Fallon is a nondescript little town in Nevada. Nondescript except for the Naval Air Station found there. And for one more thing. A cluster of acute lymphocytic leukemia. This is a disease in which too many underdeveloped viral infection-fighting white blood cells, called lymphocytes, are found in a child’s blood and bone marrow. A disease cluster is the occurrence of a greater than expected number of cases of a disease within a group of people, geographic area, or a period of time. True clusters are difficult to define and the causes are often obscure. Most non-occupational cancer clusters turn out to be the result of the random nature of the disease, but clusters of the type found in Fallon definitely merit investigation. From 1997 through 2001 leukemia was diagnosed in 16 children in the Fallon area. A population of 8000 or so as found in Fallon would be expected to have no more than 1 case every three years.
When epidemiologists begin to investigate such clusters, they ask the question, "what is different here?" The Naval Air Station immediately comes to mind. Airplanes sometimes jettison fuel; could this be the cause of the leukemia? Jet fuel is released, by regulation, only during emergencies, at very high altitudes. Because it is so high in the atmosphere, it aerosolizes, or breaks up into very fine particles that spread out quickly and evaporate. Very little fuel, if any, makes it to the ground. What about leaks from a pipeline that delivers the fuel to the base? None have been found. In any case, numerous health studies on the safety of jet fuel indicate there is no evidence to suggest a link between jet fuel and leukemia.
Next, the town's water supply was tested for pesticides, industrial chemicals and metals. Slightly elevated levels of uranium and arsenic were found but this was not deemed to be of any consequence. What was surprising though was the finding of tungsten at levels thirteen times greater than the national average. Tungsten is the metal used in light bulbs and is commonly alloyed with iron to increase the strength of steel. It has not been associated with health problems and is not a regulated pollutant. When trees in the are were investigated their outer rings also had a higher tungsten content, perhaps showing recent exposure. The source of the tungsten may be a smelting plant some twenty miles away. Can tungsten perhaps cause leukemia? One small study in the scientific literature has shown human bone cells turning cancerous in its presence and another one showed leukemia cells multiplying more quickly in a tungsten solution. So far nobody knows what all of this means but we may eventually have to add tungsten to the list of substances to worry about. Or the leukemia cluster in Fallon may just be a quirk of nature.