School and state environmental officials planned to work through the night Wednesday cleaning up what appears to be an intentional mercury spill at Carson High School. They decided at about 11 p.m. Wednesday to close school today.
A blood pressure machine that uses mercury to gauge pressure spilled about 6 milliliters of the toxic element onto the floor of the nurse's office Wednesday, possibly contaminating at least 18 students and eight staff members, said Mike Mitchell, director of operations for the Carson City School District.
Sheriff Kenny Furlong said late Wednesday night a cap that keeps the mercury in the container appeared to have been intentionally removed and mercury forced out.
"Detectives will be investigating the incident as a crime," he said.
Mitchell said they want to take a day to make sure the school is cleaned.
"The abatement team is doing a great job but we're not comfortable about having it 100 percent clean by 7 a.m. The process is you have to clean and test it, clean and test it," Mitchell said.
Mitchell said the nurse noticed the spill about 11 a.m., just 90 minutes before the school's 2,526 students were set to leave classes early to accommodate teacher staff meetings.
The Carson City Fire Department's Hazardous Material Team, with the help of the Environmental Protection Agency, conducted the decontamination of students and staff known to have visited the nurse's office, said firefighter Tom Raw, decontamination leader.
Raw said each person was asked to remove clothing and jewelry then was tested with an air analysis instrument called a "sniffer."
Those shown to be contaminated by mercury were asked to shower with regular soap and water in the school's gym locker room. They were free to go if the sniffer was unable to detect any more mercury on them.
"The kids are very cooperative and level-headed. They are doing a great job with it," Assistant Fire Chief Bruce Van Cleemput said.
School Superintendent Mary Pierczynski said parents were called to pick up their children once they were cleared by the fire department.
According to Raw, the seized items would be tested and decontaminated later.
"We knew the spill was isolated to the nurse's room, so we immediately had the air-handling system shut down and denied entry into the contaminated area. We'll need to do more investigation into whether or not it has been moved by bodies throughout the school," Raw said.
Van Cleemput said the EPA will examine the building and, if contamination is found, a cleanup company from Reno will clean the area.
Exposure to high levels of elemental mercury vapor can result in nervous system damage, including tremors and mood and personality alterations, the EPA said.
In January 2004, Pau-Wa-Lu Middle School in Douglas County was closed for two weeks as state and federal hazardous materials experts checked air quality and surroundings for contamination after one youngster brought a vial of mercury to school.
Douglas County officials estimated $100,000 was spent on the cleanup, including $50,000 for 1,700 square yards of carpet that was removed.
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Forms of mercury: Mercury is a naturally occurring element that is found in air, water and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds.
Sources of mercury: Mercury is an element in the earth's crust. Humans cannot create or destroy mercury. Pure mercury is a liquid metal, sometimes referred to as quicksilver that volatizes readily. It has traditionally been used to make products like thermometers, switches and some light bulbs.
Exposure to mercury: Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others. The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain.
Another less common exposure to mercury that can be a concern is breathing mercury vapor. These exposures can occur when elemental mercury or products that contain elemental mercury break and release mercury to the air, particularly in warm or poorly ventilated indoor spaces.
Health effects of mercury: Mercury exposure at high levels can harm the brain, heart, kidneys, lungs and immune system of people of all ages.
Source: Environmental Protection Agency