Manufactured vitreous fibers (MVF), also known as synthetic vitreous fibers, are considered to be less hazardous than asbestos to human health. They are used in many thermal- and acoustical-insulation applications as an asbestos substitute or as a filtration medium. The Navy uses MVF in shipboard and onshore applications. To protect Navy personnel from harmful exposures to MVF, the U.S. Navy Environmental Health Center (NEHC) developed occupational exposure standards. The documentation assists industrial hygienists, occupational medicine physicians, and other Navy health professionals in assessing and controlling the health hazards linked with exposure to MVF. In 1997, the National Research Council (NRC) was asked to conduct an independent review of the Navy's toxicological assessment of MVF and to evaluate the scientific validity of its exposure standard of 2 fibers per cubic centimeter of air (f/cm3). The NRC assigned the task to the Committee on Toxicology, which established the Subcommittee on Manufactured Vitreous Fibers, a multidisciplinary group of experts, to determine whether all relevant toxicological and epidemiological data were correctly considered in developing the exposure standard; and to examine the uncertainty, variability, and quality of data and the appropriateness of assumptions used in the derivation of the exposure standard. The subcommittee was also asked to identify deficiencies in the MVF database and, where appropriate, to make recommendations for future research and data development. Review of the U.S. Navy's exposure Standard for Manufactured Vitreous Fibers represents the subcommittee's final report. The committee had expanded its review when in January 1999, the Navy revised its Occupational Safety and Health Program Manual (CNO 1999), changing the occupational exposure limit for MVF to the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 1 f/cm3. The report features recommendations by the subcommittee as well as information gaps found throughout investigation. Overall, the subcommittee found that the Navy made a good start in assessing the health effects of MVF, but needed further research.

Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 15 identifies, reviews, and interprets relevant toxicologic and other scientific data for ethyl mercaptan, methyl mercaptan, phenyl mercaptan, tert-octyl mercaptan, lewisite, methyl isothiocyanate, and selected monoisocyanates in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three level--AEGL-1, AEGL-2, and AEGL-3--are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

At the request of the Department of Defense and the Environmental Protection Agency, the National Research Council has reviewed the relevant scientific literature compiled by an expert panel and established Acute Exposure Guideline Levels (AEGLs) for several chemicals. AEGLs represent exposure levels below which adverse health effects are not likely to occur and are useful in responding to emergencies, such as accidental or intentional chemical releases in community, workplace, transportation, and military settings, and for the remediation of contaminated sites. Three AEGLs are approved for each chemical, representing exposure levels that result in: 1) notable but reversible discomfort; 2) long-lasting health effects; and 3) life-threatening health impacts. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 13 includes AEGLs for boron trifluoride, bromoacetone, chloroacetone, hexafluoroacetone, perchloryl fluoride, piperidine, propargyl alcohol, trimethoxysilane and tetramethoxysilane, and trimethylbenzenes.

"This publication represents the views and expert opinions of an IARC working group on the evaluation of carcinogenic risks to humans, which met in Lyon, 9-16 October 2001."

Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 20 reviews and updates the technical support document on acute exposure guideline levels (AEGLs) for selected chloroformates. This update focuses on establishing AEGL-3 values for n-propyl chloroformate and isopropyl chloroformate, but will also consider whether any new data are available that would affect the proposed values for the other 10 chloroformates. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

U.S. Navy personnel who work on submarines are in an enclosed and isolated environment for days or weeks at a time when at sea. 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. In this latest report in a series, the Navy asked the National Research Council (NRC) to review, and develop when necessary, exposure guidance levels for 11 contaminants. The report recommends exposure levels for hydrogen that are lower than current Navy guidelines. For all other contaminants (except for two for which there are insufficient data), recommended levels are similar to or slightly higher than those proposed by the Navy. The report finds that, overall, there is very little exposure data available on the submarine environment and echoes recommendations from earlier NRC reports to expand exposure monitoring in submarines.