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Risks of Americium Fires

Americium is a man-made radioactive metal used for research and found in medical diagnostic devices, fluid-density gauges, thickness gauges, aircraft fuel gauges and distance-sensing devices. It is also found in a common type of household smoke detector, an ionization chamber detector.

  1. Ionization Chamber Detectors

    • Ionization chamber detectors work by ionizing radiation to develop a low, steady electrical current. If smoke particles enter the chamber, they disrupt this current. This disruption triggers the detector's alarm. Compared to photoelectric detectors, ionization chamber detectors more quickly detect fast-flaming fires that produce little smoke.

    Radiation Exposure

    • The radiation in ionization chamber detectors is contained in a small disc that weighs about 0.5 g. The disc is an americium-241 composite held in a gold matrix. According to the U.S. Environmental Protection Agency (EPA), an average smoke detector provides about 1 microcurie of radioactivity. Consequently, the EPA advises that the radiation exposure is negligible as long as the radioactive material stays contained in the detector. Therefore; these detectors should be properly disposed by returning them to the manufacturer when they become outdated.

    Characteristics of Americium

    • Americium is a man-made radioactive metal. It has a half-life of about 432 years, during which it emits low energy gamma rays and alpha particles. Compared to other radioactive elements, americium decays very slowly and emits very little radiation. Since a smoke detector has a useful life of 10 years, the Americium does not emit much of its radiation during this period.

    Burning Americium

    • The Nuclear Regulatory Commission permits the disposal of Americium-containing smoke detectors as ordinary trash. However, the EPA advises against burning these smoke detectors since this may cause additional exposure to Americium radiation. Americium radiation can be absorbed into the body through food, water, and inhaled air.

    Effect of Americium on the Body

    • Americium tends to concentrate in bone, liver and muscle, though it may also settle in the lungs when inhaled. Since it may stay in the body for decades, it continues to expose the surrounding tissues to its radiation. This may increase the person's risk of developing cancer. Even if the Americium is not ingested, significant amounts may still cause damage to bodily organs from direct external exposure.

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