The chemical PCB (polychlorinated biphenyl) has been found in some schools. Although the chemical, which belongs to a category of manmade organic chemicals known as chlorinated hydrocarbons, was banned for use in 1979, it can still be found in some old buildings, including schools. PCB is especially dangerous to children because it is associated with learning problems and hormone disruption. It is also associated with a number of health effects, including cancer.
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