Mercury in Local Waterways
What is mercury?
Mercury is a heavy metal commonly found in items such as thermostats, thermometers, fluorescent lights, some cosmetics, certain car parts, batteries and more. Mercury has been used for industrial processing, mining, treatment of hides, and even for medical purposes. For a more complete list see Mercury in Consumer Products | US EPA Mercury doesn’t break down; it lasts for centuries in the environment.
Why is mercury toxic?
A process called Methylation, changes inorganic mercury to organic mercury (methylmercury). Most mercury is atmospherically deposited through the air as inorganic mercury. This inorganic mercury can interact with other compounds by movement through the atmosphere and become methylmercury through a complicated chemical process. Methylmercury can bind with soil which is carried to streams through erosion. Organisms such as algae ingest mercury and in turn are consumed by fish. The heavy metal is then consumed by species higher on the food chain, including humans. Methylmercury is the most common organic mercury compound found in the environment, and is highly toxic. This substance is retained in fat and muscle tissue of fish, shellfish, humans, and other organisms.
The Oregon Health Authority maintains fish consumption advisories. In general, healthy adults should eat no more than 4 meals of native fish per month. Click here for more information on the Oregon health Authority Advisories and Guidelines.
The Mercury Story
Many people know not much more about mercury than it’s what we see in a thermometer However, historically, mercury has been used to purify gold, make paint, and treat felt. The phrase ‘mad as a hatter’ came about because hat makers used to show signs of dementia from the pelts used to make hats.
Today people are more aware that mercury is toxic, which has led to regulations about its use. In the United States, mercury is still used in some thermostats, thermometers, laptop screen shutoff switches, pressure switches, old doorbells, and fluorescent lightbulbs. The amount of mercury in these items is small, but it is important to know how to properly dispose of them and cleanup spills if they should occur.
When it comes time to dispose of mercury-containing items, click here for Polk County Resources. Fluorescent tubes can also be taken to Lowes or Home Depot. If you accidentally break something that contains less than 3 tablespoons of mercury, follow the DEQ’s guidelines for cleanup. If you spill more than that, do not try to clean it up by yourself. Call the Oregon Response System at 1-800-452-0311 or 503-378-6377.
If mercury-containing items are not properly disposed of, the mercury can find its way into our waterways. When mercury gets into water, naturally-occurring bacteria turn it into a toxin called methylmercury. This toxin is especially hazardous because when an animal ingests it, the mercury is absorbed into the body tissue. If that animal gets eaten, the predator will then absorb that same mercury into its tissues. In this way, mercury will accumulate up the food chain so that large, predatory fish contain much more mercury than their smaller prey.
When people eat too much fish with high levels of mercury, it can damage our brains, hearts, and kidneys. This is especially true for children whose bodies are still growing. Symptoms of mercury poisoning include lack of coordination, vision changes and difficulty speaking.
