Academic journal article Environmental Health Perspectives

Probability Estimates for the Unique Childhood Leukemia Cluster in Fallon, Nevada, and Risks near Other U.S. Military Aviation Facilities

Academic journal article Environmental Health Perspectives

Probability Estimates for the Unique Childhood Leukemia Cluster in Fallon, Nevada, and Risks near Other U.S. Military Aviation Facilities

Article excerpt

A unique cluster of childhood leukemia has recently occurred around the city of Fallon in Churchill County, Nevada. From 1999 to 2001, 11 cases were diagnosed in this county of 23,982 people. Exposures related to a nearby naval air station such as jet fuel or an infectious agent carried by naval aviators have been hypothesized as potential causes. The possibility that the cluster could be attributed to chance was also considered. We used data from the Surveillance, Epidemiology, and End Results Program (SEER) to examine the likelihood that chance could explain this cluster. We also used SEER and California Cancer Registry data to evaluate rates of childhood leukemia in other U.S. counties with military aviation facilities. The age-standardized rate ratio (RR) in Churchill County was 12.0 [95% confidence interval (CI), 6.0-21.4; p = 4.3 x [10.sup.-9]]. A cluster of this magnitude would be expected to occur in the United States by chance about once every 22,000 years. The age-standardized RR for the five cases diagnosed after the cluster was first reported was 11.2 (95% CI, 3.6-26.3). In contrast, the incidence rate was not increased in all other U.S. counties with military aviation bases (RR = 1.04; 95% CI, 0.97-1.12) or in the subset of rural counties with military aviation bases (RR = 0.72; 95% CI, 0.48-1.08). These findings suggest that the Churchill County cluster was unlikely due to chance, but no general increase in childhood leukemia was found in other U.S. counties with military aviation bases. Key words: ALL, childhood cancer, cluster, leukemia, military. Environ Health Perspect 112:766-771 (2004). doi:10.1289/ehp.6592 available via http://dx.doi.org/[Online 2 February 2004]

**********

Leukemia is the most common cancer diagnosed in children < 19 years of age (Ries et al. 2003). Several factors have been associated with increased rates of childhood leukemia, including ionizing radiation, Down syndrome, and certain inherited and congenital conditions (Little 1999). However, known causes explain only a small fraction of all cases of leukemia.

This article was prompted by a recent cluster of leukemia cases occurring near the naval air station in Fallon (NAS Fallon), Churchill County, a sparsely populated area in western Nevada. From 1999 to 2001, 11 cases of childhood leukemia were diagnosed among children residing in Churchill County at the time of diagnosis. An additional five cases have been identified from 1997 to 2002 among children who were nor residents at the time of diagnosis but who lived in Churchill County at some point before diagnosis [Nevada State Health Division (NSHD) 2003]. In the preceding 20 years, only one case of childhood leukemia was reported to the Nevada Central Cancer Registry among Churchill County residents (Moore et al. 2002). This dramatic increase in the number of cases, the short time frame in which the cases were diagnosed, and the small population of the source area all highlight the unusual nature of this cancer cluster.

Initially hypothesized causes of the Churchill County cluster included chemical exposures such as jet fuel or benzene, drinking water contamination by a radioactive isotope or naturally occurring arsenic, population mixing, or a new infectious agent, potentially associated with the nearby naval air station (NSHD 2003). Jet fuel has been associated with immune system effects in several studies (Harris et al. 1997a, 1997b, 2000, 2001; Jackman et al. 2002; Rhodes et al. 2003; Ullrich 1999), and benzene, a minor component of jet fuel, has been associated with increased rates of leukemia in occupationally exposed cohorts (Hayes et al. 2001; Savitz and Andrews 1997). The population-mixing theory holds that childhood leukemia can occur as a rare end result of some yet unknown infectious process, and large-scale mixing of urban and rural groups leads to increases in leukemia by allowing increased contact between potentially susceptible and infected individuals (Kinlen 1995). …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.