Future health problems directly linked to radiation exposure from the 2011 Fukushima nuclear disaster in northeastern Japan are "unlikely to be discernible," a U.N. panel has stated.
A reported increase in the number of local children diagnosed with thyroid cancer is not the result of radiation exposure, the United Nations Scientific Committee on the Effects of Atomic Radiation said in a report it released Tuesday.
The increase in thyroid cancer is believed to have originated from "ultrasensitive screening procedures that have revealed the prevalence of thyroid abnormalities in the population not previously detected," the report said.
Fukushima Prefecture has been examining local children for thyroid cancer after the crisis as radioactive iodine released in nuclear accidents tends to accumulate in thyroid glands, particularly in young people.
The report said the incidence of thyroid cancer which could be inferred from the estimated radiation exposure is also "not likely to be discernible" in any age groups, including those exposed in utero.
In the 1986 Chernobyl disaster, a noticeable increase in thyroid cancer cases was detected among children in the affected area around five years after the incident.
The committee added that in the general public there has been no credible evidence of excessive congenital anomalies, stillbirths, preterm deliveries or low birthweights related to radiation exposure.
The U.N. committee also concluded that no apparent increase in the incidence of illnesses such as leukemia and thyroid cancer among workers at the Fukushima plant could be attributed to their radiation exposure.
In the report, average effective radiation doses received by 1-year-old infants who were evacuated from areas near the plant were estimated to have ranged from 0.15 to 7.8 millisieverts in the first year following the disaster.
It also found average effective radiation doses over the 10-year period to those who were 1-year-old at the time of the crisis and continued to live in Fukushima Prefecture ranged from 0.22 to 14 mSv.
The International Commission on Radiological Protection sets radiation exposure under normal situations at 1 mSv per year.
As for damage on the environment, the U.N. panel said detrimental effects in some plants and animals have been observed in areas with enhanced radiation levels. Radionuclide concentrations in most monitored foodstuffs have declined rapidly following the accident, it added.
On March 11, 2011, a magnitude-9.0 earthquake and subsequent tsunami hit northeastern Japan, causing the Nos. 1 to 3 reactors at the Fukushima Daiichi nuclear plant to suffer core meltdowns.
Decommissioning work is still in progress and evacuation orders are in place in some areas even about a decade after the world's worst nuclear accident since the Chernobyl disaster.
The UNSCEAR compiled the latest report after validating more up-to-date information available through the end of 2019 to revise the previous 2013 report.
