This report results from a contract tasking Russian Academy of Sciences as follows: Because of the widespread increase in man-made sources of electromagnetic fields (EMFs), including high peak-power pulsed EMF (HPPP EMF), it has become important to study the health consequences, including possible genotoxic effects of such fields. Because of the simultaneous increase in other environmental toxins, it is difficult to isolate the effects of EMFs in natural human populations. Therefore, this question must be studied under controlled laboratory conditions. The objective of the proposed project is the detection of possible HPPP EMF effects on biological systems at the subcellular and molecular levels. The primary effort will be to assess the effects of HPPP EMF on the genetic material and on intracellular biochemical processes that regulate DNA replication. In doing so, the researchers will develop and modify special methods for the analysis of nucleoid DNA structure on the basis of the single cell gel electrophoresis (comet) assay. Improvements in this method will raise its sensitivity reliability, and rapidity, as well as decrease its cost. The researchers plan to computerize the method using digital imaging and image analysis techniques. Results will help determine the basic biological effects of HPPP EMF and help provide a broader basis for setting appropriate safety standards.