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Description of key information

Short description of key information on bioaccumulation potential result: 
MPA is predicted to be moderately bioavailable (50%) via the oral route and readily absorbed via skin.
MPA is expected to undergo stepwise oxidation of the thiol group and also disulphide bridge formation with cysteine or with another MPA molecule. MPA and its metabolites are very polar and thus subject to renal elimination. Tissue accumulation can be excluded.

Key value for chemical safety assessment

Additional information

Absorption

Oral absorption of MPA is predicted to be moderate. The Danish QSAR database predicts an oral absorption of 50% following a dose of 1 mg.

The Danish QSAR database predicts a high dermal absorption of 0.089 mg/cm²/event. It is noteworthy that MPA is highly corrosive, so that contact with skin must be thoroughly prevented. 

Distribution

MPA and its predicted oxidation products are very polar and are predicted to have no accumulation potential. They are expected to enter the urine shortly after systemic absorption.

Metabolism

MPA will undergo enzymatic and non-enzymatic ester oxidation of its thiol group. This is a stepwise process. It is predicted that MPA can also be oxidised to form disulphide bridges either with itself (dimerisation) or with cysteine, either in glutathione or in proteins. The latter process may promote skin sensitisation.