Many claim that the mercury is hazardous causing a variety of illnesses including brain damage, birth defects, multiple sclerosis, memory loss, chronic fatigue and allergies. On the other hand the American Dental Association maintains their stand that mercury amalgam fillings are safe and warns that "it is against the ADA code of ethics for a dentist to suggest or recommend the removal of amalgam restorations for the alleged purpose of removing toxic substance from the body."

The fillings referred to as "silver" are actually a mixture of silver, tin, copper, and mercury, and are more properly called amalgam fillings. The silver, tin, and copper are provided in a powder form by various manufacturers, with silver being the major constituent (40 to 70 percent), and tin and copper constituting 4 to 33 percent each, depending on the manufacturer. This powder is then mixed rapidly with mercury in a special machine, usually by the dental assistant, yielding a liquid that is from 50 to 60 percent mercury. The filling material is then placed in the tooth and smoothed with various dental tools. Mercury vapor is released very slowly into the mouth from the fillings while chewing, getting the teeth polished, if the filling breaks, is being placed or taken out. The dental office and staff are the ones at most exposed to the dangerous phase of mercury, by handling it improperly, before it is mixed and hardened.

Mercury amalgam fillings were first introduced over 150 years ago by a chemist, as an inexpensive and durable filling material. Even at that time there was controversy among the dentists, over its use. Most studies against the use of mercury amalgam fillings indicate that the long term affects occur very slowly with a cumulative affect as mercury vapor is released while chewing. If a true allergy exists (less than 1 percent of the population) a reaction can be noticed within days of having the filling placed – such as bumps or lesions in or around the mouth, or a rash. The U.S. Public Health Service reported in a 1993 study that they did not find any evidence for health hazards, but also concluded that there wasn't enough evidence to conclude its safety either.

There are some holistic dentists who recommend everyone take their mercury fillings out and replace them with a white plastic, porcelain filling or gold. However, as mentioned earlier, taking these mercury fillings out, will release more vapor than leaving them in. Some web sites even sell supplements to counteract the toxic affects of the mercury.

My recommendation is that as the mercury fillings become old or for other reasons need to be replaced, use another filling material. However, if you have a mysterious illness that cannot be explained, such as a neurological problem, you may want to replace the mercury. If this was the case, it's important to go to a dentist that is "mercury-free" and doesn’t use this type of filling in their office. At least you'll be assured that the environment does not carry further risks.

The air and water are other ways by which mercury contaminates us and our environment. A rise in mercury level has been found in such places as Lake Tahoe in California, Florida’s Everglades and lakes found in New Zealand and Nova Scotia. Scientists contributed the cause of the rise in mercury in these areas to airborne industrial emissions, since there were no mines, industrial polluters or sewage plants nearby. A major source of contaminations in the air arise from crematories burning human bodies with fillings in their teeth. The mercury eventually falls back to the soil or water and contributes to fish contamination.

Although there may be no direct link between mercury dental fillings to illness or nervous system damage, the possible contamination to the environment and back to the food chain presents a real threat to our health. According to various studies, once mercury enters the water, it may be converted by micro-organisms into its most dangerous form, methylmercury, a neurotoxin that causes brain damage. Mercury from improperly disposed of dental fillings (from dental offices, silver filling refineries or crematories), old mines or disposal of many household products containing mercury, is taken up by algae and bacteria which then are incorporated into insects and other plankton, eaten by fish, birds and mammals and eventually reach human beings.

To do your part in decreasing mercury contamination to our environment, whether our bodies or planet, choose a dentist that is "mercury-free". A very interesting study indicates the primary means by which we come into contact with mercury in its most dangerous form, methylmercury, is by eating contaminated fish. How often you eat fish, the type and which body of water the fish came from influences the amount of contamination. For example a person buying fish from a health food store once or twice a week does not have to worry about health risks, however a pregnant woman eating fish daily caught from San Francisco Bay could well be causing brain damage to her unborn infant.