Mercury

PHYSIOLOGIC EFFECTS:

A major proportion of absorbed mercury accumulates in the kidneys, neurological tissues, and liver.

Molecular mechanisms of toxicity involve oxidative stress. Once in a cell, Hg depletes intracellular antioxidants and therefore causes mitochondrial dysfunction.

Mercury releases intracellular calcium, disrupting neuronal transport, alters cell membrane integrity, interrupts microtubule formation, disrupts or inhibits enzymes, inhibits protein and DNA synthesis and impairs immune function.

Methyl mercury (organic) appears to be absorbed almost completely in the GI tract, and in this form is higher in the brain compared to other forms. It is excreted fecally and can be measured in blood; urine is not a reliable indicator of organic mercury.

Inorganic mercury accumulates in the kidneys. It is excreted in the urine and both inorganic and elemental Hg can be measured in urine and blood.

Blood and urine mercury levels correlate fairly well with each other, but not with total body burden; blood and urine mercury reflects recent exposure.

CLINICAL SIGNIFICANCE:

GI symptoms, neurotoxicity (headaches, tremor, decreased mental concentration), and nephrotoxicity are common, as well as iron deficiency.

Inhaling elemental Hg vapors causes acute symptoms including cough, chills, fever, shortness of breath, nausea, vomiting, diarrhea, metallic taste, dysphagia, salivation, weakness, headaches and visual disorders. Chronic inhalation may cause cognitive impairment and personality changes.

SOURCES:

Mercury (Hg) has three forms:

Elemental (metallic)- older glass thermometers, fluorescent light bulbs, dental amalgams, folk remedies, combustion, electrical industry (switches, batteries, thermostats), solvents, wood processing

Organic (methyl mercury)- seafood, thimerosal (preservative), fungicides

Inorganic- skin lightening compounds, industrial exposure, folk medicine, lamps, photography, disinfectants