In the preceding chapters I analyzed environmental issues in three different settings: the city, the wildlands, and the countryside. Another perspective of much greater scope exercised an equally formative influence in environmental affairs – an experience of a world of radiation and chemicals that pervaded almost every facet of human life. It reflected a concern about human health rather than about amenities and the permanence of natural ecosystems. This toxic “sea around us” became a preoccupation of many Americans. The air, water, and land were media through which threats affected a wide range of human experience.

This world was largely shaped by new developments in science and technology. Since the mid-nineteenth century, modern industry had brought together many of the earth's minerals such as lead, cadmium, asbestos, and beryllium from widely dispersed natural sources, concentrating them into both usable products and harmful by-products and wastes. Atomic fission and the use of X rays exposed humans to radiation considerably higher than background levels. Modern science generated new chemicals, the synthetic organics, not before known in nature. They were created precisely because they differed markedly from natural products, could withstand biological decay, and were more resilient.

The new chemical environment appeared to be both beneficial and harmful. The benefits were conveyed by innumerable products useful in daily life; the potential harm was made apparent by incidents in which human health and the functioning of biological life were impaired.