Those abandoned mines are relics of the gold rush, and according to the Sierra Fund, those same mines are potential public health disasters. Many off roaders and horseback riders use the mine areas around Nevada City. Sierra Fund CEO Elizabeth Martin says tests show some of those trails are contaminated with asbestos, arsenic and lead.
"It's sort of like having your children ride their equipment or their horse through toxic air particles," says Martin. "[That] not only have lead and arsenic absorbing into their blood, but also actually shards or fibers of asbestos lodged into their lungs."
Asbestos can cause a form of lung cancer, while lead and arsenic are deadly at high levels. There have been no official health advisories, and so far there are no studies linking exposure in that area to an increase in detected lead or arsenic levels.
Martin is asking the U.S. Forest Service, which oversees many of these areas, to do further study the soil and post signs outlining the risks.