Eight days after elemental mercury was removed from an unlocked classroom at Ballou High School, environmental technicians on Friday were still testing and decontaminating the school and several homes tainted with the potentially toxic substance.
No one has shown any physical symptoms, said Dr. Michael S.A. Richardson, chief medical officer of the D.C. Health Department.
Of 48 homes checked, seven have shown indications of potentially unsafe mercury vapors. They will undergo the same type of decontamination as the school. Although some families have opted to remain in their homes, 28 people have moved into hotels at city expense.
``The mayor is considering declaring a public health emergency,'' said Tony Bullock, a spokesman for Mayor Anthony A. Williams.
At the school, mercury was spattered across walls, poured down drains, and thrown on people, winding up in the hair of some students. A student who admitted removing the mercury from the unlocked classroom sold some of it to another student for a dollar. That second student took it by bus to a 17-unit apartment building, which was later evacuated.
