Toxno Substance Profile
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Substance Name

Methylcyclopentadienyl manganese tricarbonyl
Identification Number: CASRN | 12108-13-3

  Substance Attributes


  • Metabolic Interference or Disruption

    Interferes with human metabolism. This can be a very serious thing. Some of these interference mechanics are well established. However, often long term effects and health consequences remain largely unknown. Additionally an emerging area of concern and one that is not currently studied, is the combined synergistic effects these metabolically disrupting chemicals have on human health.


    Metabolic interference happens when the substance produces highly reactive and often damaging intermediates during detoxification or when the substance binds to specific enzymes, important structural groups on molecules, receptors and membranes or targets DNA or mimics key nutrients.

  • Exposure Produces Health Symptoms

    Symptoms maybe short term or long term depending on the exposure duration and intensity and effects areas like Cardiovascular, Gastrointestinal, Cognition, Fatigue. A substance with this attribute may cause an allergic skin reaction, serious eye irritation, allergy or asthma symptoms or breathing difficulties if inhaled.

  • Serious Acute Effects

    This is a serious nasty substance. Effects are Acute (seen immediately). Substances in this category may be FATAL or acutely toxic if inhaled, skin contact or swallowed. See further details.

  • Toxic to specific organs

    Can damage liver, kidney, lungs, heart or gut. Ironically liver, kidneys and gut are the main detoxifications systems.

  • Toxic to Wildlife

    May kill plants, fish, birds or other animals and insects or may be very toxic to aquatic life with long lasting effects. This then effects delicate environmental ecology and food supply in ways we don't fully understand yet.

These attributes are ONLY based on peer-reviewed evidence. See link to Data Sources below. Everyone benefits from knowing this stuff. Please Share.



  • CATEGORIES: Household Toxin | Pollutant | Airborne Pollutant | Food Toxin | Synthetic Toxin | A Hazardous Substance that may be found in the Australian Workplace
  • SUBSTANCE LINEAGE: Inorganic Compounds | Mixed Metal/Non-metal Compounds | Transition Metal Salts | | Pyridoxamines
  • SYNONYMS: (1-Methyl-2,4-cyclopentadien-1-yl)manganese tricarbonyl | (methylcyclopentadienyl)manganese tricarbonyl | (methylcyclopentadienyl)tricarbonylmanganese | 2-(Methylcyclopentadienyl)manganesetricarbonyl | 2-Methylcyclopentadienyl manganese tricarbonyl | 2-Methylcyclopentadienylmanganese tricarbonyl | Antiknock-33 | Combustion improver -2 | Manganese methyl cyclopentadienyl tricarbonyl | Manganese | tricarbonyl methylcyclopentadienyl | Manganese | tricarbonyl(methyl-pi-cyclopentadienyl)- (8CI) | Manganese | tricarbonylmethylcyclopentadienyl | Manganese | tricarbonyl[(1,2,3,4,5-.eta.)-1-methyl-2,4 | Methyl cyclopentadienyl manganese tricarbonyl | Methylcyklopentadientrikarbonylmanganium | Methylcymantrene | MMT | Pi-(methylcyclopentadienyl)manganese tricarbonyl | Pi-methylcyclopentadienylmanganese tricarbonyl | Tricarbonyl(2-methylcyclopentadienyl)manganese | Tricarbonyl(eta(5)-methylcyclopentadienyl)manganese | Tricarbonyl(methylcyclopentadienyl)manganese
  • DESCRIPTION: Methylcyclopentadienyl manganese tricarbonyl (MMT) is a chemical compound of manganese. It was initially used as a supplement to the gasoline additive tetraethyl lead to increase a fuel's octane rating, then later also used in unleaded gasoline. It has been banned in various countries in the past due to its toxicity, but is available in most places today, despite controvery over its safety. Manganese is a naturally occurring metal with the symbol Mn and the atomic number 25. It does not occur naturally in its pure form, but is found in many types of rocks in combination with other substances such as oxygen, sulfur, or chlorine. Manganese occurs naturally in most foods and small amounts are needed to stay healthy, as manganese ions act as cofactors for a number of enzymes. (L228, L229, L239)
  • COMMENTS:

    From Safe Work Australia and the Hazardous Substances Information System (HSIS) in Australia:

    Fatal if swallowed. Fatal in contact with skin. Fatal if inhaled. Causes damage to organs through prolonged or repeated exposure via inhalation. Very toxic to aquatic life with long lasting effects | Chronic Health Hazard Environmental Hazard Acutely Toxic | A Hazardous Substance that may be found in the Australian Workplace. Check with your employer or health and safety officer. Stay informed and become aware of the dangers that surround you. This chemical is included on the list of recognised hazardous chemicals from the Safe Work Australia - Hazardous Substances Information System (HSIS) that is based on the Globally Harmonised System of Classification and Labelling of Chemicals (GHS)

    Work Health and Safety (WHS) Regulations are the basis for hazardous chemicals regulations in Commonwealth, State and Territory jurisdictions in Australia. Under the model WHS Regulations, manufacturers and importers of substances, mixtures and articles supplied for use in workplaces are required to determine whether they are hazardous to health and safety before supply. The model WHS Regulations mandate that the hazards of a chemical as determined by the Globally Harmonised System of Classification and Labelling of Chemicals (GHS) must be included in safety data sheets and on labels. There are transitional arrangements in place for moving to the GHS-based system.

    The GHS Hazardous Chemical Information List contains chemicals classified by an authoritative source (such as the European Commission or NICNAS) in accordance with the Globally Harmonized System of Classification and Labelling of Chemicals (the GHS). This list contains the vast majority of chemicals currently in HSIS. This list and its detail are regularly updated by Work Safe Australia. The model Work Health and Safety (WHS) Regulations require chemicals to be classified in accordance with the Globally Harmonised System of Classification and Labelling of Chemicals (GHS). However transitional arrangements allow use of classification information in HSIS derived from the Approved Criteria until the 31 December 2016.
  • toxin chemical structure pubchem
  • FORMULA: C9H7MnO3
  • DATA SOURCES: DATA SOURCES: ARTICLE 4 | T3DB | PubChem | Safe Work Australia - Hazardous Substances Information System (HSIS)
  • LAST UPDATE: 28/04/2018

  Health Associations

Mostly focused on Health Implications of Long Term Exposure to this substance

  • SYMPTOMS: Manganese mainly affects the nervous system and may cause behavioral changes and other nervous system effects, which include movements that may become slow and clumsy. This combination of symptoms when sufficiently severe is referred to as “manganism”. (L228)
  • POSSIBLE HEALTH CONSEQUENCES: Manganese mainly affects the nervous system and may cause behavioral changes and other nervous system effects, which include movements that may become slow and clumsy. This combination of symptoms when sufficiently severe is referred to as “manganism”. (L228) | Manganese is absorbed mainly via ingestion, but can also be inhaled. It binds to alpha-2-macroglobulin, albumin, or transferrin in the plasma and is distributed to the brain and all other mammalian tissues, though it tends to accumulate more in the liver, pancreas, and kidney. MMT is metabolized by cytochrome P-450 enzymes into hydroxylmethylcyclopentadienyl manganese tricarbonyl and carboxycyclopentadienyl manganese tricarbonyl. These metabolites are excreted in the urine and faeces. (L228)
  • ACTION OF TOXIN: Manganese is a cellular toxicant that can impair transport systems, enzyme activities, and receptor functions. It primarily targets the central nervous system, particularily the globus pallidus of the basal ganglia. It is believed that the manganese ion, Mn(II), enhances the autoxidation or turnover of various intracellular catecholamines, leading to increased production of free radicals, reactive oxygen species, and other cytotoxic metabolites, along with a depletion of cellular antioxidant defense mechanisms, leading to oxidative damage and selective destruction of dopaminergic neurons. In addition to dopamine, manganese is thought to perturbations other neurotransmitters, such as GABA and glutamate. In order to produce oxidative damage, manganese must first overwhelm the antioxidant enzyme manganese superoxide dismutase. The neurotoxicity of Mn(II) has also been linked to its ability to substitute for Ca(II) under physiological conditions. It can enter mitochondria via the calcium uniporter and inhibit mitochondrial oxidative phosphorylation. It may also inhibit the efflux of Ca(II), which can result in a loss of mitochondrial membrane integrity. Mn(II) has been shown to inhibit mitochondrial aconitase activity to a significant level, altering amino acid metabolism and cellular iron homeostasis. (L228) | Manganese interferes with amino acid metabolism by inhibiting aconitase, resulting in an increase in citrate levels. It is also believed that this direct disruption of the catalytic [4Fe-4S] cluster of aconitase by manganese produces iron regulary protein 1, resulting in alterations in cellular iron homeostasis. (A159)
  • TOXIN SITES OF ACTION IN CELL: "Cytoplasm", "Extracellular"
  • Additional Exposure Routes: Methylcyclopentadienyl manganese tricarbonyl (MMT) is a chemical compound of manganese. It was initially used as a supplement to the gasoline additive tetraethyl lead to increase a fuel's octane rating, then later also used in unleaded gasoline. It has been banned in various countries in the past due to its toxicity, but is available in most places today, despite controvery over its safety. (L239)

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