The tsunami that struck Japan in March 2011 incapacitated the Fukushima Daiichi nuclear plant, led to releases of radioactive material and left the nation reeling. Now, the World Health Organization (WHO) reports an increased estimated risk for some cancers for those located in the most contaminated parts of the Fukushima Prefecture and for about one-third of the emergency workers who responded to the disaster.

For the general population both inside and outside of Japan, however, WHO reported no observable or anticipated increase in cancer risk.

“The primary concern identified in this report is related to specific cancer risks linked to particular locations and demographic factors,” says Dr. Maria Neira, WHO Director for Public Health and Environment. “A breakdown of data, based on age, gender and proximity to the nuclear plant, does show a higher cancer risk for those located in the most contaminated parts. Outside these parts – even in locations inside Fukushima Prefecture – no observable increases in cancer incidence are expected.”

Radiation Exposure Among Workers

According to the report, around two-thirds of emergency workers who were inside the nuclear plant are estimated to have cancer risks in line with the general population, while one-third is estimated to have an increased risk. Workers may have been exposed to radiation through internal exposure from inhalation of radioactive material in the workplace; external exposure from radioactive material deposited in the workplace; external exposure from radioactive material suspended in the workplace air; external exposure from proximity to radiation sources within the damaged reactors; or external contamination from radioactive material deposited on the skin or clothes.

The assessment of emergency workers was based on the occupational doses estimated by the operator TEPCO. The exposure assessment focused on 23,172 emergency and mitigation workers, including 5,639 TEPCO employees and 17,533 contractors. Other types of workers who may have been exposed to radiation, including firemen, police officers, rescue workers, volunteers and government employees, were not included in the assessment.

“Based on the results of the internal dose estimation, TEPCO concluded that workers with the highest internal doses were those working in a central control room,” the report notes. “Stable iodine tablets were distributed to emergency workers beginning 13 March 2011. So far, no health effects have been observed for workers exceeding the dose limits.”

All estimates of workers’ doses are considered preliminary as data collection and analysis continues.

One-Third of Fukushima Emergency Workers May Have Increased Cancer Risk
EHS Today