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EC number: 201-063-9
CAS number: 77-85-0
Trimethylolethane is a low molecular weight
(MW = 120.15) substance and is a solid at room temperature with a
melting point of 198°C. It is very soluble in water with a solubility of
350 g/l at 20 °C and it has a log Pow is -1.26 at 20°C which indicates
that the substance will lack solubility in lipids.
In its solid form Trimethylolethane is a
granular powder. Particle size analysis found that 23.8% of the
particles are inhalable (particle size <100 µm) and that 5.45% were <
5.5 µm and therefore classed as potentially respirable particles.
Trimethylolethane is hydrolytically stable
with an estimated half-life of > 1 year at 25 °C at pH 4, pH 7 and pH 9.
No ready biodegradability test has been conducted on Trimethylolethane;
however, by read-across to Trimethylolpropane it is considered that it
will not be readily biodegradable.
Trimethylolethane in solid form contains <
23.8% particles that could be inhaled following exposure to airborne
dusts. Much of this dose can be expected to be transferred to the
stomach via mucocilliary action and swallowing; however, 5.45% of
particles are < 5.5 µm and can be classified as respirable and if
inhaled could reach the alveoli where absorption directly into the blood
stream could take place.
Trimethylolethane is a low molecular weight
molecule and therefore its size is unlikely to present a significant
barrier to absorption across the gastrointestinal mucosa, hence, uptake
as it passes through the gastrointestinal tract may occur. However,
uptake is likely to be limited as Trimethylolethane has a log P value of
-1.26 at 20°C and therefore the non-ionised form is unlikely to have
sufficient lipid solubility to easily pass across biological membranes.
It is unlikely that active transport mechanisms will be a significant
uptake route due to a lack of similarity with endogenous molecules.
Overall, it can be expected that absorption
of the intact molecule across the gastrointestinal mucosa will occur,
but a proportion of an oral dose is likely to not be absorbed and
subsequently be excreted in the faeces.
An oral repeated dose reproductive toxicity
with developmental toxicity screening study (OECD 422) has been
conducted on a read-across substance Trimethylolpropane using doses of
12.5, 50, 200 and 800 mg/kg/bw/day. No effects on reproductive
performance were observed during the study. General toxicity effects
observed which were attributable to test item were a reduction in body
weight in both males and females and in male’s significant increases in
absolute liver weight with some histopathological changes. The study
NOAEL for general toxicity was 200 mg/kg bw/day. The results indicate
that Trimethylolpropane was absorbed and it, and/or its metabolites were
at a sufficient concentration to exert effects. Based on these results
it is expected that given its structural similarity, Trimethylolethane
will be absorbed and have a similar profile following repeat dosing.
Trimethylolethane is a small molecule (MW
120.15) and given its molecular weight it is conceivable that a dermal
absorption could occur. In an acute dermal toxicity study on the
read-cross substance, Trimethylolpropane, there was evidence of
absorption following dermal exposure as histopathological changes
occurred in the kidneys from a dose of 2150 mg/kg bw (study top dose
10,000 mg/kg bw). It is expected that Trimethylolethane will show a
similar dermal absorption profile.
It is unlikely that Trimethylolethane will
exhibit any significant distribution within the body between plasma and
tissues as its log P value (-1.26) does not indicate it will have a
strong affinity for fats.
Because no reproductive effects were
observed for the read-across substance, Trimethylolpropane, it is not
possible draw any conclusions about whether the distribution of
Trimethylolethane in the body could include the reproductive organs.
Trimethylolethane contains water
solubilising hydroxyl groups which are likely to aid excretion and also
metabolism of the molecule by cytochrome P450 enzyme metabolising
system. Hence, in organisms such as mammals and fish with significantly
developed xenobiotic metabolising systems, Trimethylolethane is expected
to undergo a degree of metabolism resulting in breakdown of the molecule
and ultimate excretion.
In two in vitro bacterial Ames assays, an in
vitro mammalian chromosome aberration assay in Chinese Hamster Ovary
cells and an in vitro gene mutation assay in Chinese Hamster Fibroblasts
cells on the read-across substance Trimethylolpropane, gave negative
results in both the presence and absence of an S9 metabolising system.
Given the negative results, no conclusions about the potential of
Trimethylolpropane and concomitantly Trimethylolethane ethane to undergo
metabolic change can be drawn from these studies.
Due to presence of water solubilising groups
present on Trimethylolethane, or added during metabolism, the main route
of excretion of absorbed Trimethylolethane and/or its metabolites is
likely to be via the kidneys into the urine.
In an acute dermal toxicity study on the
read-across substance Trimethylolpropane, histopathological changes were
observed in the kidneys suggesting that either Trimethylolpropane and/or
its metabolites were excreted via the kidneys. It is expected that
Trimethylolethane will have a similar profile.
The molecular weight of Trimethylolethane is
below the biliary exclusion limit of circa 325 in the rat and 500 in
humans and therefore elimination of any absorbed substance in the bile
is not expected to be significant.
An expert review of the toxicokinetic
profile of Trimethylolethane was undertaken based on its
physico-chemical profile and available data from toxicological studies
on a read-cross substance.
Observations from an acute dermal toxicity
study on the read-across substance Trimethylolpropane, indicate it can
be absorbed through the skin and it is expected that Trimethylolethane
will similarly be able to penetrate the skin.
In the case of the gastrointestinal system,
absorption is likely to be slow and most of an oral dose is expected to
be excreted in the faeces. However, a proportion will be systemically
absorbed as demonstrated by the observation of treatment related effects
in a repeat dose toxicity with reproductive developmental toxicity
screening study (OECD 422) conducted on the read-across substance
The presence of hydroxyl groups on the
structure can be expected to aid metabolism of systemically, absorbed
Trimethylolethane to water soluble products that will ultimately be
excreted via the kidneys.
There is no expectation that
Trimethylolethane will preferentially distribute to particular organs or
tissues in the body.
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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