Reactions between chemical compounds on the skin and metals such as iron and copper can generate a metallic smell, explains Nature. A copper imbalance in the body, which triggers excessive yeast growth, can also cause a metallic odor, notes Dr. Lawrence Wilson. Gum disease, also known as periodontal disease, can similarly precipitate a metallic mouth odor, according eMedicineHealth. Certain medications and dental appliances may trigger a metallic body odor, reports CNN Health.
Reactions between the skin and iron or solutions containing iron ions with a twofold positive charge generate the cocktail of gaseous compounds that humans identify as a metallic smell, opines Science Daily. The process commences with reactions between skin perspiration and iron, which immediately corrodes the metal and generates doubly negative iron ions.
These ions then quickly decompose certain compounds, lipid peroxides, that are present in the skin oils produced by the body, generating the chemical 1-octen-2-one, which exudes a strong fungal-metallic smell even in very small quantities, and other gaseous compounds, reports Science Daily. At the end of the process, the ions become triple charged and stop generating compounds that humans can smell. Because blood contains iron atoms, rubbing it on the skin triggers the same process, which is why blood seems to give off a metallic smell.
Apart from iron, contact with copper precipitates a similar process, notes Nature. Researchers believe that each person generates a unique smell after interaction with these metals and that the resulting odor may vary if an individual is unwell. It may be therefore possible to exploit these smells for diagnostic purposes.