Living with radiation: human health and nuclear exposure.

Inside the "Chernobyl Zone"--an 18-mile circle around the nuclear complex that caught fire and exploded in April of 1986, spewing radiation across 150,000 square miles of European territory--there is an abandoned amusement park, complete with Ferris wheel, that never opened for business.

There were 60,000 people living in the villages and towns around Chernobyl and Pripyat in 1986, and the multi-story apartment blocks they lived in still stand in neat rows, their contents long since looted. These towers were evacuated the day after the explosion, the worst nuclear accident in human history.

Although the streets are mostly empty, new grass pokes through Chernobyl's broken pavement, and colorful graffiti enlivens some of the gray walls.

Despite radiation levels that set Geiger counters clicking, small but determined colonies of farm families remain in some of the villages surrounding the zone, even though they know the dangers and many of the children are sick. Thyroid cancers are so common that the scars left at the base of the neck after surgery are known as the "Chernobyl necklace."

Reports of Chernobyl casualties vary considerably, from 50 deaths reported by the World Health Organization to 212,000 cited by the Russian Academy of Medical Sciences. Many of Chernobyl's victims will come later, as birth defects, cancer, heart disease, kidney disease and scoliosis are reported among survivors.

Americans exposed to low-level radioactivity after the nuclear accident at Three Mile Island in Pennsylvania in 1979 have fared much better. A 1999 study of mortality in the Three Mile Island area found no deviation from normal death rates. (Another study, however, showed a statistically significant higher incidence of cancer and heart disease.)

The Nuclear Regulatory Commission (NRC) claims that the Three Mile Island accident, a near-meltdown caused by the loss of cooling water at the reactor core, "led to no deaths or injuries to plant workers or members of the nearby community," but given the slow incubation of some cancers, this statement may still be premature.

Several studies indicated that the average radiation dose to people living near the plant was one millirem, a sixth the dosage from a set of chest X-rays. But people living on the site boundary could have been exposed to as much as 100 millirems.

The Nuclear Energy Institute claims that radiation is relatively benign, with no cancer increases noted among people living in areas (in China, India and Brazil) that have natural background radiation several times higher than average. It also says that the radiation exposure for people living near operating nukes is "about the same as watching television."

But people fear exposure to radiation for a good reason. The effects of significant exposure range from radiation sickness (whose symptoms include vomiting, diarrhea, dehydration, hair loss and uncontrolled bleeding) to cancer (with a latency period that sometimes makes it hard to pinpoint the source of disease) and birth defects.

"All radiation is cumulative," writes Dr. Helen Caldicott in her book Nuclear Power is Not the Answer. "Each dose adds to the risk of developing cancer or mutating genes in the reproductive cells."

Despite industry campaigns, it's unlikely most people will ever be totally comfortable with nuclear plants as neighbors. An important 2004 study by the National Academy of Sciences concluded that "there is no compelling evidence to suggest a dose threshold below which the risk of tumor induction is zero." In other words, in terms of cancer risk, the only safe dose is no dose. CONTACTS: Nuclear Energy Institute, [phone], www.nei.org; Nuclear Policy Research Institute, [phone], www.nuclearpolicy.org.