MANGANESE IN DRINKING-WATER AND ITS CONTR IBUTION ON HUMAN EXPOSURE

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used in Ca nada since 1976 as an additive in unleaded gasoline. The combustion of MMT leads to the emission of Mn oxides to the environment and may rep resent a potential risk to public health. It therefore seems important to assess the associated Mn exposure. The present study is part of a broader research program on total human exposure to Mn and aims specif ically at assessing the level of exposure to Mn and other metals via d rinking water. A comparative study was performed between two groups of workers (garage mechanics and blue collar workers of the University o f Montreal) differentiated by their exposure to inhaled Mn. For Pb, Cu and Zn in residential tap water, significant differences were observe d between the first sample and the one taken after one minute of flow. A significant difference was also found between the two groups of wor kers (combined flow time) for Mn, Cu and Ca. The Mn contribution from water is estimated to be 1 % of the total dose from ingested food. Thi s low exposure may become important (17 %) for persons drinking well w ater, especially if we consider interactions between metals following multimedia exposure.