A Nevada middle school will remain closed at least through week's end as hazardous materials crews clean it of mercury contamination and federal health experts join a review of potential dangers, officials said Wednesday.
Pau-Wa-Lu Middle School, 50 miles south of Reno in Douglas County, was locked down before noon Tuesday and then closed after one student brought about a quarter cup of the toxic metal to school and shared it with classmates.
Several students handled the mercury on the bus ride to school and the substance was spilled in several areas on campus.
Douglas County School Superintendent John Soderman said a preliminary analysis shows the gymnasium, cafeteria and at least two of the school's five classroom pods were contaminated.
He said the school will remain closed at least through Friday as clean up work continues.
About 60 children exposed to the mercury were isolated from other classmates Tuesday and decontaminated - a procedure that involved a shower and change of clothes.
Their possessions - back packs, books and clothing - were confiscated and sealed in bags until they can be tested, said Lisa Fasano, a spokeswoman for the U.S. Environmental Protection Agency, which sent an emergency response team to the site late Tuesday.
State and federal environmental and health experts said there's little risk the children will suffer any ill effects from the exposure.
"We don't believe anybody to be in imminent danger of a health risk," Soderman said at a news conference Wednesday.
Dr. Brad Lee, Nevada's state health officer, agreed.
"The likelihood of things happening from this spill is very remote," he said.
Still, Lee said local physicians and emergency rooms were alerted to the spill as a precaution Tuesday so they would be aware to look for symptoms of mercury poisoning in their patients.
The National Centers for Disease Control also was notified and is sending investigators to monitor any biological effects from the spill, should they occur, he said.
Notices were also sent home with students to their parents advising them of the dangers and symptoms of mercury poisoning, Soderman said.
Officials said it was unclear where or how the student obtained the mercury.
Douglas County Sheriff's Sgt. Tom Mezzetta said the youth, who was not identified, was interviewed by investigators and a report will be forwarded to the district attorney's office for review.
Mezzetta said the youth could face possible charges in juvenile court for reckless endangerment if it's determined he was aware of the risks the mercury posed to others.
Safety Kleen, a private contractor in Sparks, is conducting the cleanup at the school, Soderman said.
Steve Calanog, a member of the EPA response team, said sensitive monitoring equipment is being used to test the air quality and the building itself for contamination levels as the cleanup process continues.
At room temperature, mercury emits vapors that can be inhaled and potentially reach the brain, according to an EPA fact sheet. It also can be absorbed through the skin.
Exposure to high levels of elemental mercury vapor can result in nervous system damage, including tremors, and mood and personality alterations, the EPA said.
As the cleanup proceeds, Calanog said the temperature in the building will be raised and new readings taken until they meet acceptable standards.