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“Dental amalgam has been controversial ever since it was introduced, early in the nineteenth century, because of its mercury content. People of the Napoleonic era knew full well that mercury was poisonous, and the best that anyone has ever claimed about amalgam is that the mercury exposure may be too small to hurt anyone. Over time, though, a great body of evidence has accumulated showing that mercury is released from amalgam in significant quantities, that it spreads around the body, including from mother to fetus, and that the exposure causes physiological harm. A growing number of dentists, physicians, researchers, citizen activists, politicians, and regulators have come to the conclusion that the time has come to consign dental amalgam to the ‘dustbin of history.’ This article will sketch out the main points of the scientific case against amalgam.”

“25 studies comprising 5821 patients…The Swedish Association of Dental Mercury Patients (Tf) started the more systematic
investigation of symptoms related to amalgam and the effects replacing the alloy with less toxic materials (Tf-bladet, 1986). Since then a considerable number of studies of varying quality have been presented, most of them by dentists. Most of them give a very consistent result: there is hardly any medical treatment which gives so positive results on so many health problems as amalgam removal.”

“Mercury is a very useful metallic element that, while not particularly abundant in nature, can play an important role in the overall health of humans and animals. This article discusses the benefits and toxicological consequences of society’s use of mercury. It also will focus upon the mining, processing, and uses of mercury in the United States, and then highlight the amounts of mercury that are released as wastes. Along the way, three important questions are addressed: How much mercury is released by human activities and by natural events? Do these releases pose a risk either to humans or to the environment in general? How does this information apply to dentistry?”

AIMS:

To establish and analyse reference data for the mercury burden of patients with and without amalgam fillings.

METHODS:

Atomic absorption spectroscopy was used to quantify Hg concentrations in the scalp hair and urine (before and after application of dimercaptopropane sulphonate), and Hg release from dental amalgams (using a newly developed, amalgam specific chew test), in 2223 subjects.

RESULTS:

50th centiles were 1.3 microg Hg/g creatinine in basal urine, 32 microg Hg/g creatinine after DMPS application, 454 ng Hg/g in hair, and 27 microg Hg per g of chewing gum, which corresponds to about 1 micro g Hg released per minute of chewing. Total Hg intake (from ambient air, drinking water, food, and amalgams) of most patients is well below the provisioned tolerable weekly intake (PTWI) defined by the WHO, unless extremely Hg rich food is consumed on a regular basis. However, for patients exceeding the 75th centile in chew tests, total Hg intake exceeds the PTWI by about 50%, even at the low limit of intake from food. In the absence of occupational exposure, significant Hg release from dental amalgams is a necessary but insufficient condition to obtain a high long term body burden. After removal of dental amalgams, chew tests no longer exhibit oral Hg exposure, while basal urine Hg content and DMPS induced excretion display a exponential decrease (half life about 2 months in both cases).

CONCLUSIONS:

A standardised procedure for evaluation of the magnitude and origin of the Hg burden of individuals has been developed, which, by comparison with the database presented here for the first time, can serve as a diagnostic tool.”

“The extensive use of fish meal as a source of protein for poultry and swine may lead to additional exposure to methylmercury (MeHg). We determined the concentration of MeHg and inorganic mercury (I-Hg) in blood and total mercury (T-Hg) in hair in 27 persons (9 men and 18 women, 20-58 years of age) who stated that they had consumed no fish for a period of 2 years or more. The participants answered a food frequency questionnaire and reported their number of dental amalgam fillings. The MeHg concentrations in blood (median, 0.10 microg/L; range, 0.0-1.0 microg/L) were very low and did not constitute a concern for health effects. We also analyzed selenium (Se) in serum. The median concentration was 76 microg/L (range, 53-103 microg/L), which is in agreement with previous studies of the Swedish general population, indicating that the Se status of non-fish-eating individuals is not substantially lower than that of people who include fish in their diet. We found a significant association (P=0.002) between the number of dental amalgam fillings and the I-Hg concentration in blood (median, 0.09 microg/L; range, 0.03-0.57 microg/L). The T-Hg in hair (median, 0.06 mg/kg; range, 0.04-0.32 mg/kg) was significantly associated (R2=0.89; P<0.001) with the MeHg in blood, but not with the I-Hg in blood. Therefore, the T-Hg in hair seems to reflect MeHg exposure and not I-Hg exposure even in persons with no intake of fish.”

“Alongside food, emissions from amalgam fillings are an essential contribution to man’s mercury burden. Previous methods for the determination of intraoral mercury vapor (Hg degrees ) release used principally some form of preconcentration of Hg on gold (film or wool), allowing relatively few measurements with unknown precision and sensitivity at selected times. Recently available computer-controlled Hg detectors operating on Zeeman atomic absorption spectroscopy (ZAAS) facilitate the direct real-time measurement of Hg degrees concentrations. It was the aim to adapt this method for a comparative investigation of emission processes from fillings in situ and from amalgam specimens in vitro. In addition to the ZAAS instrument, the apparatus consisted of a pump, magnetic valves, an electronic flow controller and a handle with a disposable mouth piece for aspiration of oral air. A programmable timer integrated the computer-controlled instrument operation and the data collection into a standard sampling protocol. A fast exponential decay of the emission was found after stimulation of amalgam specimens and of fillings in situ (halftimes 8.6 and 10.7 min). Precision was evaluated by a series of measurements on a single patient which indicated a consistently low coefficient of variation between 18% and 25%. After insertion of a few new fillings, sensitivity was high enough to detect a significant increase in emission against the background emission from the majority of old fillings. Zeeman-AAS in connection with a semi-automated sampling protocol and data storage provides precise in-situ measurements of Hg degrees emission from dental amalgam with real-time resolution. This facilitates the detailed exploration of the Hg degrees release kinetics and the applicability to large-scale studies.”

“Mercury (Hg) release from dental offices has become an acute issue for the dental profession and has resulted in efforts by regulators to mandate both the use of Best Management Practices (BMPs) as well as the installation of amalgam separators. Concern has been expressed by some regarding the efficacy of amalgam separators in reducing the Hg loads to wastewater treatment plants (WWTPs). Data from several Publicly Owned Treatment Works (POTWs) serving areas with installed bases of separators suggest these devices can substantially reduce Hg burdens to WWTPs. The data consists of Hg levels in sewer sludge (biosolids) and in some cases includes Hg concentrations in WWTP influent and effluent. Data comes from various geographical locations, and suggest separators can have a positive effect in reducing the amount of Hg reaching WWTPs.”

“AIM:

A study of 180 dentists in the West of Scotland was conducted to determine their exposure to mercury during the course of their work and the effects on their health and cognitive function.
DESIGN:

Data were obtained from questionnaires distributed to dentists and by visiting their surgeries to take measurements of environmental mercury.

METHODS:

Dentists were asked to complete a questionnaire including items on handling of amalgam, symptoms experienced, diet and possible influences on psychomotor function such as levels of stress and alcohol intake. They also completed the 12-item General Health Questionnaire. Dentists were asked to complete a dental chart of their own mouths and to give samples of urine, hair and nails for mercury analysis. The dentists were visited at their surgeries where environmental measurements were made in eight areas of the surgery and they undertook a computerised package of psychomotor tests. One hundred and eighty control subjects underwent a similar procedure, completing a questionnaire, having their amalgam surfaces counted, giving urine, hair and nail samples and undergoing the psychomotor test procedure.

RESULTS:

Dentists were found to have, on average, urinary mercury levels over 4 times that of control subjects although all but one dentist had urinary mercury below the Health and Safety Executive health guidance value of 20 mumol mmol(-1) creatinine. Urine was found to be a better biological marker for mercury exposure than hair or nails.Dentists were significantly more likely than control subjects to have suffered from disorders of the kidney but these symptoms were not significantly associated with their level of mercury exposure as measured in urine. One hundred and twenty two (67.8%) of the 180 surgeries visited had environmental mercury measurements in one or more areas above the Occupational Exposure Standard (OES) set by the Health and Safety Executive. In the majority of these surgeries the high levels of mercury were found at the skirting and around the base of the dental chair. In 45 surgeries (25%) the personal dosimetry measurement (ie in the breathing zone of dental staff) was above the OES.

CONCLUSION:

On the basis of these findings, it is recommended that greater emphasis should be made relating to safe handling of amalgam in the training and continuing professional development of dentists, that further studies are carried out on levels of mercury exposure of dental team members during the course of their working day, and that periodic health surveillance, including urinary mercury monitoring, of dental personnel should be conducted to identify possible effects of practising dentistry.”