<p>FOR the lawyers who file lawsuits against corporations, it looked like the next big thing — the next fen-phen, asbestos or even tobacco, the mother of all jackpots.</p>
<p>Like the lawsuits involving asbestos, the fire-retardant material that when inhaled can cause a horrible lung cancer, the new suits involved a substance that under certain circumstances could harm the lungs: silica, a purified sand used as a cleaning abrasive as well as in making glass, paint, ceramics and other materials. Silica dust, when inhaled, can lodge in the lungs, causing silicosis, a disabling and often fatal lung disease.</p>