Taking a bite out of the harmful effects of mercury in dental fillings: advocating for national legislation for mercury amalgams.

• Author: Baga, Kimberly M.

"Having an amalgam filling placed in a tooth is like having a time bomb in your mouth waiting to go off." (1)

1. INTRODUCTION II. HISTORICAL OVERVIEW III. FORMS OF MERCURY IV. POISON PALETTE? FACTS ABOUT AMALGAMS V. THE MERCURY AMALGAM CONTROVERSY VI. LITIGATION IS AN INSUFFICIENT REMEDY VII. REMOVAL IS AN INSUFFICIENT REMEDY VIII. ENVIRONMENTAL IMPACT IX. LEGISLATION IN OTHER COUNTRIES X. STATE-LEVEL LEGISLATION XI. NATIONAL LEGISLATION XII. CONCLUSION I. INTRODUCTION

   Mary Stephenson, a fifty-nine-year-old grandmother, visited dozens of counselors and experimented with an array of antidepressants but nothing worked to curb her suicidal feelings. (2) Janie McDowell, a fifty-six-year-old housewife, suffered from hand tremors, leg-muscle spasms, recurring nausea, chronic bladder and kidney infections, severe depression, short-term memory loss, and slurred speech. (3) Freya Koss, a former event planner, experienced dizziness and double vision. Physicians misdiagnosed Koss with lupus, multiple sclerosis, and, finally, myasthenia gravis. (4) The common theme among these medical tragedies is that the above victims all returned to being healthy, active adults after the removal of their mercury amalgam dental fillings. (5)

   Amalgam is the name dentists give the silver filling material used to reconstruct damaged teeth. (6) Approximately nineteen out of every twenty Americans suffer from dental cavities, and more than 200 million people have at least one cavity in their mouth filled with dental amalgam. (7) The amalgam composite contains a mixture of mercury, powdered silver, tin, and copper. (8) Mercury, a highly toxic substance, has been linked to neurological problems, gastrointestinal problems, Alzheimer's disease, brain damage in children, cardiac dysfunction, impaired kidney functioning, and a host of other ailments. (9) Experts vehemently disagree on whether the mercury found in dental amalgam is in a large enough quantity to be harmful to humans; however, the evidence against using mercury in dental fillings continues to grow. (10) The use of mercury amalgam dental fillings is dangerous, and there needs to be national legislation to prohibit its use.

   This paper begins with a historical look at the use of mercury in dental fillings. Part III discusses the forms of mercury, while Part IV discusses the composition of mercury amalgams. Part V focuses on the mercury amalgam controversy and highlights the major arguments made by pro-amalgam and anti-amalgam activists. Parts VI and VII, respectively, explain why litigation and removal of fillings are insufficient remedies for the mercury amalgam problem. Part VIII addresses the environmental impact of mercury amalgams. Part IX examines legislation enacted in other countries that prohibit, limit, or discourage the use of mercury amalgams. Part X addresses the inadequacies of state-level legislation as a solution. Part XI proposes national legislation as the best solution to the mercury amalgam problem. Additionally, the final part recommends changes to the currently proposed national legislation.

2. HISTORICAL OVERVIEW

   The use of mercury as dental filling material is a practice with a long history throughout the world. (11) The Chinese used a mercury-containing "silver paste" as early as the seventh century to repair decaying teeth. (12) Mercury intrigued the alchemists of China because it is the only metal that is a liquid at room temperature. (13) Furthermore, the ancient Chinese also knew that shavings of other metals such as copper, tin, and silver dissolved in liquid mercury. (14) By the early 1800s, the popularity of "silver paste" for dental fillings had spread to England and France, (15) eventually arriving in North America in the 1830s. (16)

   Joseph Bell, a British chemist, created the modern amalgam filling by combining melted coins and mercury. (17) The problem with this compound was that the impurities in the metal used for coins caused the amalgams to expand, which often caused the teeth to fracture. (18) Over time, improvements were made in the mercury amalgam compound, which led to a durable dental filling material. (19) Although the expansion problem was solved, many dentists continued to express concerns about the use of mercury in amalgams. (20) As early as the 1930s, it was already a well-known and accepted fact that mercury exposure, even in small amounts, could result in mercurial poisoning. (21)

   In 1845, the American Society of Dental Surgeons (ASDS) advocated strongly against the use of mercury amalgams and required its members to sign a pledge to stop using mercury amalgams in their practices. (22) Over the next decade, several members of the ASDS were suspended for malpractice when they placed amalgam fillings in patients in violation of their ASDS pledge. (23) Eventually, membership in the ASDS declined, and it dissolved in 1856. (24) The American Dental Association (ADA), founded in 1859, arose to take the place of the ASDS. (25) However, the ADA's position on mercury amalgams was in direct opposition to that of the former ASDS. The ADA strongly advocated for the use of amalgam as a safe tooth-filling material. (26) The public was receptive to the use of amalgam fillings because their only alternatives at the time were painful extractions without anesthesia or expensive hot gold fillings. (27) The support from the ADA, coupled with the low cost of the mercury amalgam fillings, effectively overshadowed the warnings from mercury amalgam opponents. (28) Concerns about the safety of amalgam fillings briefly resurfaced in Germany in the 1920s (29) but, subsequently, diminished without a clear resolution. (30) The debate over the safety of mercury amalgams continues today, and advances in scientific tests have helped bolster the case against amalgams. (31)

3. FORMS OF MERCURY

   Mercury is found in three forms: metallic or elemental, inorganic, and organic. (32) Metallic or elemental mercury is a liquid at room temperature and is silver-white in color. (33) It is the purest form of mercury and is used in fluorescent light bulbs, batteries, dental fillings, thermometers, and some light switches. (34) At room temperature, exposed metallic mercury can evaporate. (35) This invisible, odorless vapor is harmful to humans. (36)

   Inorganic mercury is mercury combined with other elements. (37) Inorganic mercury usually forms white powder or crystals (with the exception of cinnabar, which is a red powder). (38) The third form of mercury, organic mercury, is formed when mercury combines with carbon. (39) The most common organic mercury compound is methylmercury, which is produced when microscopic organisms convert inorganic mercury into methylmercury. (40) Methylmercury is often found in soil or water, and the primary way humans are exposed to this type of mercury is through consumption of fish that contain methylmercury. (41)

   All three forms of mercury (metallic, inorganic, and organic) are found in the body. (42) Mercury in vapor form is usually attributed to mercury amalgam fillings. (43) When the vapor escapes from the fillings, it enters the bloodstream via absorption through the lungs and intestinal tract. (44) Mercury vapor primarily targets the brain and central nervous system. (45) Chewing, drinking hot foods, and tooth brushing all exacerbate the release of mercury from dental fillings. (46)

   The second type of mercury found in the body is mercury in the ionic form containing two positive charges. Ionic mercury does not move around or through tissue like other forms of mercury, but ionic mercury is, arguably, the most destructive form. It usually damages the kidneys and gastrointestinal tract. (47)

   The final form of mercury found in the body is methylmercury. (48) Methylmercury is the organic form of mercury. (49) It is formed when mercury vapor and ionic mercury come into contact with bacteria in the mouth, stomach and intestinal tract, or in the bloodstream. (50) This process of conversion is known as methylation. (51) Methylmercury is able to cross any cell membrane or barrier in the body. (52) This includes being able to cross the placenta and the blood-brain barrier. (53) Once methylmercury reaches its destination, it is converted back into ionic mercury. (54) Degeneration and atrophy of the sensory cerebral cortex, paresthesia (numbness and tingling), hearing and visual impairment are all attributed to poisoning by methylmercury. (55)

   For thousands of years, mercury has aided advances in medicine, chemistry, dentistry, and money. (56) In 2001, amalgam sales through dental dealers totaled 39 million dollars, (57) but, today, mercury is banned or in the process of elimination in almost every aspect of society because modern scientists acknowledge mercury's dangers. (58) For example, mercury use is being reduced in hospitals (59) and schools nationwide. (60) Additionally, mercury-containing compounds are no longer recognized as safe for veterinary use. (61) Recent legislation also prohibits the use of mercury in childhood immunizations. (62)

   The Environmental Protection Agency (EPA), the Food and Drug Administration (FDA), and the World Health Organization (WHO) all establish "safe limits" for daily mercury exposure. (63) However, there are substantial variations in their recommendations primarily because of the different safety margins used by each organization. (64) The EPA sets the lowest limit at 0.1 mg/kg body weight per day. (65) These limits are not invariable nor do they mean that negative reaction is certain to occur above the recommended level. Their levels only mean that mercury exposure below the recommended level should not lead to health problems. (66) Dentists are regularly exposed to 50-4000 mcg/cubic meter of mercury vapor daily. (67) Studies show that glioblastomas (brain cancer) afflict dentists at twice the rate of the general population and that twenty percent of Canadian dentists are on long-term disability pensions...