— -- The breach of a tunnel that houses contaminated radioactive materials at the Hanford Nuclear Reservation has drawn attention to potential risks around nuclear radiation exposure, including cancer concerns long-cited in the surrounding community, which has dubbed the scar left behind following thyroid surgery "The Hanford Necklace."
The Hanford site in Washington State made plutonium for the atomic bomb dropped on Nagasaki, Japan, according to the Associated Press. It is about half the size of Rhode Island, according to the AP. The facility was built as part of the Manhattan Project and produced nuclear materials for the military for decades. It is now the nation’s largest depository of radioactive defense waste, with 56 million gallons.
On Tuesday, during a routine inspection, a 20-foot-wide hole was discovered in a tunnel that feeds into a longer tunnel “that contains 28 rail cars loaded with contaminated equipment," the Hanford Joint Information Center said in a statement.
The routine inspection occurred during a massive radioactive waste cleanup that has been underway since the 1980s, which costs more than $2 billion a year, according to Associated Press. The site made plutonium for nuclear weapons for decades, according to the AP.
Though no sign of "radiological release" has been found and no workers have been injured, according to Emergency Center Spokesperson Destry Henderson, people working at and living near the Hanford nuclear facility have been concerned about increased risk of thyroid cancer and other health issues for decades. The thyroid is one of the highest risk organs because thyroid tissue is extremely sensitive to radiation compared to other tissues.
Media reports over several years have documented stories about the alleged cancer cluster and the U.S. Centers for Disease Control and Prevention (CDC) initiated a long-range study. The concerns over cancer rates and the known exposures to the radioisotope called iodine-131 in the 1940's were tracked in the 13-year study published in 1999, funded by the CDC and carried out by the Fred Hutchinson Cancer Research Center.
The study did not find an increased risk of thyroid cancer and other thyroid issues for the 3,440 people near the Hanford site who were studied.
However, after it was published, the study was later criticized for some of the methods used by researchers. A panel convened by the National Academy of Sciences gave high marks for the study's execution and design, but found researchers had "presented the results in a way that made them appear more conclusive than was warranted."
The researchers re-examined some of their data in response to these concerns, but made no significant changes to their findings.
"We analyzed the data a number of ways, and the results were the same," Scott Davis, Ph.D., Fred Hutchinson’s principal investigator for the study, said in a final report published about the study in 2002.
Concerns over potential health risks have persisted. Last year, Washington Attorney General Bob Ferguson filed a lawsuit contending vapors from nuclear waste storage tanks pose a serious risk to Hanford workers, according to the Associated Press. The attorneys for the Energy Department have reportedly said that there is no evidence provided that shows workers have been harmed by vapors, according to the AP.
Dr. Robert Emery, vice-president for Safety, Health, Environment and Risk Management and professor of occupational health at UT Health in Houston, who is not involved with the Hanford response, said that with the most recent incident, monitors will be closely watching for any sign of contamination from radioactive materials.
"The big concern would be was any radioactive contamination released in the air or in the soil or perhaps in the waterways," he explained.
But the risks for those routinely working in or near nuclear facilities are not clear.
For those charged with cleaning up the area, Emery said they will need to wear protective suits along with a dosimeter to monitor their exposure to radiation. People working with radioactive materials are supposed to be monitored for the duration they work around these materials.
Under an occupational health program, Emery said, an employee would be checked for signs of excess exposure to radioactive material and their thyroid would be monitored to help diminish any risk.
Dr. Michael Harbut, a professor of medicine at Michigan State University, who is not involved in the Hanford response, said ideally employees at a nuclear facility should be provided ample protection from excessive radiation exposure.
"The workers should not be exposed to more radiation than those in the community, ideally these levels should be the same," he said.
Radiation has long been associated with a host of health risks and numerous cancers, especially thyroid cancer. However, radiation exposure can occur from a variety of sources, from exposure to nuclear defense and energy materials to natural and everyday sources like the sun.
Survivors of atomic bombings and nuclear accidents like Chernobyl who are exposed to extremely high levels of radiation have shown a clear risk for certain cancers. Children near Chernobyl were found to be more likely to have thyroid cancer, especially if they were deficient in iodine. Chernobyl clean-up workers were found to be at increased risk for leukemia, according to the American Cancer Society.
Less dramatic sources of radiation have also been associated with increased risk. Nuclear testing done above ground in the 1950's may have increased risk for thyroid cancer in some children due to exposure to radioactive iodine in milk, according to the American Cancer Society. Radiation from medical tests such as X-rays or CT scans has also been associated with increased risk of some cancers, they added.
ABC News' Karma Allen and Courtney Connley contributed to this report.