLP 500-078-0) AND 2,2’-OXYDIETHANOL, PROPOXYLATED, 1-4.5 MOL
PROPOXYLATED (CAS9051-51-8; EU NLP 500-031-4)
These two core substances are so closely related structurally that they
are best examined together.
There are no experimental studies on the toxicokinetics of propoxylated
ethane-1,2-diol or propoxylated 2,2’-oxydiethanol. The toxicokinetics of
the core substances and the repeating unit are summarised in Illing and
Barratt (2007 revised 2009). Both core substances have two free hydroxy
groups, thus NLP polyols are likely to consist predominantly of chains
of between one and two repeating units, with some chains containing
three repeating units.
For the calculations of bioavailability of the commercial NLP polyol,
logP values were calculated using the incremental fragment method of
Suzuki and Kudo (1990). The propoxy groups have an important effect on
the toxicity by modulating any toxicity arising from the core
substance. The substitution of a hydroxyl group on a core compound by a
propoxy group increases its logP value by 0.24 units and its molecular
weight by 58Daltons. The combined effect of these changes is to reduce
the bioavailability by a factor of 1.53 (calculated using the Potts and
Guy equation). MEG + 3PO indicates the component representing the mean
Given the vapour pressure and water solubility of the commercial
preparation, it is likely that absorption of some of the lower molecular
weight components may occur via the lung.
Ethane1,2-diol, oxydiethanol, 2,2’-(ethylenedioxy)diethanol,
propane-1,2-diol, oxydipropanol and
[(methylethylene)bis(oxy)]dipropanol are absorbed, probably by passive
diffusion, when administered orally. Thus it is probable that low number
oligomers will be absorbed. The calculated logP suggests that the
component representing the mean toxicity of the commercial preparation
is likely to be absorbed orally.
Given the logP values, it is likely that any absorbed oligomers of
propoxylated etahne-1,2-diol or 2,2’-oxydiethanol will be widely
distributed in the body. As metabolism is likely, it is unlikely that
they will accumulate in tissues.
In the event that higher molecular weight material is absorbed, it is
likely to be excreted in bile. Lower molecular weight unmetabolised
oligomer is likely to be excreted in urine. In rat the molecular weight
threshold for biliary excretion is around 350, in human it is about 500
(Illing, 1989). The material most likely to be absorbed is likely to be
hydrolysed and the products appear in urine. Some carbon dioxide might
be formed from hydrolysis of the propane-1,2-diol groups and exhaled.
Based on information from ethane-1,2-diol, oxydiethanol, and
(ethylenedioxy)diethanol, propane-1,2-diol, oxydipropanol and
[(methylethylene)bis(oxy)]dipropanol it is likely some material may be
hydrolysed, some oxidation of one or both of the terminal alcohol groups
to the corresponding mono and di-carboxylic acids may occure or,
possibly some conjugation of the terminal alcohol groups with glucuronic
acid and/or sulphate may also be possible. At low doses some further
metabolism to carbon dioxide may occur.
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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