Table 1.

Types of mercuric toxicity.

	Elemental mercury	Methyl mercury	Inorganic mercury
Sources	Fossil fuels, dental amalgams, old latex paint, incinerators, thermometers	Pesticides, fish, poultry	Biological oxidation of mercury, demethylation of methyl mercury by intestinal microflora
Absorption	75–85% of vapor absorbed	95–100% absorbed in intestinal tract	7–15% of ingested dose absorbed and 2–3% dermal dose absorbed in animals
Distribution	Distributed throughout the body, lipophilic, crosses blood-brain barrier and placental barrier, accumulates in brain and kidney	Distributed throughout the body, lipophilic, readily crosses blood-brain barrier as well as placental barrier, accumulates in kidney and brain	Does not cross blood-brain or placental barrier, present in brain neonates, accumulates in kidney
Excretion	Sweat, urine, feces, and saliva	90% excreted in bile, feces, 10% in urine	Sweat, saliva, urine and feces
Reason for toxicity	Oxidation to inorganic mercury	Demethylation to inorganic mercury, generation of free radical, binding to thiols in enzymes and structural proteins	Binding to thiols in enzymes and structural proteins

Adapted from Patrick, 2002