LUBBOCK — Classes were canceled and at least 60 people at a West Texas school were taken to hospitals to be examined after being exposed to mercury when a student brought in about an ounce of the toxic element.Nobody was injured in the incident Tuesday at John B. Hood Junior High School in Odessa, Ector County school district spokesman Mike Adkins said Wednesday. School was closed Tuesday afternoon and Wednesday for air-quality tests. Mercury is a naturally occurring element that can be absorbed through skin and mucous membranes. The poison is most dangerous when heated because vapors can be inhaled. Twenty students handled or touched the silver liquid on tables in the cafeteria and in two classrooms, and about 40 other students and teachers could have gotten secondary exposure by being nearby, Adkins said. The group of students and teachers was quarantined, and they showered before being taken to two area hospitals. “We wanted to make sure any students and staff who were in close proximity were OK,” Adkins said of the 60 people whom doctors cleared of contamination. “There’s just no way to tell how long they’re exposed to it.” The boy who brought the mercury to school, whose age Adkins did not know, could face disciplinary action.