Potential health implications associated with particulate matter exposure in deployed settings in southwest Asia.

There is a recognized need to identify the potential impact of air pollution exposure on the health of military personnel deployed to Southwest Asia (SWA). The exposure characterization reported by Engelbrecht et al. in this issue summarizes the results of a remarkable effort to conduct environmental sampling at locations where US military personnel are deployed in support of Operation Enduring Freedom and Operation Iraqi Freedom. This is an important first step in better understanding the relationship between the health of soldiers deployed in SWA and air pollution in the area of operations. We discuss here what is currently known about the effects of particulate matter (PM) on human health, focusing on the limited evidence specific to US military personnel, and outline current and planned efforts to utilize sampling data to assess health outcomes in deployed military populations.

Intraindividual stability of human erythrocyte cholinesterase activity.

BACKGROUND: Erythrocyte cholinesterase (RBC-ChE) activities serve as useful and sensitive biomarkers to monitor exposure to cholinesterase-inhibiting substances, such as chemical warfare nerve agents and pesticides. Although the interindividual variation of RBC-ChE is well characterized, the magnitude of intraindividual variation for RBC-ChE remains controversial. An accurate measure of intraindividual variation is critical for establishing the appropriate frequency of RBC-ChE testing. METHODS: We retrospectively tracked the intraindividual variation of RBC-ChE activities among 46 male nerve agent workers from a single US Army depot that participated in a medical surveillance program requiring periodic RBC-ChE monitoring. All RBC-ChE analysis was performed by the same medical laboratory technician by the delta pH method. RESULTS: A mean of 38 and a median of 37 RBC-ChE measurements were available for each worker. The mean duration of employment for these workers was 20 years (median, 21 years). The mean CV for RBC-ChE in this set of 46 workers was 3.9%. Linear regression analysis of the data for each worker resulted in a mean slope of 0.0010 delta pH units/h per year. CONCLUSIONS: RBC-ChE activities increased in each person by a mean of 0.01 delta pH units/h every 10 years, which is a negligible rate. These findings highlight the stability of RBC-ChE activities over time in a given individual and may have important policy implications regarding the appropriate frequency of RBC-ChE testing.