LAS VEGAS >> Concerned parents directed sometimes angry questions at school and federal officials after the discovery of a small amount of mercury prompted officials to keep more than a thousand students for up to 17 hours at a Las Vegas middle school to screen them for exposure to the neurotoxin.

The session with parents Thursday evening came as authorities investigated if a student brought the substance to Walter Johnson Junior High School on Wednesday, forcing 1,300 students, teachers and first responders to undergo testing by the U.S. Environmental Protection Agency, according to Clark County School District police Capt. Ken Young.

It’s too early to say what sort of charges or discipline could be imposed, he said. No mercury-related illnesses have been reported.

Some parents criticized the lack of information they received and the intensity of the response, but officials said it was important to be sure no one went home contaminated.

The Las Vegas Review-Journal reported that a town hall meeting, originally planned as a forum for parents to ask questions of district, police and EPA officials, instead prompted angry parents to expressed their frustration as they sometimes shouted questions.

“You say you want to address it, but you’re not addressing it,” parent Nicole Watson said. “You’re talking in circles.”

One of the most pressing answers parents sought was where, when and how much of the mercury was found.

Randy Nattis, EPA federal on-site coordinator, said it’s unknown how much spilled. “A very little amount of mercury can go a long way in the way that it vaporizes and gets into the air.”

However, Las Vegas Fire Department spokesman Tim Szymanski said fire crews have described the amount to be about five to 10 drops.

Parents also questioned why, if the mercury spill was small, the screening process took so long.

The paper reported that a father in the crowd, Michael Durkin, shouted that his son came into contact with the mercury on Sept. 2. Durkin expressed concern that his son could have spread the substance through his house.

High levels of exposure can cause mercury poisoning, which has symptoms including muscle weakness and speech, hearing and walking impairment, the EPA’s website says.

After screening, the last people were released at 5 a.m. Thursday, and school was canceled through Friday. When the mercury was discovered at noon Wednesday, automated messages alerted parents.

Hundreds of anxious parents waited outside the school for their children, who slowly trickled out through Wednesday night and into Thursday morning.

Students were quarantined in their classrooms until they were screened but were allowed to use the restroom. They received water, juice and food. First responders also coordinated with parents to deliver medicine to children as needed.

“They were laughing. They were talking. They were really, really upbeat,” Szymanski said of students’ morale. “The kids didn’t complain or seem out of it. I was there really, really late and I was really amazed at their attitude.”

The fire department helped EPA workers conduct the screenings, which took about five minutes per person, though some had to be cleaned and checked multiple times. By 11 p.m. Wednesday, a fourth mercury-sniffing machine was flown in from California to speed up the process, Szymanski said.

It was the largest decontamination response the department has ever handled, he said.

One by one, the 1,200 students were swiped with a wand that checked for mercury residue. They also threw their labeled shoes and backpacks into a garbage bag to be examined separately.

Contaminated students had to be cleaned off, ranging from wipes for their hands, to dipping their feet into a tub of chemical soap, washing their hair and changing into a set of school-provided physical education uniforms.

Everyone was eventually cleared of mercury residue. The level of exposure among the contaminated students was minimal because no one is believed to have ingested it, said Young, the school district police captain.

A teacher initially reported the substance after seeing a group of boys and girls playing with it during a school assembly in the gym. The fire department confirmed the silvery liquid was mercury.

The EPA said it’s still evaluating how to decontaminate the school, which can take up to a week. The agency will check the entire property and screen all of the students’ personal items before they are returned. A town hall meeting is set for Thursday evening to answer questions.

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