Experimental Measures of Blast and Acoustic Trauma in Marine Mammals

Blast traumas are essentially mechanical responses, therefore blast effects are inducible and
measurable in post-mortem specimens. To determine onset of damage zones for blast trauma in
marine mammals, fresh post-mortem specimens were implanted with pressure gages, CT scanned, and
exposed to underwater blast pressures of 10-300 psi. Following exposures, specimens were rescanned
and necropsied by a team of blast pathology specialists blinded to test pressures. All procedures were
documented by UW video and still photography. The results show severity and type of impacts are
mass-dependent and correlated with received psi. Classic blast damage was found in all tissues. Some
organs unique to cetaceans have distinct damage patterns that may be diagnostic in UW blast cases.
For the smallest species, safe margins are in the 10-12 psi received pressure range; for larger species
the ranges can be 20-25 psi. Important issues remaining to be tested include near field vs. far field
loading effects, exponential vs sinusoidal bursts, and synergistic effects of rate of pressure increase,
peak pressure, waveform and duration.