Chemical exposure
Exposure to chemical toxin reduces the taste sensation. Chemicals present in pesticides, cosmetics, detergents and industrial environments can enter the body through the skin, mouth or nasal passages. Inhaling high levels of lead and mercury are the major chemicals that cause metallic taste.
Lead is very harmful to children and adult and can be seen in paints, water and air. People that renovate homes, work with batteries have a higher risk of lead poisoning which leads to alteration in taste. The best way to avoid lead poisoning is to not use lead painting in homes or offices.
Mercury are found in homes and work sites. They are present in broken thermometers or blood pressure machines. Removing these sources is the best way to avoid mercury poisoning. It is important to visit a medical doctor if any sign of mercury poisoning is noticed.