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CAS No. 7439-97-6 (metal)

Mercury (Hg) is a naturally occurring metal. Metallic mercury is a shiny, silver-white, odorless liquid. When heated it becomes a colorless, odorless gas. Some of the health effects exposure to mercury may cause include: irritation to the eyes, skin, and stomach; cough, chest pain, or difficulty breathing, insomnia, irritability, indecision, headache, weakness or exhaustion, and weight loss. Workers may be harmed from exposure to mercury. The level of exposure depends upon the dose, duration, and work being done.

Mercury is used in many industries. It’s used to produce chlorine gas and caustic soda, and in thermometers, barometers, batteries , and electrical switches.  Some examples of workers at risk of being exposed to mercury include the following:

  • Workers in facilities where electrical equipment is manufactured
  • Workers in fluorescent light bulb (CFL) recycling facilities
  • Workers in facilities where automotive parts are manufactured
  • Workers in chemical processing plants that use mercury
  • Workers in medical, dental, or other health services who work with equipment that contains mercury
  • Dentists and their assistants when breathing in mercury vapor released from amalgam fillings

NIOSH recommends that employers use Hierarchy of Controls to prevent injuries.  If you work in an industry that uses mercury, please read chemical labels and the accompanying Safety Data Sheet for hazard information. Visit NIOSH’s page on Managing Chemical Safety in the Workplace to learn more about controlling chemical workplace exposures.

The following resources provide information about occupational exposure to mercury. Useful search terms for mercury include “colloidal mercury,” “mercury metal,” “metallic mercury,” and  “quicksilver.”

NIOSH Chemical Resources

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NIOSH Pocket Guide

The NIOSH Pocket Guide to Chemical Hazards (NPG) helps workers, employers, and occupational health professionals recognize and control workplace chemical hazards.

Logo of Manual of Analytical Methods.

Manual of Analytical Methods

The NIOSH Manual of Analytical Methods (NMAM) is a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.

Logo of Health Hazard Evaluations consisting of three letters: HHE

Health Hazard Evaluations

The Health Hazard Evaluation Program (HHE) conducts onsite investigations of possible worker exposure to chemicals. Search the HHE database for more information on mercury.

Related NIOSH Resources

Selected Publications

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International Resources