The risks of cancer as a result of the Fukushima-Daiichi nuclear accident in Japan are low and experts do not foresee any increase in cancer rates above baseline rates, says a report from the World Health Organisation released today.
People exposed to the highest doses of radiation during and after the March 2011 accident may have a slightly higher risk of cancer that is so small it probably won’t be detectable, according to the almost-200-page report.
The WHO said the “comprehensive assessment by international experts” on the health risks associated with the Fukushima-Daiichi nuclear power plant disaster in Japan has concluded that, for the general population inside and outside of Japan, the risks of cancer are low and “no observable increases in cancer rates above baseline rates are anticipated”.
The WHO report ‘Health Risk Assessment from the nuclear accident after the 2011 Great East Japan Earthquake and Tsunami based on preliminary dose estimation’ noted, however, that the estimated risk for specific cancers in certain subsets of the population in Fukushima Prefecture has increased and, as such, it calls for long term continued monitoring and health screening for those people.
Experts estimated risks in the general population in Fukushima Prefecture, the rest of Japan and the rest of the world, plus the power plant and emergency workers that may have been exposed during the emergency phase response.
Dr. Maria Neira, WHO director for public health and environment, said the primary concern identified in the report is related to “specific cancer risks linked to particular locations and demographic factors”.
She said: “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.”
In terms of specific cancers, for people in the most contaminated location, the estimated increased risks over what would normally be expected are:
- All solid cancers: the normally expected risk for all solid cancers combined in females over lifetime is 29 percent and the additional lifetime risk assessed for females exposed as infants in the most affected location is around one percent.
- Breast cancer: the normally expected risk of female breast cancer over lifetime is 5.53 percent and the additional lifetime risk assessed for females exposed as infants in the most affected location is 0.36 percent.
- Leukaemia: the normally expected risk of leukaemia in males over lifetime is 0.60 percent and the additional lifetime risk assessed for males exposed as infants in the most affected location is 0.04 percent.
- Thyroid cancer: the normally expected risk of thyroid cancer in females over lifetime is around 0.75 percent and the additional lifetime risk assessed for females exposed as infants in the most affected location is 0.50 percent.
For people in the second most contaminated location of Fukushima Prefecture, the estimated risks are approximately one-half of those in the location with the highest doses, the report says.
The report includes a section on “the special case” of the emergency workers inside the Fukushima-Daiichi plant. Around two-thirds of emergency workers are estimated to have cancer risks in line with the general population, while one-third is estimated to have an increased risk.
The report says the Fukushima-Daiichi accident has not resulted in acute radiation effects among workers. None of the seven reported deaths among workers is attributable to radiation exposure.
The report notes that the radiation doses from the damaged nuclear power plant are not expected to cause an increase in the incidence of miscarriages, stillbirths and other physical and mental conditions that can affect babies born after the accident.
It says the relationship between radiation exposure and lifetime risk of cancer is complex and varies depending on several factors, mainly radiation dose, age at time of exposure, sex and cancer site. These factors can influence the uncertainty in projecting radiation risks, in particular when assessing risks at low doses.
Non-cancer health risks were assessed but not quantitatively estimated. The psychosocial impact and potential mental health conditions that might be associated with the accident are briefly discussed in the report, but not assessed for risk.