uted to the Army's zinc cadmium sulfide dispersion tests, because the exposures occurred more than 30 years ago, and the concentrations in most cases were below the background concentrations encountered in urban areas.
11. Is it possible to conduct an epidemiologic study of zinc cadmium sulfide-exposed persons?
Many people in the test areas have asked whether it is possible to look for health effects in people who might have been exposed during the tests. However, several problems make such studies unfeasible. The diseases reported by people at the public meetings occur often in human populations, and it is very difficult to pinpoint the exact cause of these diseases. After 30–40 years, it would be very hard to identify the people who were exposed or affected and to determine their past exposures to zinc cadmium sulfide. Even if the exposed people could be identified, even a large epidemiologic study would not be able to distinguish the health effects of zinc cadmium sulfide from those associated with other factors, such as breathing cadmium in typical urban air for a few weeks.
12. Were biologic materials used in the Army's testing program?
Review of the Army's files related to the zinc cadmium sulfide dispersion tests showed that in several cases tests were also conducted with microorganisms—such as Serratia marcescens, Bacillus globigii, or some species of Aspergillus (fungus or mold)—either alone or with zinc cadmium sulfide. All those organisms were considered by the Army to be safe at the time of their use. Relatively recent research has indicated that those microbes do not produce disease in healthy people, but some could cause disease in persons whose immune (body-defense) system is weak. Although some of the Army's tests involved exposures to zinc cadmium sulfide at the same time as microorganisms, such