What are the environmental and health effects of seeding material?
Minimal. The most common seeding material, silver iodide, is used in very minute amounts. The typical concentration of silver in rainwater or snow from a seeded cloud is less than 0.1 microgram per liter (one part in 10,000,000,000). This is well below the acceptable concentration of 50 micrograms per liter, set by the U. S. Public Health Service. Many regions have much higher concentrations of silver in the soil than are found in precipitation from seeded clouds. The concentration of iodine in iodized salt used on food is far above the concentration found in precipitation from a seeded storm. National Environmental Policy Act compliance for all cloud seeding environmental impacts has been demonstrated by past studies. The U.S.
