A 56-year-old man died following a fall resulting in complete submersion into a deep pit containing insulation material, expanded perlite. The most striking finding at autopsy was of impacted, moist pale yellow perlite that extended from the epiglottis into the main bronchi resulting in complete obstruction of the larger and smaller airways with cast formation. Perlite inhalation differs from inhalation of inert materials such as sand and wheat due to its hygroscopic properties and ability to expand forming an occlusive cast. Subsequent analyses of perlite from the worksite and within the airways indicated that hydration of perlite and adsorption of organic molecules into the perlite glass flakes had formed an interlocking, three-dimensional structure that was likely responsible for triggering a coagulation-flocculation process causing strong cohesion between the aggregates of glass flakes. This unique mechanism was likely responsible for the formation of the plug of perlite that obstructed the upper airway.
Keywords: autopsy; cast formation; energy dispersive x-ray spectrometry; forensic pathology; hygroscopic; industrial accident; perlite; powder x-ray diffraction; scanning electron microscopy; upper airway occlusion.
© 2020 American Academy of Forensic Sciences.