SEATTLE (AP) -- U.S. Environmental Protection Agency investigators prompted by a resident's concern in late 2012 tested rocks near a housing development in Burlington, Washington, and found evidence of naturally occurring asbestos.
Prolonged exposure to the substance found inside the rocks has been shown to cause lung cancer, and investigators recommended in a draft report that signs be posted to alert people to asbestos presence.
Residents, however, were never formally notified of the discovery by federal, state or local officials -- a case that experts say highlights the challenges authorities face when dealing with naturally occurring hazards.
Natural asbestos is often found in certain types of rocks and near fault zones. It can be released into the air from the rocks when they are broken or crushed, as occurs during mining or development.
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