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The primary objective of establishing SEALs is to protect crew members from adverse health effects—particularly to the respiratory and central nervous systems—from exposures to the combustion gases and chlorine. The Navy will use SEALs as one of many parameters in its Submarine Escape and Rescue Expert System model. That model takes into account several additional parameters, such as geographical position and depth of the submarine, number and medical condition of the crew members, ability to communicate with search and rescue forces, and compartment temperature, and is used by the senior officer to assist in making a decision on whether to escape from the disabled submarine.


Seeking to protect the safety of submariners, the chief of the Bureau of Medicine and Surgery requested that the National Research Council (NRC review the available toxicologic and epidemiologic data on eight gases that are likely to be produced in a disabled submarine and to evaluate independently the scientific validity of the Navy’s proposed SEALs for those gases. The NRC assigned this project to the Committee on Toxicology (COT) and assembled the Subcommittee on Submarine Escape Action Levels, which prepared this report. The specific task of the subcommittee was to review the toxicologic, epidemiologic, and related data on ammonia, carbon monoxide, chlorine, hydrogen chloride, hydrogen cyanide, hydrogen sulfide, nitrogen dioxide, and sulfur dioxide to determine the scientific validity of the Navy’s proposed SEALs. The subcommittee was also asked to consider the implications of exposures at hyperbaric conditions and potential interactions between the eight gases, identify deficiencies in the database relevant to setting SEALs for the eight gases, and recommend further research.


The subcommittee evaluated human data from experimental, occupational, and epidemiologic studies; data from accident reports; and experimental-animal data (single and repeated exposures). The evaluations focused primarily on high-concentration inhalation exposure studies. The subcommittee’s recommended SEALs are based solely on scientific data relevant to health effects.

In general, the subcommittee’s approach was to recommend SEALs based on human data to avoid the need for incorporating an interspecies uncertainty factor commonly used in the derivation of exposure guidance levels from animal data. In its derivation of SEALs, the subcommittee did not incorporate an

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