Mercury

“This study examined the presence of hypersensitivity to dental and environmental metals in patients with clinical disorders complicated with chronic fatigue syndrome. Three groups of patients were examined through medical history, dental examination, and by using a modified test of blast transformation for metals-MELISA(R). The three groups consisted of the following: 22 patients with autoimmune thyroiditis with or without polyglandular autoimmune activation; 28 fatigued patients free from endocrinopathy; and 22 fatigued professionals without evidence of autoimmunity. As controls, a population sample or 13 healthy subjects without any evidence of metal sensitivity was included. Healthy controls did not complain of marked fatigue and their laboratory tests did not show signs of autoimmunity and endocrinopathy. We have found that fatigue, regardless of the underlying disease, is primarily associated with hypersensitivity to inorganic mercury and nickel. The lymphocyte stimulation by other metals was similar in fatigued and control groups. To evaluate clinical relevance of positive in vitro findings, the replacement of amalgam with metal-free restorations was performed in some of the patients. At a six-month follow-up, patients reported considerably alleviated fatigue and disappearance of many symptoms previously encountered; in parallel, lymphocyte responses to metals decreased as well. We suggest that metal-driven inflammation may affect the hypothalamic-pituitary-adrenal axis (HPA axis) and indirectly trigger psychosomatic multisymptoms characterizing chronic fatigue syndrome, fibromyalgia, and other diseases of unknown etiology.”

It was the aim of this investigation to treat 20 volunteers with maximally 5 amalgam fillings by the same comprehensive protocol in which all removals with (n = 8) and without (n = 12) rubber dam had been performed within a few months. Nine amalgam-related parameters indicated a close matching of both groups before removal. In the group without rubber dam, mercury (Hg) levels in plasma increased significantly above preremoval values at days 1 and 3 after removal; they decreased significantly below preremoval values at day 30 in the rubber-dam group and at day 100 in both groups. Excretion rates did not increase significantly in either group, but decreased significantly at day 100 in the protected group. Peak plasma-Hg was 0.6 ng/mL on average at day one and decreased with halftimes of 3 and 43 d in subjects protected by rubber dam. The results indicated that concentrations of total mercury in plasma responded rapidly to changes in the amalgam status and reflected the actual absorption most reliably. Notably, plasma-Hg levels were sensitive enough to detect a transient attenuation of the additional exposure by using rubber dam during the removal of only a few fillings. However, being small in magnitude and lasting 100 d at best, the rubber-dam effect had minor toxicological relevance.

QUESTION:
One of my pregnant patients, a dental hygienist, uses mercury in her workplace, but appears to have no symptoms of mercury toxicity. She has heard that mercury might affect her fetus. What should I recommend to her? What is a safe level of mercury in the air for pregnant women?

ANSWER:
Testing for levels of mercury in whole blood and, preferably, urine is useful for confirming exposure. Currently, mercury vapour concentrations greater than 0.01 mg/m3 are considered unsafe. Also, women of childbearing age should avoid contact with mercury salts in the workplace.

“Many patients attribute their health problems to amalgam and other dental metals. In genetically susceptible indviduals, mercury and gold may function as haptens and elicit allergic and autoimmune reactions. The frequency of metal-induced lymphocyte responses was examined in 3,162 patients in three European laboratories using MELISA(R), an optimized lymphocyte proliferation test. The patients suffered from local and systemic symptoms attributed to dental restorations. The effect of dental metal removal was studied in 111 patients with metal hypersensitivity and symptoms resembling Chronic Fatigue Syndrome (CFS). After consultation with a dentist the patients decided to replace their metal restorations with non-metallic materials. The changes in health and in vitro lymphocyte reactivity were studied by inquiries and follow-up MELISA(R). Lymphocyte reactivity was also analyzed in 116 healthy subjects with no complaints of metal allergy. A significant number of patients had metal-specific lymphocytes in the blood. Nickel was the most common sensitizer, followed by inorganic mercury, gold, phenylmercury, cadmium and palladium. As compared to lymphocyte responses in healthy subjects, the CFS group had significantly increased responses to several metals, especially to inorganic mercury, phenylmercury and gold. Following dental metal removal, 83 patients (76%) reported long-term health improvement. Twenty-four patients (22%) reported unchanged health and two (2%) reported worsening of symptoms. Following dental metal replacement, the lymphocyte reactivity to metals decreased as well. We propose that an inflammatory process induced by metals may modulate the hypothalamic-pituitary-adrenal axis (HPA axis) and trigger multiple non-specific symptoms characterizing CFS and other chronic conditions like myalgic encephalitis (ME) and multiple chemical sensitivity (MCS).”

“Current available literature indicates a risk for metal-induced autoimmunity in man. Metal pathology may be due to toxic or allergic mechanisms where both may play a role. The main factors decisive for disease induced by metals are exposure and genetics which determine the individual detoxifying capacity and sensitivity to metals. This paper reviews the possible mechanisms which may play a role in metal-induced autoimmunity with the emphasis on multiple sclerosis (MS), rheumatoid arthritis (RA) and amyotrophic lateral sclerosis (ALS). We also discuss the role of inflammation-induced changes in the hypothalamus-pituitary-adrenal (HPA) axis as a possible explanation of fatigue, depression and other psychosomatic symptoms observed in these diseases. The increased knowledge about individual sensitivity based on genotype and phenotype variability together with the use of biomarkers for the diagnosis of this individual susceptibility seems to be the key in elucidation of the operating mechanisms. Since metal-induced sensitization may be induced by chronic low-dose exposure, the conventional toxicological approach comparing concentrations of metals in brain autopsies, organ biopsies and body fluids in patients and controls may not provide answers regarding the metal-pathology connection. To address this issue, longitudinal studies of metal-sensitive patients are preferable to the traditional case-control studies.”

Scores on the Minnesota Multiphasic Personality Inventory-2 (MMPI-2), the Million Clinical Multiaxial Inventory-II (MCM-II), and Symptom Check List – 90 (SCL-90) were compared before dental amalgam removal of eight schizophrenia patients to scores six months after amalgam removal. Significant improvement was found in forty-one of the sixty-one component scales of the MMPI-2 and twelve of the twenty subscales including schizophrenia, hysteria, paranoia, and anger. Sixteen of the twenty-five diagnostic scales improved significantly in the MCMI-II including schizoid, anxiety disorders, thought disorders, and bipolar symptoms. Four of nine dimensions improved significantly in the SCL-90 including depression, psychoticism, and obsessive-compulsiive. Because dental amalgam mercury can enter the brain and affect neurotransmitters, the authors hypothesize that removal of the mercury-laden fillings may have contributed to the improved mental health.

“The diagnostic arena now occupied by autoimmune disorders provides us with terms that could be best described as ‘alphabet soup.’  Such problems include: RA (rheumatoid arthritis), HT (Hashimoto’s thyroiditis), HAD (human adjuvant disease), MS (multiple sclerosis), ALS (amyotrophic lateral sclerosis or, more commonly, Lou Gehrig’s disease) and MCTD (mixed connective tissue disease). Should we now add MT (mercury toxicity)?  These conditions plus others, such as Crohn’s disease, Raynaud’s disease, systemic candidiasis, diabetes, and even Alzheimer’s disease are now believed by many to be autoimmune disorders.”

“OBJECTIVES:

This paper aims to give the dental practitioner insight into the potential reproductive effects of handling dental silver amalgam, c.q. mercury.

DATA SOURCES:

Experimental studies on animals, case reports and epidemiologic studies.

STUDY SELECTION:

Experimental animal studies show high doses/concentrations of mercury to increase the risk of reproductive disorders, e.g. infertility, spontaneous abortion, stillbirth and congenital malformations. Some case reports suggest an association between the disorders in humans and high levels of mercury. Therefore, the present article reviews epidemiological studies on the relationship between occupational exposure to mercury, mainly as vapour in the dental practice, and females’ procreative ability. Studies concerning the reproductive effects of males’ occupational mercury body burden are scarce. The reproductive risk of patients’ mercury uptake from silver amalgam fillings is assessed.

CONCLUSIONS:

It seems warranted to conclude that negative reproductive effects from exposure to mercury in the dental office are unproven, but safe levels have not been established. Seemingly problems are unlikely to occur, unless a poor hygiene causes the mercury concentration in the air to exceed females’ time-weighted long-term Threshold Limit Value (TLV). Consequently, in view of the in general low amounts of mercury stemming from dental amalgam fillings, the population at large is at even less risk than dental staff. The effects of occupational elemental mercury concentrations lower than the TLV on the menstrual cycle, conception, male fertility and children’s behaviour need, however, more research.”

“Occupational diseases of dentists and dental nurses were compiled from the Finnish Register of Occupational Diseases. The cases were recorded during 3 3-year observation periods, namely 1982-1984, 1986-1988, and 1992-1994 (i.e., 9 observation years). The relative risk of developing occupational allergic contact dermatitis in different occupations was calculated from the statistics of the years 1986-1991, and was expressed as the age-standardized rate ratio (SRR). During the 9 observation years, the majority of registered occupational diseases of dentists and dental nurses were skin diseases (221/312; 70.8%), followed by occupational repetitive strain injuries (61/312; 19.6%) and occupational respiratory diseases (20/312; 6.4%). The incidence rate (IR) for allergic contact dermatoses/10,000 workers (contact urticaria included) increased from 26 (95% confidence interval (CI) 16-40) in 1982-1984 to 79 (95%, CI 64-97) in 1992-1994. The IR/10,000 of allergic contact dermatoses increased especially for dentists, from 5.4 (95% CI 0.7-19) in 1982 to 67 (95% CI 45-95) in 1992-1994. The increase of the IR/10,000 dental nurses was smaller: from 43 (95%, CI 26-66) in 1982-1984 to 87 (95% CI 67-111) in 1992-1994. There was no increase in the IR/10,000 cases of irritant dermatoses. The most common causes of allergic contact dermatitis were plastics, disinfectants and antimicrobials, rubber chemicals, and mercury/mercury salts. The most common causes of irritant contact dermatitis were detergents, wet and dirty work, plastic chemicals and antimicrobials. Currently, Finnish dentists have the highest risk and dental nurses have the 4th highest risk of any occupation for developing occupational allergic contact dermatitis: the risk was 6.4-fold (SRR 6.4) in dentists and 6.1-fold in dental nurses, as compared to the general working population. It is evident that safer acrylics and protective gloves, better product declarations and material safety data sheets, as well as more information about protective measures, including non-touch working techniques, are needed.”

“Worldwide, approximately 30-50 millions of people are living in small scale gold mining areas and are primarily burdened by mercury vapour. In the frame of our study, 306 mercury (Hg) vapour burdened adults, working and/ or living in two small scale gold mining areas in Zimbabwe and Tanzania and 58 volunteers from near-by unburdened communities were medically investigated. In addition, blood, urine and hair samples from each participant were analyzed for mercury. Altogether, 26 anamnestic and 24 clinical signs and symptoms, which may be caused by Hg vapour, were evaluated. Multivariate analysis was performed to investigate the influence of the mercury concentration in the bio-monitors on the evaluated anamnestic and clinical signs and symptoms taking into account age, gender, health status, alcohol consumption, use of pesticides and gasoline sniffing. Out of the resulting correlations between concentration and effect, ROC-curves were calculated to determine best estimates of the cut-off-values in the bio monitors. For the parameters ataxia of gait and sadness cut-off-values of 4.7 and 3.6 microg Hg/g crea in urine were calculated. These values were converted to a rounded LOAEL of 3.5 microg Hg vapour/m(3) air. In analogy to the US EPA Report (U.S. Environmental Protection Agency 1997) and the European Position Paper (Pirrone et al. 2001), uncertainty factors of 30 and 50 were applied, resulting in a proposed reference concentration (RfC) in ambient air of 0.1 microg Hg vapour/m(3) and 0.07 microg Hg vapour/m(3), respectively.”