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Fatal Hydrogen Sulfide Incident in a Shipboard Confined Space
In June 2022, two technicians entered a cargo tank on board a Danish tanker that had recently held soybean oil. The workers were overcome by hydrogen sulfide and later passed away. The source of the hydrogen sulfide was determined to be seawater that had been used to wash the tank three weeks earlier. As described in a report from the Journal of Occupational and Environmental Hygiene, seawater contains both sulfate and sulfate-reducing bacteria, or SRB. Sustained by the residue of soybean oil in the tank, SRB converted the sulfate to sulfide, producing dissolved hydrogen sulfide that was released as H2S gas. As this issue of The Synergist went to press, the JOEH report had not yet been assigned to an issue but was available online to AIHA members. Information from the report appears below.
From “Confined Space Hazards: Plain Seawater, an Insidious Source of Hydrogen Sulfide”:
“Foremost, the case highlights the importance of routine forced ventilation and extensive gas testing before entering empty cargo tanks even when no harmful gases are expected. Further, this study’s results can also provide useful insight for other industries, where entry into confined spaces which contain seawater takes place.”
SOURCE
Journal of Occupational and Environmental Hygiene: “Confined Space Hazards: Plain Seawater, an Insidious Source of Hydrogen Sulfide” (June 2023).
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