Why? Because salt can react badly with, well, just about everything, says Steven Apfelbaum, founder of the environmental consulting firm Applied Ecological Services, Inc. and author of Restoring Ecological Health to Your Land. Salt has chemical properties that make it react with, and alter the composition of, iron, steel, zinc, concrete, wire insulation, and more--nearly all the building blocks of the manmade environment. It not only corrodes wires that can transmit electricity, it also conducts a charge itself, which means that it can both wear away our safety insulations, causing outages, and increase the chance of an accidental shock. When coated with salt, metal can transfer a jolt, too.