American journal of industrial medicine
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Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese (Mn) used in Canadian gasoline since 1976 as an antiknock agent and to improve octane rating. Combustion products of MMT are mainly a mixture of Mn phosphate and Mn sulfate. In 1997, the Canadian federal government adopted a law (C-29) which banned both the interprovincial trade and the importation for commercial purposes of manganese-based substances, including MMT. However, the government reworded this law in July 1998 so that manganese-based fuel additives were not included in the restrictions. MMT is now approved for use in Argentina, Australia, Bulgaria, the United States, France, Russia, and conditionally in New Zealand. Nevertheless, these countries are not using MMT intensively and they are waiting for strong evidence of the absence of effects on human health. Even after several years of use of MMT in Canada, many uncertainties remain. ⋯ Obviously, there is still an important lack of adequate toxicological information and further studies are needed to provide successful implementation of evidence-based risk assessment approaches.