Fatal inhalation of volcanic gases in three tourists of a geothermal area.

The study reports the environmental, toxicological and histopathological forensic investigations applied on three victims of accidental death (father, mother and son), due to the fall in a volcanic pothole, during the touristic visit of the "Solfatara park", near Naples (Italy). At autopsy greenish skin discolouration was observed and all bodies showed the classical signs of asphyxial deaths, such as cyanosis and hemorrhagic pulmonary edema. Focal micro-hemorrhages were found in the brain at intracranial and subpial levels. The hemogasanalysis and spectrophotometric test on blood for Methemoglobin (MetHb), Carboxyhemoglobin (HbCO) and Sulfhemoglobin (SHb) showed pCO, SHb and MetHb above the physiological levels. On biological specimens, toxicological analyses performed by GC/MS revealed high concentrations of hydrogen sulfide (HS) and of thiosulfate (TS), its main metabolite. The monitoring of toxic gases on the death scene showed an unsafe environment, into the pothole, able to cause the sudden loss of consciousness of the victims with subsequent asphyxiation (knockdown effect). In particular, at the bottom of the hole, the maximum levels of HS and carbon dioxide (CO) were 2200 ppm and 98% respectively. For the family members, the cause of the death was assessed as acute poisoning by HS and CO. The fatalities, happened in quick succession as for a domino effect, were pretty similar to the asphyxial deaths by confined spaces, frequently observed in occupational setting. Fatalities secondary to accidental volcanic gases inhalation, such as HS and CO in geothermal areas, have been already described but often without a forensic approach. To the best of our knowledge this is the first case that reports the accidental poisoning by volcanic gases involving three people, with different caracteristic of age and sex, allowing the correlation between toxicological and pathological results with the true levels of asphyxiating gas, measured on the death scene.