A statement Sunday evening from the Dallas Independent School District said the mercury "was brought to school by a student who found a container of it near his/her home."
Three children, siblings, were hospitalized after they showed symptoms of fever and a rash, The Dallas Morning News reported Monday, adding they brought the mercury to Urban Park Elementary School Oct. 17 after playing with it at home for several days, and spilled it at the school while their mother was on the campus attending a parent-teacher conference, leaving the mercury to be cleaned up by a janitor.
District officials were not aware of the incident until Oct. 26, and spent the weekend working with health officials, the Environmental Protection Agency, the Texas Commission on Environmental Quality and the North Texas Poison Control Center, the newspaper said.
"The mercury is not a health hazard to students or staff at the school as per health-based recommendations of the federal Agency for Toxic Substances and Disease Registry," the school statement said.
The school was open Monday.