a couple decades of scientific perspectives and findings:
Adverse immunological effects and autoimmunity induced by dental amalgam and alloy in mice.
http://www.fasebj.org/content/8/14/1183.short
"
Dental amalgam fillings are the most important source of mercury exposure in the general population, but their potential to cause systemic health consequences is disputed. In this study, inbred mice genetically susceptible to mercury-induced immune aberrations were used to examine whether dental amalgam may interfere with the immune system and cause autoimmunity."
hehe not sure about the external validity there...
The role of mercury and cadmium heavy metals in vascular disease, hypertension, coronary heart disease, and myocardial infarction
http://www.ncbi.nlm.nih.gov/pubmed/17405690
"Mercury, cadmium, and other heavy metals have a high affinity for sulfhydryl (-SH) groups, inactivating numerous enzymatic reactions, amino acids, and sulfur-containing antioxidants (NAC, ALA, GSH), with subsequent decreased oxidant defense and increased oxidative stress. Both bind to metallothionein and substitute for zinc, copper, and other trace metals reducing the effectiveness of metalloenzymes. Mercury induces mitochondrial dysfunction with reduction in ATP, depletion of glutathione, and increased lipid peroxidation; increased oxidative stress is common. Selenium antagonizes mercury toxicity. The overall vascular effects of mercury include oxidative stress, inflammation, thrombosis, vascular smooth muscle dysfunction, endothelial dysfunction, dyslipidemia, immune dysfunction, and mitochondrial dysfunction. The clinical consequences of mercury toxicity include hypertension, CHD, MI, increased carotid IMT and obstruction, CVA, generalized atherosclerosis, and renal dysfunction with proteinuria. Pathological, biochemical, and functional medicine correlations are significant and logical. Mercury diminishes the protective effect of fish and omega-3 fatty acids. Mercury, cadmium, and other heavy metals inactivate COMT, which increases serum and urinary epinephrine, norepinephrine, and dopamine. This effect will increase blood pressure and may be a clinical clue to heavy metal toxicity. Cadmium concentrates in the kidney, particularly inducing proteinuria and renal dysfunction; it is associated with hypertension, but less so with CHD. Renal cadmium reduces CYP4A11 and PPARs, which may be related to hypertension, sodium retention, glucose intolerance, dyslipidemia, and zinc deficiency. Dietary calcium may mitigate some of the toxicity of cadmium. Heavy metal toxicity, especially mercury and cadmium, should be evaluated in any patient with hypertension, CHD, or other vascular disease. Specific testing for acute and chronic toxicity and total body burden using hair, toenail, urine, serum, etc. with baseline and provoked evaluation should be done."
Mercury exposure from "silver" tooth fillings: emerging evidence questions a traditional dental paradigm
http://www.fasebj.org/content/9/7/504.short
"For more than 160 years dentistry has used silver amalgam, which contains approximately 50% Hg metal, as the preferred tooth filling material. During the past decade medical research has demonstrated that this Hg is continuously released as vapor into mouth air; then it is inhaled, absorbed into body tissues, oxidized to ionic Hg, and finally covalently bound to cell proteins. Animal and human experiments demonstrate that the uptake, tissue distribution, and excretion of amalgam Hg is significant, and that
dental amalgam is the major contributing source to Hg body burden in humans. Current research on the pathophysiological effects of amalgam Hg has focused upon the immune system, renal system, oral and intestinal bacteria, reproductive system, and the central nervous system. Research evidence does not support the notion of amalgam safety."
Amalgam studies: Disregarding basic principles of mercury toxicity
http://www.sciencedirect.com/science/ar ... 3904703028
"Dental amalgam, which has been used for over 150 years in dental practice, consists of about 50% metallic mercury. Studies on animal and humans show that mercury is continuously released from dental amalgam and absorbed by several body tissues.
It is widely accepted that the main source of mercury vapor is dental amalgam and it contributes substantially to mercury load in human body tissues. There is still a controversy about the consequences of this additional mercury exposure from amalgam to human health. Many studies were performed to evaluate possible adverse effects. In this comment, these studies were analyzed with regard to their methodical quality by considering the newest findings on mercury toxicity and metabolism. In sum, a number of studies are methodically flawed drawing inaccurate conclusions as to the safety of dental amalgam."
Mercury amalgam dental fillings: An epidemiologic assessment
http://www.sciencedirect.com/science/ar ... 3906000034
"Dental amalgam fillings containing approximately 50% mercury have been used for almost 200 years and have been controversial for almost the same time. Allegations of effects caused by amalgams have involved many diseases. Recent evidence that small amounts of mercury are continuously released from amalgam fillings has fuelled the controversy. This is a comprehensive review of the epidemiologic evidence for the safety of dental amalgam fillings, with an emphasis on methodological issues and identifying gaps in the literature. Studies show little evidence of effects on general chronic disease incidence or mortality. Limited evidence exists for an association with multiple sclerosis, but few studies on either Alzheimer's or Parkinson's diseases. The preponderance of evidence suggests no renal effects and that ill-defined symptom complexes, including chronic fatigue syndrome, are not caused by amalgams. There is little direct evidence that can be used to assess reproductive hazards. Overall, few relevant epidemiologic studies are available. Most prior assessments of possible amalgam health effects have been based on comparisons of dental mercury exposures with occupational exposures causing harm. However, the amalgam-exposed population contains a broader, possibly more susceptible, spectrum of people. Common limitations of population-based studies of dental amalgam effects include inadequate longitudinal exposure assessment and negative confounding by better access to dental care in higher socioeconomic groups. Better designed studies are needed, particularly for investigation of neurodegenerative diseases and effects on infants and children."
Nephrotoxicity, neurotoxicity, and mercury exposure among children with and without dental amalgam fillings
http://www.sciencedirect.com/science/ar ... 3908000801
"A scientific review panel for the US Food and Drug Administration (FDA) recently identified the need for more data on the health risk of mercury exposure from dental amalgam among susceptible populations. We evaluated impacts of low-level mercury exposure on renal function and neurobehavioral and neuropsychological performance among children.
Dental histories for 403 children aged 7–11 years in five schools from Xuhui, Shanghai were checked by dentists. Of them, 198 with confirmed amalgam fillings were recruited (exposure group). Reference children (N=205) were those who never had dental amalgam treatment. In May 2004, each child provided a urine sample for measurements of total mercury, N-acetyl-β-d-glucosaminidase activity, microalbumin, and creatinine (Cr). The Child Behavior Checklist, Eysenck Personality Questionnaire, and an intelligence screening test were administered.
The geometric mean urinary mercury concentration was 1.6 μg/g Cr for children with and 1.4 μg/g Cr for children without amalgam fillings. No differences were found between children with and without fillings for either renal function biomarker, or on neurobehavioral, neuropsychological, or intelligence tests.
Although urinary mercury concentration was slightly elevated among children with amalgam fillings, we found no evidence of adverse effects on the outcomes evaluated. These results agree with those from recent trials in developed countries."
Mercury exposure and risks from dental amalgam in the US population, post-2000
http://www.sciencedirect.com/science/ar ... 9711006607
"Dental amalgam is 50% metallic mercury (Hg) by weight and Hg vapour continuously evolves from in-place dental amalgam, causing increased Hg content with increasing amalgam load in urine, faeces, exhaled breath, saliva, blood, and various organs and tissues including the kidney, pituitary gland, liver, and brain. The Hg content also increases with maternal amalgam load in amniotic fluid, placenta, cord blood, meconium, various foetal tissues including liver, kidney and brain, in colostrum and breast milk.
Based on 2001 to 2004 population statistics, 181.1 million Americans carry a grand total of 1.46 billion restored teeth. Children as young as 26 months were recorded as having restored teeth. Past dental practice and recently available data indicate that the majority of these restorations are composed of dental amalgam.
Employing recent US population-based statistics on body weight and the frequency of dentally restored tooth surfaces, and recent research on the incremental increase in urinary Hg concentration per amalgam-filled tooth surface, estimates of Hg exposure from amalgam fillings were determined for 5 age groups of the US population.
Three specific exposure scenarios were considered, each scenario incrementally reducing the number of tooth surfaces assumed to be restored with amalgam. Based on the least conservative of the scenarios evaluated, it was estimated that some 67.2 million Americans would exceed the Hg dose associated with the reference exposure level (REL) of 0.3 μg/m3 established by the US Environmental Protection Agency; and 122.3 million Americans would exceed the dose associated with the REL of 0.03 μg/m3 established by the California Environmental Protection Agency.
Exposure estimates are consistent with previous estimates presented by Health Canada in 1995, and amount to 0.2 to 0.4 μg/day per amalgam-filled tooth surface, or 0.5 to 1 μg/day/amalgam-filled tooth, depending on age and other factors."
Mercury (Hg) burden in children: The impact of dental amalgam
http://www.sciencedirect.com/science/ar ... 9711004359
"The risks and benefits of using mercury (Hg) in dental amalgam have long been debated. This study was designed to estimate Hg body burden and its association with dental amalgam fillings in 182 children (ages: 5–15 years) living in Taif City. Hg was measured in urine (UHg), hair (HHg) and toenails (NHg) by the Atomic Absorption Spectrophotometer with Vapor Generator Accessory system. Urinary Hg levels were calculated as both micrograms per gram creatinine (μg/g creatinine) and micrograms per liter (μg/L). We found that children with amalgam fillings (N = 106) had significantly higher UHg-C levels than children without (N = 76), with means of 3.763 μg/g creatinine versus 3.457 μg/g creatinine, respectively (P = 0.019). The results were similar for UHg (P = 0.01). A similar pattern was also seen for HHg, with means of 0.614 μg/g (N = 97) for children with amalgam versus 0.242 μg/g (N = 74) for those without amalgam fillings (P = 0). Although the mean NHg was higher in children without amalgam (0.222 μg/g, N = 61) versus those with (0.163 μg/g, N = 101), the relationship was not significant (P = 0.069). After adjusting for many confounders, the multiple logistic regression model revealed that the levels of UHg-C and HHg were 2.047 and 5.396 times higher, respectively, in children with dental amalgam compared to those without (P < 0.01). In contrast, a significant inverse relationship was seen between NHg levels and dental amalgam fillings (P = 0.003). Despite the controversy surrounding the health impact of dental amalgam, this study showed some evidence that amalgam-associated Hg exposure might be related with symptoms of oral health, such as aphthous ulcer, white patches, and a burning-mouth sensation. Further studies are needed to reproduce these findings. The present study showed that significant numbers of children with or without amalgam had Hg levels exceeding the acceptable reference limits. The detrimental neurobehavioral and/or nephrotoxic effects of such an increased Hg on children should be a cause of concern, and further investigation is warranted. Our results are alarming and indicate an urgent need for biomonitoring and assessment of exposure. Changes in dental practices involving amalgam, especially for children, are highly recommended in order to avoid unnecessary exposure to Hg."
Mercury in serum predicts low risk of death and myocardial infarction in Gothenburg women
http://link.springer.com/article/10.100 ... 012-0746-8
"We assessed the association between serum Hg (S–Hg) and risk of cardiovascular disease in a prospective population-based cohort, with attention to the roles of dental health and fish consumption. ... There was a strong inverse association between Hg exposure and CVD. Likely, reasons are confounding with good dental health (also correlated with the number of amalgam fillings in these age groups) and/or fish consumption. The results suggest potential effects of dental health and/or fish consumption on CVD that deserve attention in preventive medicine."
Neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal dental amalgam: The Seychelles Child Development Nutrition Study
http://www.sciencedirect.com/science/ar ... 6213001724
We measured prenatal maternal amalgam status as a metric of mercury vapor exposure.
We administered age appropriate neurodevelopmental tests to the children at 5 years.
Prenatal mercury vapor exposure was not associated with any outcome.
We found no evidence that maternal amalgams harm children's neurodevelopment.
i'd be interested to read the science on the seafood contribution, if you have some links. some of the studies above assert that amalgam is widely accepted as the major source of Hg exposure and loading in humans. (i went back and highlighted these). i'll certainly agree, as a fan of science, that in general it's better to back up claims with academic literature - fosters a better tone for the debate