BIOLOGICAL EFFECTS OF WEAK BLAST WAVES AND SAFETY LIMITS FOR INTERNALORGAN INJURY IN THE HUMAN-BODY

One hundred and seventeen adult sheep of both sexes, each weighing 15. 2-42.4 kg, were used for this study, The purpose of this study was to investigate the relationship of the physical parameters of the waves t o internal organ injury by exposing sheep to weak blast waves in TNT ( trinitrotoluene) explosions, biological shock tube, and gun muzzle bla sts, The results showed that the organ most sensitive to the TNT explo sion was the lungs, whereas the upper respiratory tract was most sensi tive to muzzle blast waves, The injury thresholds of overpressure were 29.0, 29.5, and 41.2 kPa for upper respiratory tract, lungs, and gast rointestinal tract respectively at a single exposure, Repeated exposur e to 60 blasts reduced the injury threshold of the internal organs, Th e injury thresholds for upper respiratory tract, lungs, and gastrointe stinal tract were 21.0, 18.0, and 40.4 kPa, respectively, The duration of overpressure of weak blast waves was 2.4-4.2 milliseconds, which d id not significantly affect the severity of injury, The safety limits of weak blast waves to internal organ injury of human body were as fol lows: Ps 37-3Ln . Tc . N/4(Tc . N less than or equal to 1000) and Ps = 20.4(Tc . N > 1000), The results suggest that repeated exposures decr ease the injury threshold of the internal organs, The safety limits pr oposed could protect 90% of the exposed population against internal or gan injury caused by weak blast waves.