Nearly half a million Illinois residents might be drinking water tainted with dangerous levels of radium, 25 years after the federal government set limits on the radioactive material.
Last week marked a deadline for water districts to finally meet those limits or explain how they plan to comply. But cleaning up the water comes at a price.
Removing the radium can cost anywhere from a few hundred thousand dollars to tens of millions. Although some districts have gotten grants or low-interest loans to help with the expense, customers in many towns are likely to face higher water rates.
Then there is the question of what to do with the radium after it is taken out of the water.
It is often dumped into sewer systems and sometimes ends up in sludge that is spread on farmland as fertilizer, a practice the U.S. Environmental Protection Agency questions.
''Human health risks due to radon inhalation are significantly greater in buildings constructed on lands that have been treated with fertilizers or sludges containing radium,'' according to a draft of proposed EPA guidelines for handling the material.
The radium is not pollution. It occurs naturally in some water supplies. In this state, the problem is largely in northern Illinois.
Over a person's lifetime, drinking water with high radium levels can increase the risk of cancer, particularly bone cancer. The risk at the EPA's maximum level is 1 in 10,000, but higher radium levels can raise the risks to 1 in 2,500 or even 1 in 1,000.
The original deadline for water supplies to meet federal radium limits was 1979, but the state has never enforced the limits. The Illinois Pollution Control Board regularly granted waivers that allowed water districts to operate without cutting radium.
In part, that was because the federal EPA at times suggested it would raise the radium limits. State officials were reluctant to require millions of dollars in water-treatment projects that might soon be unnecessary.
But in December 2000, the EPA decided to stick with the lower level of five picocuries -- that is, five-trillionths of a curie, a unit of radioactivity -- in every liter of water. Towns were given three years to comply.
Initially, the state EPA found that about 130 communities had excessive radium, with levels from just above five to 20 or more. Some towns began taking steps to comply, reducing the number of violators to 99. They served 449,000 people.
By Dec. 8, the deadline, two more water supplies had reported they were in compliance. Three others have installed radium-removal systems, 18 are building them and 61 have submitted proposals for compliance. Fifteen had not reported.
Towns can comply with the radium guidelines in several different ways -- digging new wells to tap clean water, overhauling old wells or connecting to another town's water supply.
They also can set up systems to remove the radium entirely, but that leaves them with a bunch of radium to dispose of.
Normally it is flushed into the sewer system with wastewater, where it can build up in pipes. Most of it goes to sewage treatment plants and winds up in waste lagoons. When those lagoons dry up, the remaining solid material is often used as fertilizer.
That means farmers and their neighbors can be exposed to it, and homes may be built on the land later.
Critics of the practice don't argue that it presents a clear danger, but say it raises health questions that people deserve to have answered.