Hazardous material clean-up crews went through a Worcester elementary school Thursday removing any traces of mercury.
A 6th grader brought a vile of the chemical to school Tuesday.
Public health and environmental crews went through the Grafton Street Elementary School as well as the clothing and backpacks of the children wore on Tuesday and Wednesday.
Worcester Suptintendent Dr. Melinda Boone says only a few students and a teacher had contaact with the mercury that a boy says he found near his home.
Students attended classes at another location while the clean-up was underway.
Police are investigating where the mercury came from.