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EC number: 905-806-4
CAS number: -
Due to the high reactivity of the substances of the MDI category with water, bioaccumulation tests can in principle not be performed with these substances. However, one bioaccumulation test (OECD 305E) with 4,4'-MDI (CERI, 2000) and a mesocosm study with PMDI with an indication of bioaccumulation potential have been performed (Heimbach, 1993). As no analytical measurements were done, it cannot be determined if the values are truely related to MDI. However, based on the available information and the reactivity of MDI substances of the category approach, no new bioaccumulation study is deemed necessary.
The test substance is covered by the category approach of
methylenediphenyl diisocyanates (MDI). Hence, data of the category
substances can be used to cover this endpoint. It is recognised that
there is a measured log Pow value of 4.51 for monomeric MDI (determined
with MDI mixed isomers) (Yakabe et al., 2000). This log Pow value is
only of theoretical interest as MDI is very unstable in aqueous media
(hydrolysis half-life T1/2 = 20h), see Section 5.1.2: Hydrolysis). The
determination was by an HPLC method and comparison to reference
A BCF study (CERI, 2002) carried out according to guideline principles
with [14C] radiolabelled 4,4’-MDI and Cyprinus carpio,
derives BCF values of 92 and 200 for concentrations of 0.8 and 0.08 µg
MDI/L. The reported BCF values are highly questionable given the known
rapid hydrolysis of MDI under these conditions. Liquid scintillation
counting was the method of analysis for all water and fish samples and
no analyses of 4,4’-MDI itself were carried out during the course of the
study. A BCF value of 200 indicates low potential for bioaccumulation,
but it must be recognised that this value probably reflects the
bioconcentration of water soluble hydrolysis products which most likely
include 4,4’-MDA and low molecular weight ureas. So it can be concluded
that degradation products of MDI do not bioaccumulate.
MDI reacts with water to form predominantly high molecular weight, inert
polyureas and trace amounts of 4,4’-methylenedianiline (MDA). This MDA
is considered as the only degradation product of significance, and it
has a log Pow value of 1.55. Its measured BCF is < 14 (at 0.2 mg/L) in Cyprinus
carpio (EU Risk Assessment Report: 4,4’-methylenedianiline, 2001).
So, it is concluded that degradation products of MDI do not
There is a mesocosm study on PMDI (Heimbach 1993, PMDI dossier 6.1.2a)
study, carried out over 112 days, at a loading of 10,000 mg PMDI/L. MDI
was detected neither in the water (detection limit 0.005 mg/L) nor in
fish (detection limit 0.51 mg/kg). A numeric BCF can not be calculated
from these non-detects, but clearly these results show in a practical
way that MDI does not accumulate in fish.
Lastly, a BCF value of 439 for 4,4’-MDI may be estimated using the BCFBAFTM
(v 3.00) model, a part of the Estimation Program Interface Suite
(v.4.00, 2009) of QSAR tools (Tury, 2010). An estimated BCF value of 439
for 4,4’-MDI suggests a low potential for bioaccumulation. This is in
line with the low bioaccumulation value found in the bioaccumulation
study and in the mesocosm study.
To summarise, a new bioaccumulation study is not deemed necessary due to
rapid hydrolysis (resulting in unlikely exposure) of substance of the
MDI category. Supporting data including a mesocosm study, modelling and
assessment of degradation products, all indicate no potential for
significant bioaccumulation in the aquatic environment.
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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