When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically. This idea, known as the "Precautionary Principle," is seen by environmentalists and public health experts as the way to protecting ecological and human health. In 1998, the Wingspread Conference on Implementing the Precautionary Principle was convened to discuss ways of incorporating the precautionary approach into environmental and public health decision-making. The workshop focused on understanding the contexts under which the principle developed, its basis, and how it could be implemented. Protecting Public Health and the Environment is an outgrowth of that conference.