Manganese effect

Roels H, Lauwerys R, Buchet J-P, et al Epidemiological survey among workers exposed to manganese effects on lung, central nervous system, and some biological indices. Am J Ind Med 11 307-327,1987... 

Siqueira and Moraes 1989). However, the relationship between manganese effects on peripheral versus central dopamine levels has not been clearly defined, and given the lack of change in dopamine content in substantia nigra of humans exposed to manganese, the relevance of the animal studies to central nervous system disorder is questionable. 

Effect. No reliable biomarkers of manganese effect are known. Biochemical changes such as altered blood or urinary levels of steroids, neurotransmitters, or their metabolites are plausible biomarkers of exposure, but this possibility has not been thoroughly investigated. Although methods exist for the analysis of these biochemicals, further work to improve the analyses does not seem warranted unless the utility of this approach is established. 

A similar terpyridine based chelate is marketed (Perkin-Elmer) as Eu-W8044 DTA chelate 4 and has a dichlorotriazinyl group as a reactive arm [39]. Again the nonadentate complexation increases the stability, the fluorescence is stable at pH 5 and decreases by 20% within 2 h incubation in 50 mM succinate pH 4, but 90% of the fluorescence is lost at pH 3 (the difference of behavior with the Eu-TMT vide supra could be due to the difference in buffer composition). The Eu-W8044 is also more stable in the presence of EOT A and can withstand 2 h in 250 mM EDTA pH 7.8, but manganese effect is still detrimental since 80% of the fluorescence is lost within 30 min in the presence of 100 pM Mn " as described above for the heptadentate Eu-W 1024 chelate, a calculated amount of EDTA cancels the manganese effect (www.perkinelmer.com/lifesciences, Stability of the Wallac LANCE Eu-chelates ). 

The inhibition by copper salts, first reported by Swedin and Theorell in 1940, shows some similarity to the manganese effect. For, according to Yamazaki et al. (1956), while under optimal pH conditions copper inhibits, in more alkaline media, where the effect of manganese becomes marked, copper becomes stimulatory to the oxidase reaction. It is even more effective than manganese in these circumstances. Cobalt is also stimulatory above pH 7, although it does inhibit below this pH while ferrous salts, inhibitory in the acid range, are neither inhibitory nor stimulatory in neutral and alkaline media. 

Acrylamide copolymers are effective iron ore pellet binders (118). When the ore slurry in water has a pH above 8, anionic polymers are effective. If the ore is acid washed to remove manganese, then a cationic polymer is effective. 

In 1957, Ethyl Corp. announced anew antiknock compound, methylcyclopentadienyknanganese tricarbonyl [12108-13-3] (MMT). MMT is almost as effective as lead on a per gram of metal basis, but because manganese was more expensive than lead, MMT was not widely used until limits were placed on the lead content of gasoline. MMT was used in unleaded fuel between 1975 and 1978. After a large fleet test suggested that MMT could increase exhaust emissions because it interfered with catalysts and oxygen sensors, EPA banned its use in unleaded fuel in 1978. MMT is used in Canada in unleaded fuel. 

Reactions 33 and 35 constitute the two principal reactions of alkyl hydroperoxides with metal complexes and are the most common pathway for catalysis of LPOs (2). Both manganese and cobalt are especially effective in these reactions. There is extensive evidence that the oxidation of intermediate ketones is enhanced by a manganese catalyst, probably through an enol mechanism (34,96,183—185). 

Health and Environment. Manganese in trace amounts is an essential element for both plants and animals and is among the trace elements least toxic to mammals including humans. Exposure to abnormally high concentrations of manganese, particulady in the form of dust and fumes, is, however, known to have resulted in adverse effects to humans (36,37) (see Mineral nutrients). 

Medical and Biologic Effects of Environmental Pollutants-Manganese, Division of Medical Sciences, National Research Council, National Academy of Sciences, 1973. 

Human and animal studies indicate that inorganic manganese compounds have a very low acute toxicity by any route of exposure. The toxicity values for a given Mn compound are shown in Table 20 to depend on the species of test animal as well as the route of exposure. Manganese concentrations as high as 2000 ppm were found to be tolerated by test animals over a six-month period without any ill effects (208). 

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