A procedure for detecting childhood cancer clusters near hazardous waste sites in Florida

Despite over 20 years of research on childhood cancer clusters and hazardous waste sites, little evidence has been produced to indicate a causal relationship. Nevertheless, the perception of a childhood cancer cluster being located near a hazardous waste site can raise fear and uncertainty, and it demands attention from health officials. To investigate this public health concern, the author used the spatial-scan statistical software SaTScan to detect childhood cancer clusters and their proximity to National Priority List (NPL), or Superfund, sites in Florida. In the ecological study reported here, "most likely" clusters were defined as those with a p-value of < .05. Distance served as a proxy for exposure; a geographical information system (GIS) was used to determine the number of clusters within a predetermined distance of an NPL site. Spatial clusters were found to occur randomly throughout the state, with most clusters being identified in the more populated counties, and clusters less likely to occur near an NPL site. This article attempts to explain the utility of an emerging public health surveillance tool for detecting cancer clusters near hazardous waste sites. Despite several epidemiological limitations of the study, as well as the fact that there are other environmental exposure hazards such as Toxic Release Inventory facilities and landfills, the SaTScan program proved useful as a surveillance tool for generating more in-depth studies.