People have used mercury for various purposes for thousands of years. Traces of mercury were found in Egyptian tombs as far back as 1500 B.C. The Greeks, Romans, Chinese, and Hindus documented the uses of mercury. Some even speculate that the well-known character of the "Mad Hatter" in Alice in Wonderland was based on the brain disease that commonly affected hat makers, who used liquid mercury to make felt in the late 1800's.
Mercury can be found in the air, water and soil. It exists alone as elemental mercury or in combination with other elements as inorganic and organic mercury compounds.
Elemental mercury occurs naturally in the environment and is a shiny, silver-white odorless liquid. It is primarily used to produce chlorine gas and caustic soda and is also used in thermometers, dental fillings and fluorescent light bulbs. When elemental mercury combines with other elements such as oxygen, chlorine and sulfur, inorganic mercury salts are formed. Inorganic mercury salts are sometimes used in skin-lightening creams, antiseptic creams, disinfectant products and ointments. Organic mercury is formed when elemental mercury combines with carbon and is produced mainly by microscopic organisms in the water and soil.
Although humans cannot create or destroy mercury, most of the mercury found in the environment today is the direct result of human activity. Industrial processes such as coal-fired power plants and waste incinerators release elemental mercury into the air, water and soil. Once mercury enters the streams and oceans, it becomes organic mercury or methylmercury. Small fish feed off of the plant sediment containing methylmercury. These small fish are eaten by larger fish, which are eventually eaten by humans.
Exposure to mercury can occur from breathing contaminated air, ingesting contaminated water and food, Having Dental and Medical Treatments and practicing rituals or hobbies that include mercury. Except in work settings where elemental mercury is used, most of the health risk from mercury exposure is due to methylmercury ingestion from eating contaminated fish.
At very high exposure levels, mercury can cause damage to the brain, kidneys and lungs. It can also cause irritability, personality changes, depression, nervousness, the inability to concentrate, tremors, changes in vision or hearing and memory problems. Fetuses, infants and children are at potentially greater risk because their nervous systems are still developing.
The best way to limit your exposure to mercury from seafood is to be aware of wildlife and fish advisories in your area, limit fish intake to recommended quantities and avoid fish known to be contaminated by mercury. This is particularly important for growing children, pregnant and breastfeeding women and women who may become pregnant. For additional information on advisories and recommendations, please visit our Fish Contamination Page.
Other ways to avoid mercury exposure include the careful handling and disposal of any product containing mercury, including thermometers, fluorescent light bulbs, and older mercury-containing medicines. If you have these products in your home, you can dispose of them through household hazardous waste collection events. For information on these events please contact CLEAN LA at 1-888-CLEAN-LA
Monday - Friday
8:00am - 5:00pm
Tel: (626) 430-9820
County of Los Angeles Public Health
Toxicology & Environmental Assessment Branch