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EC number: 923-201-3
CAS number: -
The bioaccumulation potential is expected to be low.
UMA 121 is the reaction product of the following substances:
Methylendiphenyldiisocyanate, isomer mixture of 4,4’- and 4,2’-MDI
(MDI) CAS No. 26447-40-5
Dipropylene glycol (DPG) CAS No. 25265-71-8
2-hydroxypropylmethacrylate (HPMA) CAS No. 27813-02-1
The reaction product is a solid resin containing the polymer
HPMA-MDI-(DPG-MDI)n-HPMA as homologues of n = 0, 1, 2, 3, etc. (no upper
limit defined) as well as free HPMA.
The water solubility of UMA 121 was determined to be 0.4 mg/L in
an OECD 105 study. However, taking into account that the water
solubility is 130 g/L for HPMA (ECHA website, Registered substances) and
0.0002 - 0.002 mg/L for the shortest UMA homologue (n=0) (WSKOW v1.42
and WATERNT v1.01), it can be assumed that the 0.4 mg/L solubility is
mainly due to HPMA and that the dissolution of UMA homologues is
Release of UMA 121 to surface waters is unlikely, as it will be
removed in sewage treatment plants to a high extent. As stated in the
“Guidance on information requirements and chemical safety assessment
Chapter R.7b: Endpoint specific guidance”, insoluble chemicals will be
removed in the primary settling tank or fat trap of sewage treatment
plants (ECHA, 2012). Possible remaining amounts would be adsorbed adsorb
to the activated sludge. However, as discussed above HPMA is far more
soluble than the rest of the constituents. It might thus dissolve into
the water phase. But due to its ready biodegradability it would most
likely be removed though biodegradation by the activated sludge (ECHA
website, Registered substances).
If UMA homologues were to be present in natural waters, their
uptake by organisms is considered unlikely. The smallest homologue
HPMA-MDI-HPMA (n=0) has a molecular weight of 538.60 g/mol. For the
larger homologues (n≥1) molecular weights are above 900 g/mol. All
homologues have log Kow values above 5 (KOWWIN v1.68). These
constituents are therefore unlikely to cross biological membranes.
According to Lipinski’s “rule of 5”, developed to identify drug
candidates with poor oral absorption, a molecular weight > 500 g/mol and
a log Kow > 5 indicate a low potential of absorption after oral uptake
(Lipinski, 1997). Furthermore, a Combined Repeated Dose Toxicity Study
with the Reproduction / Developmental Toxicity Screening Test (OECD 422)
conducted with UMA 121 did not reveal any test substance-related effect
(Takawale, 2013). As stated in the “Guidance on information requirements
and chemical safety assessment Chapter R.11: PBT Assessment”, the
complete absence of effects in mammalian long-term studies is an
indication that the compound is either chronically non-toxic and/or that
it is not taken up to a significant extent.
Finally, as UMA 121 is poorly soluble and consists of an unknown
amount of different homologues (n = 0, 1, 2, 3, etc.) it would be
problematic to obtain meaningful results from a standard bioaccumulation
study, due to analytical difficulties.
In conclusion, the exposure of aquatic organisms to UMA 121 is
expected to be minimal, due to the low solubility of the UMA homologues.
In the unlikely event of exposure, uptake of UMA 121 by organisms is
considered unlikely, based on the high molecular weight of the UMA
homologues. The HPMA constituent, which might be released, is expected
to have low bioaccumulation potential, due to its low log Kow value.
Based on the available information, UMA 121 can be assumed to have low
Lipinski CA, Lombardo F, Dominy BW, and Feeney PJ. 1997.
Experimental and computational approaches to estimate solubility and
permeability in drug discovery and development settings. Adv.Drug
Deliv.Rev. 23: 3-25
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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