Consensus Report

Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants (2007)

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Navy personnel who work on submarines are in an enclosed and isolated environment for days or weeks at a time when at sea. Unlike a typical work environment, they are potentially exposed to air contaminants 24 hours a day. To protect workers from potential adverse health effects due to those conditions, the U.S. Navy has established exposure guidance levels for a number of contaminants. The Navy asked a subcommittee of the National Research Council (NRC) to review, and develop when necessary, exposure guidance levels for 10 contaminants. Overall, the subcommittee found the values proposed by the Navy to be suitable for protecting human health. For a few chemicals, the committee proposed levels that were lower than those proposed by the Navy. In conducting its evaluation, the subcommittee found that there is little exposure data available on the submarine environment and echoed a previous recommendation from an earlier NRC report to conduct monitoring that would provide a complete analysis of submarine air and data on exposure of personnel to contaminants.

Key Messages

  • A few onboard sources, such as cigarette smoking and certain cooking methods, contribute to the formation of multiple compounds considered in this report. Therefore, stricter management or elimination of those sources is likely to solve some exposure problems on board submarines.
  • Nitrogen dioxide must be monitored along with nitric oxide, because nitric oxide can combine with oxygen to form nitrogen dioxide, which is more toxic than nitric oxide.
  • Research is needed to quantify the diverse methods and end points used in sensory irritation studies, so that these data can be used in public- and occupational-health risk assessment with greater confidence.
  • The potential for antagonistic, additive, or synergistic interactions between contaminants in the submarine environment is an area of significant uncertainty that remains largely unexamined and needs to be studied.
  • The subcommittee derived guidance levels for both nitric oxide and nitrogen dioxide, whereas the Navy proposed values for only nitrogen dioxide, assuming that those guidance levels would also be protective in the event of nitric oxide exposure.
  • The subcommittee found substantial differences in the adequacy of the data sets used to derive the EEGLs and CEGLs. For example, formaldehyde has a robust data set that includes both occupational and controlled human studies, whereas monoethanolamine has a paucity of data available for determining effects following inhalation exposure.
  • The submarine atmosphere does not appear to be well characterized. In conducting its evaluation, the subcommittee found that few exposure data are available on the Navy�s chemicals of concern or other chemicals.