Neurotoxicology
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Methylcyclopentadienyl Manganese Tricarbonyl (MMT) has been used since the 1970s in the U. S. as a gasoline octane enhancer Extensive testing of the effects of MMT on regulated gaseous emissions carried out on a wide variety of automobiles showed that use of MMT resulted in significantly lower NOx emissions Tests showed that less than 15% of the manganese from MMT combustion was emitted from the tailpipe, mostly in the PM2.5 fraction as manganese phosphate, with some manganese sulfate and a very small amount of manganese oxide. MMT has been used in Canada in virtually all unleaded gasoline for about 20 years. ⋯ Exposures to manganese among the general population in Toronto are well within safe limits determined by the U. S. EPA and other standard setting bodies around the world.
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In 1994, the U. S. Environmental Protection Agency (EPA) denied a petition by Ethyl Corporation to allow the use of methylcyclopentadienyl manganese tricarbonyl (MMT) in unleaded gasoline, because of health concerns related to the inhalation of manganese (Mn) particulate emissions from combusted MMT. ⋯ To improve the risk characterization, better information on Mn/MMT population exposures and health effects is needed. Much of this information is expected to be obtained under provisions of Section 211 of the Clean Air Act. Among the specific issues that remain to be resolved are the form or forms of Mn emitted from the combustion of MMT in gasoline and the potentially different toxic properties of Mn in different forms.