Chapter 97 - Two Unusual Situations of Excess Iodine Ingestion: A Faulty Iodinator and the US Space Program

Abstract

American Peace Corps volunteers in Niger, West Africa must drink iodine-treated water to avoid microbial contamination commonly found in many areas of rural Africa. It was noted that between 1995 and 1998, many of these volunteers developed goiters. It was subsequently found that the two-stage iodine-resin ceramic filters used to iodize the water was faulty and was delivering approximately 10 mg iodine/l of water. Since Niger is arid and hot, these volunteers were drinking 5–9 L of water daily, resulting in the consumption of 50–90 mg iodine daily, far above the US RDA of approximately 150 g iodine daily. The median urine iodine excretion was an astonishing 5048 μg/l. Following the discovery of the faulty iodinator, the volunteers were re-evaluated at a mean of 30 weeks later. Although iodine has been used in the US Space Program as an antimicrobial to disinfect the potable drinking water system during space flight, it was not considered to have an adverse effect on thyroid function until the late 1990s. Iodine concentrations in the drinking water reached concentrations as high as 36 mg/l; in the Shuttle Program (1981–present), iodine was added by an iodinated anion-exchange resin resulting in a concentration of approximately 4 mg/l in the drinking water. American astronauts are no longer exposed to excess iodine ingestion from iodized water since the iodine is removed by activated charcoal and an ion-exchange resin just prior to drinking.