Aluminum
Sources
Antacids, antiperspirants, baking powders, beverage/food cans, buffered aspirin, canned foods, city water supplies, cookware and utensils, cosmetics, foil, lipstick, ore smelting plants, processed cheeses, etc.
General Physiological Effects
Abundant in today’s environment and toxic in excessive quantities, aluminum is mostly absorbed through the skin, lungs and intestinal tract. Aluminum toxicity seems to affect the bones (causing brittleness or osteoporosis), kidneys, stomach, and brain. Research suggests that it may also contribute to Alzheimer’s disease, Parkinson’s, dementia, and other neurological disorders.
Arsenic
Sources
Chemical processing plants, cigarette smoke, drinking water, fungicides, meats and seafood, metal foundries, ore smelting plants, pesticides, polluted airm specialty glass products, weed killers, wood preservatives, etc. 
General Physiological Effects
Extremely poisonous as well as colorless and odorless, arsenic can enter the body through the mouth, lungs and skin. Arsenic toxicity seems to predominantly affect the skin, lungs and gastrointestinal system, and may cause nervous disorders, deteriorated motor coordination, respiratory diseases, and kidney damage as well as cancers of the skin, liver, bladder and lungs.
Cadmium
Sources
Air pollution, batteries, ceramic glazes/enamels, cigarette smoke (first and second hand), tap and well water, food (if grown in cadmium contaminated soil), fungicides, mines, paints, power and smelting plants, seafood, etc.
General Physiological Effects
Exposure to cadmium can occur through inhalation or ingestion in places or situations where cadmium products are used, manufactured, or ingested. Cigarette smoke is the biggest source of cadmium toxicity, which seems to primarily affect the lungs, kidneys, bones, heart disease, and also causes yellow teeth and anemia. Cadmium also seems to contribute to autoimmune thyroid disease.
Lead
Sources
Air pollution, ammunition, auto exhaust, batteries, containers for corrosives, contaminated soil, cosmetics, fertilizers, foods (if grown in lead-contaminated soil), hair dyes, insecticides, lead-based paints, lead-glazed pottery, pesticides, solder, tobacco smoke, water (if transported via lead pipes), etc.
General Physiological Effects
Lead is a naturally occurring neurotoxin. Although many lead containing products (such as gasoline and house paints) were banned in the 1970’s, contamination still occurs today mostly by drinking lead contaminated water, breathing lead-polluted air, and living in or near older painted buildings and certain toxic industrial areas. Lead toxicity primarily targets the nervous system kidneys, bones, heart and blood, and poses greatest risk to infants, young children and pregnant women. It can affect fetal development, delay growth, and may also cause attention deficit disorder, learning disabilities, behavioral defects, and other developmental problems.
Mercury
Sources
Air pollution, barometers, batteries, cosmetics, dental amalgam fillings, freshwater fish (bass and trout), fungicides, insecticides, laxatives, paints, pesticides, saltwater fish (tuna and swordfish), shellfish, tap and well water, thermometers, thermostats, vaccines, etc.
General Physiological Effects
Both poisonous and dangerous, mercury is found throughout our environments in many forms and also in many household items. Mercury often permeates the ground we walk on, and is also found in some childhood vaccines today because of its use and preservative. Mercury as used in dental fillings is the primary source of toxic exposure, and in vapor form accounts for the majority of all exposures (via inhalation). Mercury toxicity can affect the central nervous system, kidneys and liver. Research suggests that this heavy metal may also contribute to autism and multiple sclerosis.