The scientific community has been unable to reach a consensus on the cause or causes of the leukemia cluster in Woburn. Studies examining the association between the groundwater and incidences of leukemia are conflicting or inconclusive. Additionally, the American Cancer Society reports that the form of childhood leukemia found in most of the diagnosed Woburn children, ALL, has not been linked to chemical exposure, including chemical contamination of groundwater.
In June 1988, the EPA Office of Health and Environmental Assessment released a status report of an assessment conducted by its Woburn Workgroup. The Workgroup concluded that the excess leukemia incidence in Woburn may be real, but that the reported link between contaminated drinking water and excess leukemia was tenuous. The evidence in Woburn was considered by the Workgroup to be inadequate to establish or refute a causal (i.e., cause-and-effect) relationship between the contaminated drinking water and an excess risk of leukemia. In conclusion, the EPA Workgroup came to the opinion that (1) there may be an increased incidence of childhood leukemia in Woburn and (2) it cannot be determined whether the cases of leukemia were caused by drinking water or other risk factors.
[Source: http://www.civilaction.org/faq.htm]