claiming that dental amalgam “is considered a safe, affordable, and durable material,”91 studies specific to dentists and mercury exposure via amalgam have produced worrisome results. In a neurobehavioral study of dentists exposed to elemental mercury at work, researchers found that the dentists did significantly worse on mental acuity and motor skill tests than control subjects; in addition, as years of exposure to elemental mercury in amalgam increased, a dentist’s test performance significantly decreased.92 Female dentists and dental assistants exposed to mercury in another study were also found to have significantly more reproductive failures, including more painful and irregular menstrual disorders as well as more miscarriages and increased congenital malformations in infants.93
Dental amalgam has also been shown to leach mercury into the mouth, which can emerge in the form of vapors or be swallowed if pieces of amalgam break off. Studies vary widely on the quantities of mercury people are exposed to in this fashion. Researchers with the Department of Materials Science at University of Virginia’s School of Engineering and Applied Science found that both stannous and sodium fluorides, active ingredients in commercial toothpastes and mouthwashes, played a role in increased corrosion rates of mercury fillings.94 Multiple adverse health effects have been correlated to the presence of dental amalgams, including one study that found that mothers who had six or more dental amalgams during pregnancy and later had a child diagnosed with autism were more than three times more likely for that diagnosis to be severe autism than the autistic children of mothers with five or fewer mercury fillings.95
Studies have also revealed that microwave radiation from cell phones and magnetic resonance imaging (MRI) significantly accelerated the leaching of mercury from dental amalgams, giving cause for concern about people who have these fillings coming into everyday contact with electromagnetic fields (EMF), including the ubiquitous Internet Wi-Fi hotspots found in most urban and suburban areas.96
Interestingly, even the cremation of human bodies releases enormous quantities of mercury vapor into the atmosphere due to the burning of mercury amalgam dental fillings found in most people. A 1994 study conducted by Japanese researchers found that a single crematorium released approximately 9.4 kg of mercury into the atmosphere each year.97
DENTISTRY—HOW DENTISTRY POLLUTES OUR BODIES WITH MERCURY
One source of potential toxin exposure that may not immediately come to mind is dental amalgam (i.e. “fillings”).
Over 90 percent of American adults have received one or more dental fillings as a remedy for their cavities. The vast majority of these fillings are “silver” amalgams composed of 50 percent elemental mercury (Hg) and other metals that are less toxic than mercury.
According to the CDC and the National Institute of Dental and Craniofacial Research, Americans between the ages of twenty and sixty-four have an average of 3.28 cavities each.1,2 Though some 23 percent of these cases go untreated, a staggering number of cavities (in the hundreds of millions) have been treated with fillings containing mercury, a well-known heavy metal toxin and brain-damaging element.
Research has shown that these amalgams pose an ongoing risk, as they continuously release mercury vapor, which is in turn inhaled into the body, where it wreaks havoc on cell integrity. About 80 percent of the elemental mercury vapor is inhaled through the lungs and enters into the bloodstream.3 From there, significant amounts of mercury can cross the blood–brain barrier where it is transported to the brain via blood. Additionally, small pieces of mercury can also be swallowed if the amalgam breaks or chips.
Studies on the impact of mercury-containing fillings have concluded that amalgams contribute the vast majority of mercury that accumulates in the human body,4 with the World Health Organization naming amalgams as the most significant source of inorganic mercury in the general population, contributing to half of overall exposure. The WHO further reported that frequent activities among the entire population such as chewing, including both eating and chewing gum, and brushing teeth can increase mercury vapor emissions by more than fivefold.5 Worse, the active ingredients in commercial toothpastes and mouthwashes—stannous and sodium fluorides—have been found in studies to increase amalgam corrosion rates.6 Higher rates of mercury uptake among the general population have additionally been documented for frequent gum chewers and those who grind their teeth.7
Research has also shown that when people with dental amalgams are exposed to microwave radiation from cell phones and magnetic resonance imaging, mercury release from dental amalgam accelerates.8 Considering how many urban and suburban areas are bathed in perpetual electromagnetic fields due to a myriad of Wi-Fi hotspots these days, this finding is particularly worrisome and demands further study.
According to the EPA, the adverse health effects of breathing elemental mercury vapor include mood swings, irritability, nervousness, tremors, insomnia, muscle atrophy and twitching, headache, nerve response and sensation changes, cognitive dysfunction, and—at very high levels—kidney and respiratory failure, and even death.9
Autopsies used in an Italian research study concluded that subjects with twelve or more fillings had significantly higher levels of mercury in the brain and other tissues than did subjects who had three or fewer fillings.10 Rat studies confirmed that exposure to amalgam vapors increased concentrated brain mercury by as much as eight times, while accumulation in kidney tissue after exposure was also high.11
Several studies have linked the presence of mercury fillings with mental disorders. One found that multiple sclerosis patients with fillings had far higher levels of depression and sudden feelings of anger and irritability than those who had their amalgam fillings removed.12 A related study found that mental issues were improved or eliminated within about ten months of removing mercury amalgams. A study on women found those with amalgams showed tendencies toward uncontrolled anger, a lack of happiness and satisfaction, and an inability to make decisions as compared with those without amalgams.13 Even low doses of exposure to dental amalgam mercury have been shown to contribute to adverse behavioral effects in relation to toxicity burden in the body.14
After years of complaints of symptoms and worry over the risk of toxicity by the public and researchers, the FDA reclassified mercury from a Class I (least risk) to Class II (more risk) in 2009. Further, the agency officially classified dental amalgams (composed of elemental mercury, silver, tin, copper, and a powdered alloy) as a Class II restorative medical device.15
Exposure to mercury is also a serious concern for dentists and dental assistants. Studies have long found suicide rates among workers in the dental industry to be significantly higher than in other occupations.16 Although the full explanation for this is not clear, chronic exposure to mercury vapors and elemental mercury may play a significant role.17 Already the available data show that there is reason to associate amalgams with mental health issues and depression. Considerable research has gone into investigating occupational exposure for dental professionals, who consistently have higher rates of mercury in their bodies alongside notable adverse health effects.
A 2001 study published in the British Dental Journal found elevated blood mercury levels not only in the dental students working with restorative amalgams, but also in surrounding students and staff who worked in the same environment but had no direct contact with the materials.18
Researchers have further concluded that, when compared to control subjects, dentists perform significantly worse on mental acuity and motor skills tests; worse, the longer a dentist had been exposed to elemental mercury, the poorer his or her performance was on the tests.19 Researchers have also found memory disturbances and kidney disorders among dentists.20
Studies have also shown that female dentists and dental assistants are
