Finding 3-1: The committee concurs with the non-stockpile program’s plans to replace the CDC 1988 WPLs with the 2003/2004 STELs for NRT monitoring.

Recommendation 3-1: PMNSCM should continue with its plans to replace the CDC 1988 WPLs with the 2003/2004 STELs for near-real-time monitoring.


The revised AELs do not reflect any change in agent toxicity. Workers, communities, and the environment were sufficiently protected under the old AELs. The revised AELs are, however, more stringent and more in line with how these standards are established for other air toxins. This standardization should help ensure the continued safety of workers, communities, and the environment since the revised AELs are more stringent and will result in a reexamination of all aspects of the protection of these populations and the environment.

The revised AELs, including the WPL, the GPL, and the IDLH, do not offer any clear quantitative risk advantage vis-à-vis the 1988 AELs. The 2003/2004 AELs are slightly more conservative than the 1988 AELs, but both are low enough that any quantitative comparison between the two is over-whelmed by the uncertainty in the current understanding of low dose effects. Further, the impacts of chronic exposures are difficult to assess owing to a lack of data.

This lack of demonstrable risk benefit is consistent with the position the CDC took when it announced the new AELs:

There is no indication that the current exposure limits, as implemented by U.S. Army PMCD, have been less than fully protective of human health. (Federal Register, 2002, p. 895)

The recommended changes in the AELs do not reflect change in, nor a refined understanding of, demonstrated human toxicity of these substances but rather the changes related from updated and minimally modified risk assessment assumptions. (Federal Register, 2003a, p. 58350)

The revision of the AELs has significant impacts on the operations at chemical agent demilitarization sites, training facilities, and laboratories. In accordance with U.S. Army guidance (2004b), the Army’s monitoring program must change such that an extra level of chronic monitoring at the WPL is introduced. Other areas are also affected, such as safety and emergency response procedures, medical monitoring programs, marking and handling of contaminated materials, release of contaminated materials, and handling, treatment, and storage of waste (U.S. Army, 2004b). It is possible that some improvements in worker risk and operations will result from implementing the revised AELs. These benefits will probably come from a fresh look at operating procedures rather than from the change in AEL values.

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