Radium problems in Illinois In Illinois, high radium levels occur primarily in the northern third of the state due to the presence of radium in the granite bedrock that surround aquifers from which water supplies are drawn, according to the state Department of Public Health. All public water supply wells are tested regularly for radium, officials said, and while most shallow aquifers do not contain significant amounts of radium, the substance has been found in some private and non-community public wells. Radium cannot be seen, tasted, or smelled in drinking water, health officials said. Radium samples from public water supplies are taken quarterly, tested by the Illinois Department of Nuclear Safety, and averaged over a one-year period. What's the harm? Radium in water may pose a hazard to human health when the water is used for drinking, the health department said. No more than 20 percent of the ingested radium is absorbed from the digestive tract and distributed throughout the body. It behaves similarly to calcium and is deposited in the tissues of the body, especially bone. The radiation received externally through showering, washing, or other uses of radium-containing water is insignificant since the skin blocks the alpha radiation, officials said. But internally deposited radium emits radiation as alpha particles that may then damage tissues found within the surrounding few millimeters. The health department said it is not known to cause adverse health effects at levels generally encountered in drinking water, diet, or the environment. But studies of workers exposed to high levels of radium and other sources of alpha radiation for extended periods show that high levels of radium may cause depression of the immune system, anemia, cataracts, fractured teeth, and some types of cancer. — R.J.D.