Navys Recommended SEALs

TABLE S-l Comparison of the Navy s Proposed SEALs with the Subcommittee s Recommended SEALs... 

Navy s (ppm)a Proposed SEALs Subcommittee s Recommended SEALs (ppm)b ... 

On the basis of its review of human and experimental animal health-effects and related data, the subcommittee concludes that the Navy s proposed SEAL 2 of 85 ppm for carbon monoxide is too conservative. The subcommittee recommends a SEAL 2 of 150 ppm, which would not result in blood COHb concentration above 20%. Human data suggest that at a COHb concentration of approximately 20%, some submariners could experience mild headache and some decrement in cognitive function (Schulte 1963 Parving 1972 Stewart et al. 1973). Such effects would not impair the ability of a crew to escape from a disabled submarine. The recommended SEAL 2 is also supported by Theodore et al. (1971) where monkeys were exposed to a carbon monoxide concentration of 380 ppm for 90 d (COHb=31%) and there were no adverse health effects. 

This chapter reviews physical and chemical properties and toxicokinetic, toxicologic, and epidemiologic data on carbon monoxide. The Subcommittee on Submarine Escape Action Levels used this information to assess the health risk to Navy personnel aboard a disabled submarine from exposure to carbon monoxide and to evaluate the Navy s proposed submarine escape action levels (SEALs), proposed to avert serious health effects and substantial degradation in crew performance from short-term exposures (up to 10 d). The subcommittee also identifies data gaps and recommends research relevant for determining the health risk attributable to carbon monoxide exposure. 

The Navy proposes to set a SEAL 1 of 1 ppm and a SEAL 2 of 4.5 ppm for exposure to hydrogen cyanide. The Navy based the SEALs on NIOSH (1994) recommended daily limit of 4.7 ppm and on the American Conference of Governmental Industrial Hygienists Threshold Limit Value (TLV) (ACGIH 1998) of 4.5 ppm. 

---