Fourteen residents of McCullom Lake Village, Illinois (population 1,000) have brain cancer. The incidence in the US population is 4 in 100,000. This is the largest brain cancer cluster identified in a non-occupational setting. In epidemiological terms, the chance that this is a coincidence is something like your chance of winning the lottery. It’s far more likely that the 14 victims share some sort of common link. The evidence in this case points to the vinyl chloride in the groundwater flowing into their wells from a nearby factory that made vinyl food wrap.
Aaron Freiwald is an attorney representing the cancer victims in a class action lawsuit against Rohm & Haas, which bought the suspect facility from the Morton Chemical Company in 1999. According to Freiwald, “By the time we are done with this case, the association between vinyl chloride and brain cancer is going to be much stronger. They are going to have to revise the way current text books discuss cancer risks associated with vinyl chloride.”
One critical factor in the case is the clear connection between the vinyl chloride and the cancers. It can be difficult to prove a specific chemical causes a specific cancer because so often people have multiple exposures to carcinogens. But, Lake McCollum is an isolated community. There are no other significant industrial sources of chemical contamination to which the 14 victims have been exposed. According to the International Agency for Research on Cancer (IARC), vinyl chloride is carcinogenic to humans and has been associated with brain cancer.
Improved methods of analyzing DNA allow scientists to compare cancer cells in ways not available in earlier cases – such as the case of vinyl chloride plant worker Dan Ross featured in the PBS documentary Trade Secrets, and HBO’s Blue Vinyl. This new DNA analysis shows that the damage to brain tissue among the Illinois victims is strikingly similar, and that this pattern is different from other types of brain cancers – further evidence of a common local cause.
Freiwald is most excited by what his investigation has uncovered about industry-sponsored studies of vinyl workers. These have been the backbone of the vinyl industry’s defense that there is at best a “weak statistical correlation” between vinyl chloride exposure and brain cancer. The industry studies have long been criticized for having diluted the surveyed worker population with employees unlikely to have been exposed to Vinyl Chloride. “Our questioning of industry experts under oath,” says Freiwald, “has brought to light evidence that is going to strike at the heart of the whole industry’s defense of vinyl chloride.”
In depositions taken as part of this case, Freiwald says that industry experts acknowledged that had just one more case of cancer been identified in the worker population that was studied, the conclusion would have changed from a “weak statistical correlation” at best to a “statistically significant” correlation.
The McCollum case reminds us that the many problems associated with chlorinated materials, such as PVC plastic, are likely under-estimated, masked by the limits of scientific investigations to date, and obscured by the intensive cigarette science campaigns of its manufacturers. This new evidence reinforces the US Green Building Council task force finding that PVC is consistently among the worst materials for human health impacts.
 According to Freiwald, the number of glioblastomas (the dominant brain cancer in this group) is 3-4 per 100,000. The number of oligodendrogliomas, the second and related type of brain cancer among the victims, is 0.3 cases per 100,000. The number for all "brain and CNS" cancers, which is a more inclusive group of diseases, is 7 in 100,000.
 The chemical alleged to have been released into the Lake McCollum’s groundwater is known as dichlroroethylene, or 1, 1-dce, which undergoes reductive dechlorination to vinyl chloride in groundwater and landfills.