Cancer Clusters: Findings vs. Feelings

See also http://www.medscape.com/viewarticle/442554

Executive Summary

The issue of cancer clusters, which has been in the spotlight recently, is plagued by a wide disparity between public perceptions and scientific findings. Movies like Erin Brockovich and A Civil Action have led the public to think that industrial pollution in the environment is causing local "cancer clusters" where cancer cases are more prevalent due to cancer-causing chemicals.

There are many scientifically documented instances in which chemical exposure has caused cancer in humans, but these have generally not been purely environmental. Contamination in the water supply or air causing residents of a neighborhood to develop cancer, although popularly thought to be a common occurrence, has rarely been documented through scientific investigation. Instead, the clusters that scientists have been able to attribute successfully to a particular cause have been occupational such as workers in a factory developing a particular type of cancer as a result of exposure to one of the chemicals they handle every day or have been linked to a particular medicine, or to behaviors such as smoking or sunbathing. The evidence for environmental contamination causing cancer, however, is sparse. There is some indication that chemicals dissolved in drinking water may elevate the risk of gastrointestinal and bladder/urinary tract cancers, and that living next to a smelter or other "point source" of air pollution may elevate risk of lung cancer. The many efforts that have been made to demonstrate links between other types of cancer and environmental contamination have not conclusively identified such links.

Science does not support the popular image of traces of chemical contamination elevating the cancer risk of everyone who lives in a neighborhood regardless of where they work, what sort of lives they lead, and what hereditary influences may predispose them to cancer. The absence of conclusive scientific evidence in this area may be partially explained by the myriad challenges that bedevil cancer cluster investigations challenges that are explored in this report.

This report discusses the potential cancer clusters in Toms River, New Jersey and Long Island, New York, because they contain many elements typical of cancer cluster investigations and have received considerable media attention.