ABSTRACT
Toxic waste is very difficult to recycle, and disposal requires careful handling and long-term monitoring. Roughly 35 million pounds of hazardous waste are disposed of in the United States each year. The preferred method of dealing with toxic substances is to reduce their use in agriculture, manufacturing, and household cleaning products. Toxicologists say that there are no hazardous substances until people are exposed to certain levels of concentration. Some toxic substances occur naturally, such as the heavy metals arsenic, cadmium, chromium, copper, lead, mercury, and zinc. Other toxic substances are man-made. In the early 1970s, Congress embarked on more than a decade of legislation to identify toxic substances and regulate their manufacture, transportation, use, and disposal. A very real concern about the new information economy is the use of toxic substances in manufacturing computers and related high-tech equipment. Since Silicon Valley arose as a major computer manufacturing region, 29 properties have been declared Superfund hazardous waste sites.
