Sources and Causes of Mercury in the Environment

A supply of clean water is something that many of us take for granted.  Often, when water looks clean, we think it is fine to drink.  Contaminants may be visible and make water cloudy, or have a noticeable odor or taste.  Others are not perceptible, but they can have harmful health effects.  Mercury is one contaminant that is undetectable but may be present in our waters.  There are currently about thirty water bodies in Washington State that do not meet water quality standards for mercury.

Mercury occurs naturally in the environment as well as through industrial and man-made (anthropogenic) pollution. 

Human-caused sources of mercury far outweigh natural sources of mercury.  Products containing mercury which are thrown in the garbage or washed down sinks and drains end up in landfills, incinerators, or sewage treatment facilities.  Mercury from these products can leach into the ground and groundwater.  Mercury may be directly released into the environment, or through combustion (burning) activities, from coal-fired power plants, where it is released in fine particles in the air that fall to the earth in rain droplets or snowflakes.

Once released into the environment, mercury eventually ends up in the water, settled into sediments.  Bacteria in the water converts the inorganic mercury into methylmercury, an organic mercury compound.  Mercury enters the food chain from all mercury sources.  The mercury-containing bacteria are eaten by plankton and other small creatures, which in turn are eaten by small fish, then larger fish, and so on.  Because mercury does not easily leave the body of an organism, the amount of mercury builds in species as they go up the food chain in a process called biomagnification.  Predatory fish, which sit higher up on the food chain and are long-lived, can accumulate hundreds of thousands to millions of times the concentration of mercury that originally entered the water. 
 

As people eat mercury-tainted fish, the mercury is transferred to humans and builds up in the body.  Bioaccumulation presents its greatest threat to pregnant women, unborn babies and young children.  Developing fetuses and babies are developing their neurological systems which are particularly susceptible.

Learn more about how to choose fish that are lower in mercury by visiting our Fish Facts Web site.

You Can Make a Difference!

Did you know each year, about 3,800 to 5,000 pounds of mercury are released into Washington’s environment? By taking personal action to minimize the quantity of mercury you release into our environment, you can help protect your own health and that of your family.  Take part, and you will be an environmental steward helping to protect us all.
 

Health Risks What You Can Do What Washington is Doing List of Products Containing Mercury