Benefit estimates and other health effects from mercury

By: Amanda Giang

When I’m not in glamorous Geneva, and instead in my much-less-glamorous cubicle in Cambridge, MA, I work on assessing the benefits of reducing mercury emissions. The bulk of these benefits are related to improved health—reviewed in our earlier post. Discussion on the health impacts of mercury normally focus on neurologic effects—and with good reason. These effects often have devastating impacts on the lives of victims, and heavy social and economic costs—even when we’re talking about subtle IQ loss from fetal exposure to methylmercury.

What’s more, we have a large body of scientific evidence that helps us understand these neurologic effects, and that can help guide policy decisions about preventing them. But, focusing on just neurologic effects may not tell the whole story. There may be other—though considerably more uncertain—health effects from mercury exposure that have serious policy implications. A large part of my research is about how to include these uncertain health effects in estimating benefits from reduced mercury emissions.

Of these uncertain effects, cardiovascular impacts may be the most important, and also the least uncertain. A growing body of evidence suggests that there may be a causal relationship between methylmercury and cardiovascular disease (coronary heart disease, heart attacks, increased blood pressure). Scientists still aren’t sure why mercury might promote heart attacks; one hypothesis is that it causes oxidative damage.

A committee convened by the US EPA recently decided that there was enough evidence, at least for heart attacks, to warrant including this health effect in future benefit assessments for mercury regulation.* Taking into account mercury-related heart attacks is important because the “cost” of a heart attack—personal, social, and economic—is very high; particularly if a heart attack leads to a fatality. In one of the first studies to include heart attacks in its calculations of costs and benefits, 80% of the benefits associated with reduced mercury exposure ($8.6 billion/year in the US) were due to reduced heart attacks.

If, through further research, it turns out there is a causal relationship between mercury and heart disease, then this week’s mercury treaty might be even more socially beneficial than countries initially thought. This was the case when the US regulated sulfur dioxide in the 1990s. Originally, the focus during the policy’s development was on environmental benefits from reduced acid rain. However, it later emerged that reducing sulfur dioxide has huge health benefits (an unexpected $70 billion/year!). As the science develops, we’ll see whether this will play out for mercury as well.

* NOTE: In the US, part of the regulation making process involves assessing the costs and benefits of regulation.

One thought on “Benefit estimates and other health effects from mercury

  1. Randall

    Amanda, It was so great to read your recent blog post about assessing the benefits of reducing mercury emissions. Analyzing this aspect of mercury has tremendous value in shaping policy.

    In regards to other health effects caused by mercury… The MERCURY EXPOSURE website hosts many published studies from peer reviewed journals which highlight the effects of mercury vapor. I’ve taken some time to list out various studies that you might find of interest that can be found in the science section of our website.
    http://www.mercuryexposure.info/science/news
    In addition, many items will feature video interviews with the lead researcher who published the study.

    Inorganic mercury levels in Americans rose from 2% to 30% over 6 years (a 900% increase) – (VIDEO)

    Dan Laks analyzed data from the CDC’s National Health Nutrition Examination Survey(NHANES) and found that in the 1999-2000 NHANES survey, mercury was detected in the blood of 2 percent of women aged 18 to 49, that level rose to 30 percent of women by 2005-2006 (a 900% increase) and it was associated with a rise in liver, immune and pituitary dysfunction.

    HEALTH

    The Role of Mercury Toxicity in Hypertension, Cardiovascular Disease and Stroke.

    The overall vascular effects of mercury include increased oxidative stress and inflammation, reduced oxidative defense, thrombosis, vascular smooth muscle dysfunction, endothelial dysfunction, dyslipidemia, and immune and mitochondrial dysfunction. The clinical consequences of mercury toxicity include hypertension, coronary heart disease, myocardial infarction, cardiac arrhythmias, reduced heart rate variability, increased carotid intima-media thickness and carotid artery obstruction, cerebrovascular accident, generalized atherosclerosis, and renal dysfunction, insufficiency, and proteinuria.

    Mercury induced idiopathic dilated cardiomyopathy (VIDEO)

    A number of studies clearly establish that the largest source of nonoccupational Hg exposure for the general population is their dental amalgam fillings. Inordinately high levels of Hg (22,000 times greater than that in control subjects) have been found in the heart tissue of patients with idiopathic dilated cardiomyopathy.

    Mercury dental fillings in 1st trimester linked to cleft palate: odds up fourfold in the first 2 months, 17-fold with multiple fillings.

    A study done in Norway revealed some disturbing findings: Women’s odds of giving birth to an infant with isolated cleft palate were increased about fourfold if they had mercury fillings placed in the first or second month of pregnancy and 17-fold if they had mercury fillings placed in multiple months during the first trimester. A cleft palate is a birth defect that has a slit in the roof of the mouth because it failed to close during the 1st trimester.

    A compilation of studies linking mercury exposure to color vision loss.

    Over the last several decades a wide variety of studies have linked mercury exposure to various visual impairments, most notably color vision loss. Unfortunately the majority of these studies have been done overseas and mercury toxicity is not tested for when being evaluated for color vision loss.

    Three decades of studies overwhelmingly show lichenoid lesions heal in patients who removed their mercury fillings.

    Oral lichenoid lesions (OLL) or lichen-planus-like lesions are often idiopathic (arising spontaneously or from an obscure or unknown cause). Oral lichen planus (OLP) is a chronic inflammatory disease that causes bilateral white striations, papules, or plaques on the buccal mucosa, tongue, and gingivae. Lichen planus is a common disorder of unknown aetiology. It has been proposed that in some cases it represents a form of allergic reaction to the metals contained in dental amalgam, particularly mercury. Three decades worth of studies overwhelmingly show that lichenoid lesions healed in patients who removed their mercury fillings.

    Inorganic Mercury (as from dental amalgam) linked to Alzheimer’s disease (VIDEO)

    Recently published in the Journal for Alzheimer’s Disease was a study that performed a meta-analysis of 106 case-control or comparative cohort studies to associate mercury as a causative factor in Alzheimer’s disease. Noting that the main source of mercury in the human body is dental amalgam (1 – 27 ug a day)”.

    Can mercury’s toxic effects exacerbate the medical condition classified as Alzheimers Disease ? (VIDEO)

    Mercury (as Hg2+) exposure to neurons in culture has been shown to produce three of the widely accepted pathological diagnostic hallmarks of AD. These are elevated amyloid protein, hyper-phosphorylation of Tau, and formation of neurofibillary tangles. The hypothesis is that mercury and other blood-brain permeable toxicants that have enhanced specificity for thiol-sensitive enzymes are the etiological source of AD

    Comprehensive overview of how mercury reproduces the major hallmarks of Alzheimer’s Disease (VIDEOS)

    Mercury has been linked to Alzheimer’s disease by a number of different studies that have accumulated over the last two decades. Watch and listen to published scientists talk about how mercury can cause many of the hallmarks of Alzheimer’s disease. This article was taken from the IAOMT’s Petition For Reconsideration, which prompted the FDA to re-evaluate their 2009 ruling that amalgam was safe for everyone.

    Involvement of environmental mercury and lead in the etiology of neurodegenerative diseases

    This experimental neurotoxicology study indicates a potential pathogenic role of lead and mercury in the development of neurodegenerative diseases. Mercury has been shown to interfere with a multitude of intracellular targets, thereby contributing to several pathogenic processes typical of neurodegenerative disorders, including mitochondrial dysfunction, oxidative stress, deregulation of protein turnover, and brain inflammation.

    Mercury in the Spinal Cord After Inhalation of Mercury

    Inhalation experiments in rats and primates show deposition of Hg in spinal cord following single high-dose short-time exposure. Mercury accumulation in anterior horn cells is followed by axonal atrophy and distal weakness similar to the clinical picture in human ALS. Respiratory Hg exposure could contribute to elevated concentrations of Hg found in cerebrospinal fluid from patients with ALS.

    CPOX4 modifies mercury neurotoxicity in children

    The present studies demonstrate significant adverse effects on neurobehavioral functions associated with chronic Hg exposure and the CPOX4 genetic variant among children, with effects manifested predominantly among boys. These findings are the first to describe a genetic polymorphism that modifies the effects of Hg exposure on neurobehavioral functions in children, and suggest directions for future research to define mechanisms underlying differential sensitivity to mercury between boys and girls.

    Gender Differences in the Uptake of Inorganic Mercury by Motor Neurons

    Gender differences have been noted in the tissue distribution of mercury. We sought to determine if the uptake of low-dose inorganic mercury into motor neurons dilifers between male and female mice. In conclusion, female mice take up more inorganic mercury into their motor neurons than do male mice. This may be related to a smaller deposition of mercury in the female kidney. leaving more circulating mercury available to be taken up by motor axons.

    Chronic inorganic mercury induced peripheral neuropathy

    A patient with inorganic mercury intoxication had developed a slowly progressive generalized paralysis of all limbs. Electrophysiologic studies revealed axonal polyneuropathy involving both motor and sensory fibers. Sural nerve biopsy demonstrated axonal degeneration with demyelination and a predominant loss of large myelinated fibers.

    Gender differences for associations between circulating levels of metals and coronary risk in the elderly

    We investigated whether circulating levels of metals related differently to coronary risk in men and women. Hg, Pb and Zn levels were significantly higher in men. The most striking finding is that Hg levels were positively related to LDL and inversely to HDL, suggesting an important role of Hg in determining an atherogenic lipid profile.

    Low mercury concentrations cause oxidative stress and endothelial dysfunction in arteries

    The functional integrity of endothelium is crucial for the maintenance of blood flow and antithrombotic capacity. Vascular endothelium is highly sensitive to oxidative stress, and this stress is the main cause of the endothelial dysfunction observed in cardiovascular diseases. Chronic exposure to low concentrations of mercury promotes endothelial dysfunction. These findings offer further evidence that mercury, even at low concentrations, is an environmental risk factor for cardiovascular disease.

    More than 26 million Americans have chronic kidney disease and most don’t know it.

    From The National Kidney Foundation: according to investigators at Johns Hopkins and Tufts-New England Medical Center, a study based on the National Health and Nutrition Examination Survey estimated that there are 26,000,000 adults with evidence of kidney disease in the USA alone and most are completely unaware of their condition.

    Oxford Journal of Occupational Medicine “Mercury and the Kidney”

    A study published in the Journal of Occupational Medicine in 2010 revealed that The kidney retains more mercury than any other organ in the body and Estimation of urinary mercury concentration is of limited value in the diagnosis of mercurialism, as high excretion rates may be seen without clinical disorder, or mercurialism may be present when urinary excretion is low.

    A comprehensive overview of the connection between dental mercury fillings and antibiotic resistances.

    Installing dental amalgam restorations into laboratory animals resulted in a sharp increase in the proportion of their GI tract (oral and fecal) bacteria able to produce volatile Hg(0). Although the lab animals were never exposed to antibiotics >80% of these mercury transforming bacteria were also resistant to several antibiotics because selection for the mercury transformation genes results in co-selection for whatever antibiotic resistances happen to be on the same plasmid (they are genetically linked)

    A comprehensive overview of the connection between dental mercury fillings and antibiotic resistances

    Installing dental amalgams into monkeys resulted in a sharp increase in the proportion of their GI tract (oral and fecal) bacteria able to produce volatile Hg(0). >80% of these mercury transforming bacteria were also resistant to several antibiotics because selection for the mercury transformation genes results in co-selection for whatever antibiotic resistances happen to be on the same plasmid; they are genetically linked.

    Dental mercury amalgam fillings associated with a deterioration of high-frequency auditory acuity.

    Hearing loss is by far the most common disorder of the senses, affecting more than 36 million people in the US alone. Mercury has been shown to affect the auditory system at a wide range of levels, from the cochlea to the cortex. In this study, we compared the number and surface area of different types of dental fillings with auditory thresholds in the range of .25 to 16 kHz. having more amalgam fillings was associated with a deterioration of high-frequency auditory acuity (8 kHz and above), independent of socio-economic factors. Thus, these results suggest a detrimental, dose-dependent effect of amalgams on hearing. There is also a likely duration-dependent effect.

    A systematic review of mercury ototoxicity

    All the articles analyzed here showed that mercury exposure is ototoxic, inducing peripheral and/or central hearing loss. It is a consensus in the literature that acute and long-term exposure produces irreversible damage to the central auditory system. Measuring mercury levels with biomarkers was unable to predict the relationship between the degree of mercury poisoning and the degree of damage to the auditory system.

    Evidence that Mercury from Dental Amalgam May Cause Hearing Loss in Multiple Sclerosis Patients

    This study was undertaken to determine hearing sensitivity changes of MS subjects after the removal of silver dental fillings. Because of mercury’s known ability to damage hearing, before and after hearing tests were performed on the subjects. Because all frequencies showed an improvement after amalgam removal, it was concluded that (mercury induced) nerve damage was causing the hearing loss.

    Overview of mercury as a potential causal factor of Multiple Sclerosis

    Multiple Sclerosis (“MS”) was first commonly identified in the 19th century during the time in which mercury/silver fillings came into common use. There is toxicological evidence that mercury poisoning victims and multiple sclerosis victims share similar symptoms. While genetic variability and individual ability to excrete mercury probably plays a role, the causation of MS is probably multi-factorial. Very serious consideration should be given to mercury possibly playing a role in the etiology of MS.

    Serum Mercury Level and Multiple Sclerosis

    Exposure to heavy metals has been associated to a higher incidence of multiple sclerosis. We present a possible relationship between serum mercury levels and development of multiple sclerosis. Serum mercury level in MS patients was significantly higher than controls. Concerning all MS patients, serum mercury value was significantly higher than the mercury concentration founded in control subjects. It may reveal that high mercury levels in serum might help MS development in susceptible individuals.

    A comparison of mental health of multiple sclerosis patients with silver mercury dental fillings and those with fillings removed

    In this study, people with amalgam suffered more symptoms such as depression, anger, hostility, psychotism, and were more obsessive-compulsive than the patients with such fillings removed. These data suggested that the poorer mental health status exhibited by multiple sclerosis subjects with dental amalgam fillings may be associated with mercury toxicity from the amalgam.

    Evidence that mercury from silver dental fillings may be an etiological factor in multiple sclerosis

    This paper investigates the hypothesis that mercury from silver dental fillings (amalgam) may be related to multiple sclerosis (MS). It compares blood findings between MS subjects who had their amalgams removed to MS subjects with amalgams. A health questionnaire found that MS subjects with amalgams had significantly more (33.7%) exacerbations during the past 12 months compared to the MS volunteers with amalgam removal.

    The role of environmental factors in autoimmune thyroiditis

    Environmental factors can play an important role in the development of autoimmune thyroiditis (AT) and other autoimmune diseases. This article reviews the role of heavy metals and infectious agents in AT. Memory T lymphocytes can be used as biomarkers of susceptibility to mercury and other inflammation triggers in individual patients. If metal allergy is found, the patient should avoid all exposure to the allergenic substance. Mercury-allergic patients may benefit from replacement of dental amalgam.

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