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EC number: 941-496-7
CAS number: 1689576-89-3
Table 1: Individual draize scores in the left eye of rabbits (not rinsed)
DRAIZE grade after
Mean of 6 animals (24-48-72 h)
Conj. = 0.61
Che. = 0.56
Conj.: conjuctivae; Che.:Chemosis
No eye irritation data exist for the target substance 44MDI/1,3-BD/TPG/PG. This endpoint is satisfied by weight of evidence and read across from six valid eye irritation studies performed with 4,4’-MDI, 2,2’-MDI, MDI mixed isomers, pMDI, MDI Mixed Isomers/PIR and 4,4’-MDI/TPG, all belonging to the MDI category. All of the available studies are assigned Klimisch ratings of either 1 or 2.
All substances of the MDI category share similar chemical features namely that they a) all contain a significant amount of mMDI, and b) contain at least two NCO functional groups per molecule which are bound to an aromatic ring, and this ring is connected to a second aromatic ring by a methylene group. It is the NCO value (driven by the low molecular weight bioaccessible groups on monomeric MDI and three-ring oligomer) which is responsible for chemical and physiological reactivity and subsequent toxicological profile. As mentioned above, all substances of the MDI category contain a high content of monomeric MDI. This is key to the hypothesised MoA for all substances of the MDI category.
Since it has been demonstrated that NCO value (as attenuated by solubility) is responsible for toxicity and the higher molecular weight, low solubility components do not contribute to the observed toxicity, it is reasonable to assume that their presence in these mixtures diminishes the overall toxicity causing variation in effect. However, as all substances contain sufficient bioaccessible MDI constituents to elicit effects, a worst-case approach is adopted in which the most bioaccessible substances are read across to all substances of the MDI category. Therefore, the harmonized CLP classification as eye irritant category 2 (H319) for 4,4’-MDI is adopted for all category substances, including 44MDI/1,3-BD/TPG/PG.
For more details see category justification document attached in IUCLID section 13.
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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