A cancer “hot spot” is a region with an unusually high incidence of either a single cancer or a spectrum of cancers. The search for potential causes is complex, expensive and often inconclusive.
Years of exposure to a cancer-causing agent (carcinogen) may be necessary before a malignancy occurs. During that interval a person may move to another part of the country, and the link to the causative agent may be obscured. A factory producing carcinogens may close and leave behind toxic wastes that may pollute soil and water for many years.
If a manufacturing or commercial enterprise is suspected of releasing carcinogens into the air or water, affected residents and their families must battle lobbyists and corporate lawyers to prove their case.
In the 1970s, multiple cases of liver and bladder cancer among residents of Sand Mountain, a rich agricultural region of Northeast Alabama, were linked to the pesticide Heptachlor (now banned). Extensive aerial spraying of crops with Heptachlor led to accumulation of the chemical in the groundwater of the region. Samples of wellwater contained concentrations of the chemical that far exceeded “safe” limits. Cancer epidemiologists sometimes encountered resistance from residents who feared loss of jobs if they cooperated with the scientists. Extension of waterlines to homes from noncontaminated sources corrected the problem.
In late 2019, residents of four counties in Southwestern Pennsylvania demanded an investigation by state officials of a an unusually high incidence of Ewing sarcoma, a rare cancer of bone that typically affects teens to young adults. Thirty-one cases occurred in the four counties from 2006 to 2017. A spectrum of other cancers involving bone, muscle, liver and bone marrow affected young residents in the region. Residents linked the outbreak to the high concentration of fracking wells – more than 3,500 – in the counties. Industry officials denied any link. An extensive investigation is underway.