The Three Mile Island accident, which occurred in March 1979, represents a significant event in the history of nuclear power in the United States. This incident immediately raised widespread public anxiety, particularly concerning the potential for increased cancer rates among the population living nearby. This article explores the scientific investigations undertaken to address these concerns and what research has revealed about the accident’s long-term health implications.
The Three Mile Island Accident and Radiation Release
The Three Mile Island Unit 2 accident in March 1979 involved a partial meltdown of the reactor core, releasing radioactive gases into the atmosphere. The primary radioactive materials released were noble gases, such as xenon and krypton, along with some iodine. The amount of direct radiation exposure to the public from this release was generally considered low. Despite this low exposure, the release of radioactive materials fueled public apprehension, leading to concerns about a subsequent rise in cancer rates.
Early Health Concerns and Research Efforts
Following the Three Mile Island accident, there was immediate and widespread public fear regarding potential health impacts, especially the development of cancer. This public anxiety prompted various government agencies and academic institutions to initiate epidemiological studies and health monitoring programs. These early efforts focused on tracking cancer incidence and other health outcomes within the population residing near the Three Mile Island facility.
The President’s Commission on the Accident at Three Mile Island, appointed by President Jimmy Carter, concluded there would be no detectable cancers or genetically related instances of ill-health from the accident. Similarly, the Governor’s Commission on Three Mile Island agreed that accident health effects would be negligible. These initial assessments aimed to provide reassurance and inform future long-term health investigations.
Scientific Studies on Cancer Incidence
Major long-term epidemiological studies have been conducted to assess cancer rates in the population around Three Mile Island. The Columbia University study, led by Maureen C. Hatch, examined cancer incidence in relation to the accident releases. Published in the American Journal of Public Health in September 1990, this study confirmed that low exposure levels, estimated at an average of approximately 10 millirems with a projected maximum of 100 millirems, did not lead to an excess of cancer.
The Pennsylvania Department of Health also found no increased cancer risks for residents. Similarly, a National Cancer Institute study of cancer mortality rates around 52 nuclear power plants, including Three Mile Island, released in September 1990, found no link between the accident and increased cancer rates.
While most studies did not find a consistent, statistically significant increase in cancer rates directly attributable to the accident, some dissenting opinions have emerged. For example, a re-evaluation by Dr. Steven Wing suggested that cancer incidence, specifically lung cancer and leukemia, increased in areas estimated to have been in the pathway of radioactive plumes. However, other experts noted that factors like smoking may have contributed to the increased lung cancer risk cited in Wing’s study.
Understanding the Data and Public Health Impact
The low levels of radiation exposure to the public during the accident align with scientific studies finding no significant increase in cancer rates. The average local radiation exposure was estimated to be around eight millirem, comparable to a chest X-ray, with a maximum individual exposure of no more than 100 millirem. These exposure levels are relatively low when compared to typical background radiation or medical exposures.
The U.S. BEIR report on the Biological Effects of Ionizing Radiation stated that the collective dose equivalent from the Three Mile Island accident’s released radioactivity was so low that any estimated excess cancer cases would be negligible and undetectable. While scientific consensus points away from a widespread increase in cancer directly caused by the accident, public perception and concern can persist due to the nature of the event. The President’s Commission identified mental stress experienced by the general population and workers as the most significant health effect.