A History of Mercury Poisoning

The Toxic Effects of Mercury

 

Human Health Effects of Methylmercury Exposure

Sergi Díez.  February 2009.  Reviews of Environmental Contamination and Toxicology.  198:111-32.  Source (1)

Sergi Díez

Hg   -   Mercury toxicity   -   Mercury ingestion   -   Thimerosal   -   Mercury poisoning   -   Acute mercury poisoning   -   Chronic mercury poisoning   -   norganic mercury exposure   -   Organic mercury exposure   -   Elemental mercury exposure   -   Inorganic mercury salt exposure   -   Mercury salts   -   Methyl mercury   -   Methylmercury   -   Acrodynia   -   Pink    disease   -   Acrodynic erythema   -   Dermatopolyneuritis   -   Erythredema   -   Swift('s) disease   -   Hydrargyria   -   Hydrargyrism   -   Mercurialism

Sergi Díez

Mercury (Hg) toxicity  - Mercury has profound cellular, cardiovascular, hematological, pulmonary, renal, immunological, neurological, endocrine, reproductive, and embryonic toxicological effects.(1)  Mercury body burden has also been associated with or implicated in a number of immune or autoimmune conditions including arthritis,  rheumatoid arthritis, schizophrenia, allergic disease, amyotrophic lateral sclerosis, autoimmune thyroiditis, autism/attention deficit hyperactivity disorder, eczema, epilepsy, psoriasis, multiple sclerosis, scleroderma, and systemic lupus erythematosus. (8)

Kids are more prone to the toxic effects of heavy metals.  Infants and young children are far more sensitive as the rapidly developing body systems in the fetus, infants and young. Childhood exposure to some metals can result in learning difficulties, memory impairment, damage to the nervous system, and behavioral problems such as aggressiveness and hyperactivity. At higher doses, heavy metals can cause irreversible brain damage. Children may receive higher doses of metals from food than adults, since they consume more food for their body weight than adults.(2)

  • The half life of mercury in the brain is 18 to 30 years
  • Half-life' of mercury in human body is about 70 days
  • Produces inflammatory reactions in the kidney
  • In humans, mercury poisoning results in inhibition of endocrine function, atherosclerosis, cardiac effects such as hypertension
  • Hg0 and MeHg accumulate in the central nervous system (CNS) and are neurotoxic, whereas the inorganic Hg salts are nephrotoxic
  • In severe cases such as in Minamata and Niigata (Japan), and the Wabigoon-English River system (Ontario, Canada), mercury poisoning can result in fetal death, neurological disorders resembling cerebral palsy, deafness, and visual impairment.
  • Kawasaki disease - Exposure to inorganic Hg can also induce Kawasaki disease in children which results from a weakening of the immune system
  • Minamata Disease - Caused by the release of methylmercury from the Chisso Corporation's chemical factory from 1932 to 1968.  Mercury sulphate in the wastewater was metabolized to methylmercury by bacteria in the sediment

 

Three Forms of mercury:

1.  Elemental Mercury  Hg0 metallic mercury/mercury vapor and or quicksilver.  Health effects (3)

  • mercury vapor (Hg0) from dental amalgam restorations [3]
  • Historically, dental amalgam is one of the most commonly used tooth fillings. (1, 2) It is made of two nearly equal parts:
    1.  Liquid mercury
    2.  A powder containing silver, tin, copper, zinc and other metals
  • Mercury released from dental amalgams ranges from 9 to 17 mg/day
  • Autopsy studies show that dental amalgams are a source of mercury in human tissue - typically 2 to 12 times more mercury compared to individuals without dental amalgams
  • primary target organs of elemental mercury are the brain and kidney
  • mercuric oxide (HgO) diffuses readily and is lipid soluble and easily crosses the blood-brain barrier and lipid bilayers of cells and cell organelles such as mitochondria
  • from ingestion is poorly absorbed with a bioavailability of less than 0.01%

2.  Organic Mercury such as methylmercury [CH₃Hg]⁺ and ethyl mercury [C2H5Hg]

  • exposure in the general population are methylmercury (MeHg) from seafood.  Methyl/etheyl mercuries can be absorbed by the human gut and skin
  • In addition to methylmercury, there are a numberof other organomercurials to which humans might be exposed:
  • 1.  Dimethylmercury, is notoriously toxic, but found use as an antifungal agent and insecticide
  • 2.  Merbromin and phenylmercuric borate are used as topical antiseptics
  • 3.  Nitromersol is used as a preservative for vaccines and antitoxins.
  • 4.  Thiomersal is a compound containing ethyl mercury used to prevent bacterial and fungal growth in some inactivated vaccines in multi-dose vials.
  • Human body lacks a mechanism to excrete organometallic mercury
  • Methylmercury is a neuro toxin causing damage to the cental nervous system (CNS).  It accumulates in the liver, brain, kidney.

3.  Inorganic Mercury (Hg+ and Hg2+)

  • exposure in the general population include vegetables, grains (7) and soils from areas surrounding coal-fired power plants. (6)
  • found in foods with high levels of high fructose corn syrup (4),
  • are water soluble with a bioavailability of 7% to 15% after ingestion; they are also irritants and cause gastrointestinal symptoms.(4)
  • it reacts quickly with intracellular molecules such as enzymes, glutathione etc, thus inhibiting the actions of these molecules and affecting normal cellular functions.  Even at very low concentrations, it decreases levels of glutathione (GSH) in cells.  GSH is a powerful antioxidant in cells and thereby increases oxidative stress
  • kidney, is the main site of accumulation which produces inflammatory reactions in the kidney
  • is excreted via urine and feces, sweat, tears and breast milk.

 

The Largest Public Health Burden is Not Toxicity but the Loss of Immune Tolerance

study recently published in the journal Environmental Health Perspectives illustrates this in the case of mercury exposure among females of reproductive age. The authors state (2):

“Autoimmunity, which can include autoantibody formation, represents a breakdown of tolerance against self-antigens. Self-reactive lymphocytes may occur in healthy individuals, and in the absence of related pathology, autoimmunity represents pre- or sub-clinical immune dysregulation. Thus, the term autoimmunity should be distinguished from autoimmune disease, as it does not denote clinical or symptomatic disease…autoantibodies may precede autoimmune diagnoses by several years, and nearly all autoimmune diseases are characterized by circulating autoantibodies.  Antinuclear antibodies (ANAs) are highly sensitive for a variety of autoimmune conditions, including systemic lupus erythematosus (SLE), scleroderma, and Sjögren’s syndrome.”

Dr. Jonathan Miller

The Toxic Effects of Mercury

Exposure to inorganic mercury can also induce Kawasaki disease in children which results from a weakening of the immune system.  Exposure to some metals, such as mercury and lead, may also cause development of autoimmunity, in which a person's immune system attacks its own cells. This can lead to joint diseases such as rheumatoid arthritis, and diseases of the kidneys, circulatory system, and nervous system.(2) 

Image and video source: Kawasaki Disease: A Parents Guide


The Selenium-Mercury link

Selenium is an essential trace element and it is necessary to achieve the activity of the 25-30 selenoenzymes that are required to protect the central nervous system and the brain from oxidative damage.  High MeHg levels bind selenium by irreversibly inhibiting selenoenzyme activity, with detrimental affects.  However, a diet rich in selenium (present in many foods, including fish), may replenish MeHg-bound selenium, thereby protecting the activity of brain cells.

Heavy Metal Testing