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Report - Technical

Subject: 	Ship Boat POSEIDON  incident:  Possible Chemical Hazards

        As requested by CAPT Kichner, CO MSO Mobile, AL, all possible chemistry hazards
related to the F/V POSEIDEN and the death of it's three crew were investigated.  An
assessment of potential chemical hazards and scenarios which could have caused or
contributed to the death of the crew are postulated in this preliminary report.  Since air
sampling and forensic results such as blood chemistry have not been finalized or reported,
none of the following possible scenarios have yet been eliminated.  The purpose of this
report is merely to present possible scenarios which could have resulted from chemical-
reactions aboard the vessel.


        Scenario 1:  Asphyxiation by Engine Exhaust.  A crack in the bulkhead was observed
as was exhaust gases entering the hold while the generator was running.  The main diesel
engine had been running, but had stopped some time after the death of the crew.  An
exhaust leak is suspected but has not yet been confirmed by investigation.  Engine exhaust
entering the hold may have caused asphyxiation of the crew members.  Carbon monoxide (CO)
and various other fuel exhaust fumes such as NO2 and SO2 can cause death (IDLH for CO,
NO2, and SO2 are 1200, 20, and 100 ppm, respectively).  Blood chemistry results may
provide forensic evidence of CO asphyxiation.  Additional air sampling, with both engine
and generator running, would provide additional information to evaluate the possibility of
this scenario.


        Scenario 2:  Misuse of Chemical Preservative.  A chemical preservative, sodium
meta-bisulfite (Na2S2O5), was being used on the vessel.  While commonly used, it is a
potential hazard.  Material Safety Data Sheets (MSDS) for this chemical state that water
and ice yield sulfur dioxide (SO2), a highly toxic gas.  The chemical should be used in a
well ventilated space, otherwise, SO2, a heavier than air gas,  may accumulate in low
spots, such as the bottom of a hold.   A more rapid evolution of SO2 can result when
sodium meta-bisulfite is in contact with an strong oxidizing agent such as chorine bleach
(a chemical also found on the vessel).  The sodium meta-bisulfite was in the hold with the
victims.  Misuse of the preservative may have resulted in an unsafe working environment.
SO2 has an IDLH of 100 ppm.


        Scenario 3:  Formation of H2S in the Hold.  Decomposing shrimp and organic
material can produce hydrogen sulfide, H2S, a highly deadly poison.  H2S has an IDLH of
100 ppm.  H2S is easily detected at low concentrations (sub ppm levels), but at higher
concentrations (levels which are toxic) it quickly fatigues the sense of smell and is
undetected.  For H2S formation to occur, the following conditions must be present:  1) a
temperature high enough for bacteria to grow,  2) the absence of oxygen (at least within
the shrimp, fish, and slime), and 3) a source of sulfur (many protein amino acid groups
contain sulfur).  Again, because of the asphyxiation threat in a confined or semi-confined
space and the lack of sensory detection at toxic concentrations, H2S is a dangerous threat
and a potential contributor to this event.


        Scenario 4:  Oxygen Displacement.  The hold being a semi-confined space, the
exclusion of oxygen could reduce a crewmen's ability to escape and contribute to such an
incident. Asphyxiation is defined as a process by which a gas that has little or no
positive toxic effect, but which can bring about unconsciousness or death by replacing air
and thus depriving the organism of oxygen. Oxygen depravation begins when oxygen
concentrations are reduced to lower than 19.5%.  Significant reduction in human body
function occurs at concentrations approaching 16%.  Oxygen displacement is another form of
asphyxiation and can be caused by any of the above scenarios as well as the use of dry ice
as a refrigerant (no evidence of dry ice use is known).  In this incident, oxygen
displacement alone probably didn't cause death, but oxygen displacement maybe a co-
contributor.