CHICAGO -- Dozens of people in Houston potentially were exposed to the toxic metal mercury after it was spilled outside a Walmart, a Sonic Drive-In and a gas station, officials said. Federal and local investigators were trying to determine if the spills were intentional. Fire Chief Sam Pena said up to 60 people were asked to take decontamination showers and a pregnant woman was taken to a hospital as a precaution.
Here's a closer look at mercury:
WHAT IS MERCURY?
Mercury is a heavy, silvery liquid that occurs naturally in the earth's crust, and is released into the air, water and soil in several forms. It's used in such things as thermometers, batteries, fluorescent light bulbs and dental fillings, though its use has diminished because of concerns about its toxicity. Sources of mercury in the environment include the burning of coal and mining activities.
WHAT ARE THE POTENTIAL HEALTH EFFECTS?
Mercury is a potent neurotoxin, but health effects depend on how much mercury you're exposed to, how long you're exposed and your age. Small children are most vulnerable.
Liquid mercury can change into a gas. Short-term exposure to metallic mercury vapors — such as from spills — can cause lung damage, nausea, vomiting, diarrhea, increased blood pressure and heart rate, skin rashes, and eye irritation. Exposure to high levels can permanently damage the brain, kidneys and developing fetuses.
Bacteria in water and soil can transform mercury into another form, called methylmercury, which builds up in the food chain. Most people are exposed by eating fish contaminated with mercury.
There are blood and urine tests that can measure mercury levels in a person's body.
WHAT IF I SPILL MERCURY?
Emergency officials should be called for any spill greater than the amount found in a thermometer, thermostat or light bulb. A hazardous materials team was called last week to clean up half a cup of mercury found on the basement floor at a water treatment plant in Oswego, New York.
If a small item such as a thermometer or compact fluorescent light bulb breaks, the Centers for Disease Control and prevention says it can be cleaned up by following specific instructions. Any clothing that comes in contact with the liquid should be thrown away. Mercury should not be washed down the drain.
In all cases, all outside windows and doors should be opened, and people and pets should leave without walking through the spill.
In Houston, those who were exposed had to remove their clothes and shoes and take a shower in a tent set up on-site, according to spokesman Cory Stottlemyer of the city's Office of emergency Management. They were then given clothing to leave in.