About 1995, something may have happened in the Fallon area that caused a spike in childhood leukemia cases, doctors say.

In an area that should average one case of acute lymphocytic leukemia every five years, Fallon, in a county of 26,000 people, has had one case of the disease diagnosed in 1997 and 11 more cases of the disease confirmed since 1999. ALL is the most common childhood cancer, but still fairly rare. Just 2,000 new cases are diagnosed annually in the United States.

Everyone is asking the same questions: Why Fallon? Why now?

“There are so many variables among the families who have children with leukemia and so many other variables that I think the chances of finding out where the illness came from are slim,” said Reto Gross, whose son, Dustin, 5, is among the patients in the cluster. Dustin, after two years of chemotherapy, is in remission from the disease.

“But do I want them to continue to search for the cause? Yes! I hope they don’t quit looking for what happened here, why it happened here,” Gross said.

The cluster is under investigation by state and federal officials.

State health officials last year gave questionnaires to the 12 families to determine what they had in common. Did they all shop at the same store? Did they send their kids to the same schools? Do they use a certain type of kitchen product or share the same habits or drink water from the same source?

The survey found only one common trait: the families of all the patients lived in Fallon for some period of time between 1995 and 1999.

“We haven’t found things that are strikingly in common,” said Dr. Randall Todd, state epidemiologist. “One of the things we are looking at is what has changed in the community since 1995.”

None of the children in the Fallon cluster has died. The federal Centers for Disease Control and Prevention in Atlanta and other health sources put the survival rate of ALL leukemia at 80 percent.

“Why Dustin and not our other three children?” Gross said. “Why the (12) children and not all the children? Was it something in the soil, water or air? Is it gone or is it still here?

“So many angles. So many questions.”

Wide speculation

Health officials and Fallon residents have speculated about a wide range of potential causes, including jet fuel, agricultural chemicals, atomic testing, industrial pollution, and the high levels of arsenic in area groundwater.

Todd said the answers may never be found. From 1961 to 1982, the CDC investigated 108 cancer clusters in 29 states and five foreign countries. In none of the cases did the CDC find a cause.

Here’s what is known so far about the Fallon cases:

o Arsenic: Some scientific studies on rats have suggested links between arsenic and leukemia. But the connection is discounted by experts who haven’t seen large increases in leukemia in other areas with high levels of arsenic in water supplies.

Todd said it’s unlikely the cancers were caused by Fallon’s long-standing arsenic problem, 10 times recommended federal standards. In addition, the 12 patients all drank from different water sources, according to the state’s survey of the families.

o Virus theory: The state’s panel of experts convened to look into the leukemia cluster raised the possibility of a virus cause but said more study is needed.

The experts panel, formed by state Health Officer Mary Guinan, said the infectious agent theory is based on “population mixing” — an “unusual mixing of people, often in relatively isolated rural areas.”

In such cases, exposure to infection could “trigger an unusual and rare reaction that affects a very small number of children,” the panel’s report states.

Guinan said the complex theory assumes chromosome damage resulting from infection, and the chromosome damage in turn could lead to cell abnormalities such as ALL.

The experts said that to test the hypothesis, rates of ALL should be calculated in other rural areas which have a lot of “population mixing” and getting more information on population movements in the Fallon area from 1990 to 2000.

o Random occurrence: Epidemiologists say cancer clusters may just be random — like flipping a coin and having it land on heads 12 times in a row.

o Atomic testing: Although Fallon is only 28 miles from the site of a 1963 nuclear bomb test, Department of Energy officials said last week radiation hasn’t migrated to the town.

“There’s no evidence that radioactivity has moved off the site,” said Nancy Harkness, DOE spokeswoman in Las Vegas.

She said there’s movement of water deep below the site in the Sand Mountain Range 28 miles southeast of Fallon, but the movement is easterly — away from the town and toward a navy bombing range.

In 1963, the Shoal Nuclear Test Site 28 miles from Fallon was ground zero for a 13 kiloton atomic bomb. That device is three kilotons weaker than the bomb that leveled the Japanese city of Hiroshima at the end of World War II.

The Cold War test was done underground, where it left a large underground cavity, vaporized rock and disbursed radioactivity below the surface.

Government scientists use eight on-site wells and a dozen off-site wells to search for radionuclides like tritium, a culprit in some of the cancer clusters found near nuclear processing plants in Britain.

“The highest reading we ever got was in 1996 at an on-site well very close to ground zero,” Harkness said. “That well showed a reading of 1,000 picocuries of tritium per liter. The standard for tritium in water is 20,000 picocuries per liter.’

DOE project manager Pete Sanders said any surface contamination is long gone. He said the ground water below the site doesn’t connect with the Basalt Aquifer, the source of Fallon’s drinking water.

“The water is pretty much localized,” he said. “So is the radiation. As far as we know, it hasn’t migrated out of that area.”

o Pesticides and other toxic chemicals: The state’s expert panel said leukemias in Fallon are not commonly associated with toxic chemical exposure.

Recommendations from the panel include more study, the collection of biologic specimens and an effort to pinpoint any “excess environmental exposures.”

o Industrial pollution: The state panel recommended looking at any toxic emissions from plants in that area.

LEUKEMIA HOTLINE

o State Health Division officials have set up a Community Hotline, open weekdays between 8 a.m. and 6 p.m., for inquiries about the leukemia cluster in Fallon: (888) 608-4623.