Toxic metals in the body

(1)  In trace amounts, certain metals have benefical physiological functions in the body. 

Physiological metals:

• Zinc - constituent of >300 enzymes involved in gene expression, cell growth and repair
• Selenium - component of glutathione peroxidase enzyme needed for production of glutathion -the "king"of the body's antioxidants
• Iron - constituent of haemoglobin, myoglobin and several enzymes.
• Copper- constituent of hair and elastic tissue in skin, bone and organs
• Manganese
• Chromium (III) - maintains normal glucose metabolism / cofactor for INSULIN
• Molybdenum
• Vandium
• Lithium
• Others

Some metals are not physiological but can be used therapeutically in trace amounts:

• Silver (antibiotic)

(2) Some metals have no business being in the body at all and generally have a toxic effect on health

(even physiological metals can be toxic when their presence exceeds their physiological norm):

Heavy metals enter the body from various sources (consumed, breathed, transdermally acquired or via other contact):

• Dental amalgam (silver colored ones contain mercury)
• Toxic metals pass through the placenta from mother to child
• Vaccinations
• Food - Eating any amount of tuna fish, salmon or other larger fish, also shellfish, seafood, or seaweed (except kelp) causes mercury toxicity (shellfish also contain cadmium). Aluminum found in antacids, canned foods, aluminum foil, some baking sodas.   Arsenic is in CAFO-produced meat
• Water - E.g. arsenic , aluminum, copper, and more
• Cookware - E.g iron or aluminum pans contaminate food
• Air pollution - E.g. arsenic, cadmium; coal burning adds mercury to the air, etc.
• Cigarette and marijuana smoke - Cadmium (high levels in smokers); using a water pipe reduces contamination
• Household chemicals - E.g. arsenic in wood preservatives, cadmium in some paints
• Lead water pipes - introduce lead into water
• Gasoline - lead
• Batteries - lead

Miners, electricians, plumbers, auto mechanics and other mechanics in such as diesel engine repair, tool repair etc are at high risk for metal toxicity

References

Chemistry Explained - Heavy Metal Toxins