21.5 OCCUPATIONAL EXPOSURES
Occupational exposure is almost exclusively to inorganic mercury and occurs at chloralkali
plants, mercury mines, thermometer factories, fluorescent light tube production plants,
refineries,andin dental clinics.Highmercuryconcentrationshavebeendescribedfor all these
situations, with considerable variations depending on the working conditions. Some 70,000
workers in the United States were considered exposed to mercury, primarily elemental
mercury, but the number is decreasing. Serious mercury exposures may occur in connection
with gold mining, especially when gold amalgam is heated. In developing countries, this
process is often carried out under field conditions or in small gold vending shops without or
with insufficient ventilation. An estimated 10 million workers in Africa, Latin America, and
Asia are exposed to high concentrations of elemental mercury through such activities. The
impacts on health from these exposures are generally not monitored.