The objective of this study is to determine and dose-response relationships for effects of 27 MHS MHz and 2450 MHz radiofrequency (RF) radiation on mammalian somatic and germ cells in vitro under accurately measured and precisely controlled exposure conditions. Data resulting from this study will be used to assess health risks of occupational exposure to 27 MHz and 2450 MHz radiation generated by heat sealers, diathermy equipment, radio and television broadcast, and other sources. Current studies provide direct evidence that these frequencies of electromagnetic radiation alter cell functions including: mitogenesis, proliferation, energy metabolism, and in vitro fertilization, under exposure conditions that exclude thermal involvement. The significance of these findings resides in the fact that the electromagnetic fields per sect of these and most likely other RF radiation frequencies, interact directly with living systems rather than indirectly via heating. Consequently, exposure of humans to low intensity, or of more significance from an occupational exposure perspective, pulse or amplitude modulated RF fields, could involve alterations in cell function. Obviously it is not possible to directly extrapolate in vitro cellular data to in vivo exposure effects but the types of cell alterations suggest possible relationships to carcinogenesis, growth alterations and fertility. Well-characterized mammalian somatic cells including human erythrocytes and lymphocytes, fibroblasts, HeLa and glioma, and germ cells (mouse ova and sperm) will be exposed under conditions of accurately measured electric and magnetic fields strength in temperature controlled RF or microwave exposure chambers under isothermal conditions. Studies now in progress will provide dose thresholds for cellular alterations resulting from exposure to continuous wave (CW) 27- and 2450 MHz RF radiation. The proposed study will involve determination of thresholds for cells exposed to pulse-modulated (PH) 27 MHz or 2450 MHz fields at pulse repetition rates in the range of 0.1 to 60 Hz and maximum field strength of lkv/m. The dependent variables will be: a) plasmalemma cation permeability, b) DNA, RNA and protein synthesis, c) cell-cycle regulation, d) energy metabolism, e) sperm viability and motility, and f) fertilization (in vitro), g) receptor binding, h) second messenger activation, i) mitogenesis. In addition to comparing CW versus PM RF thresholds we will investigate the rate of post exposure cell recovery to shed light on the cumulation of RF-induced cellular alterations.