Setting standards in the presence of developing scientific understanding.

The setting of standards for potential hazards as result of the application of a new technology depends on both the philosophy with respect to risk and the state of knowledge about the circumstances under which the technology can cause damage. Typically, biological damage is first observed for high levels of exposure and short times. As our understanding of the technology and its effects on the biology improve, biological effects are observed at lower levels and longer exposure times. For extended low-level exposures it also becomes more difficult to demonstrate a hazard that is independent of other influences. This has been true for electric and magnetic fields both at low and radio frequencies. In this article it is recognized that a set number is needed for both manufactures and system operators to meet if the technology is to serve the public. It is also recommended that the public be presented with tables of relative risks that include levels of exposure and other risks for comparison. Three tables of relative risks are included as a possible starting point.