Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Link to relevant study record(s)

Description of key information

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

No toxicokinetic data on the registered substance is submitted. Absorption of the notified chemical through the skin and gastrointestinal tract is expected to be limited by its low partition coefficient (<-4.18 and -1.48 for the inorganic and organic components, respectively), though its moderate water solubility (0.225 g/l and 0.150 g/l for the organic and inorganic components, respectively) and relatively low molecular weight (< 500 Da) suggest that some absorption may occur. This is supported by the systemic toxicity in the 28-day oral study and OECD 422 study with MPP in rats where effects in the kidneys were noted. Pyrophosphate once absorbed will be likely to behave like diet phosphorus and therefore assimilated or excreted but not accumulating.


Inhalation of powders of the notified chemical may occur, given that it contains ~76% of particles of inhalable size. However, respiration of the notified chemical is not expected to be significant, given that only a small proportion is of respirable size (0.7%). Upon deposition in the airways, due to its moderate water solubility, the notified chemical may dissolve/diffuse into the mucus lining the respiratory tract and subsequently be transported out of the respiratory tract. This also suggests that the notified chemical may be systemically absorbed following inhalation.


It is possible that the MPP shows different physico-chemical properties from the organic component of MPP (melamine) and pyrophosphate because MPP is not inorganic salt of melamine or pyrophosphate but organic salt constituted by both of them. And according to these differences, it may also show different environmental and metabolic pathway from melamine and pyrophosphate.