Human subjects (n = 36) working at radio broadcast stations (n = 12 each at AM, TV, satellite) were assessed for serum melatonin and correlated with field density measurements at their respective work sites. The authors report highest RF levels at AM stations (avg 3.1 W/cm2, max 137 W/cm2), moderate levels at TV stations (avg 1.89 W/cm2, max 5.24 W/cm2), and lowest levels with satellite station operators (who were used as the control group). The authors report no effect of workplace RF level on melatonin (via aMT6s) levels, although there was increased cortisol (p<0.001), adrenaline (p=0.028) and noradrenaline (p<0.000) with thehighest level of exposure (AM radio stations. In a related study, physical therapy operators exposed to diathermy equipment (150 kHz, 27 MHz, 2450 MHz) were evaluated for arterial blood pressure and lipid profiles. The authors report significant increases with RF exposure for total cholesterol (both HDL and LDL) although blood pressure was not affected.