- The radioiodines released by the accident delivered radiation doses to the thyroid glands of people, especially children, in heavily contaminated areas. The short-lived iodines (particularly iodine-131 with a half-life of 8 days) were ingested in foodstuffs, mainly contaminated milk, and also inhaled from the initial radioactive cloud. Radioiodines accumulate in the thyroid, thus irradiating the gland from the inside.
- A sharp increase in thyroid cancer among children from the affected areas is the only major public health impact from radiation exposure documented to date. At the end of 1995, about 800 cases in children under 15 years of age had been diagnosed, mainly in the northern part of Ukraine and in Belarus. Three children among the diagnosed cases are known to have died of the cancer by then-which generally can be successfully treated surgically and by medication.
- Based upon the current epidemiological projections, an increase in the incidence of thyroid cancer in adults who received radiation doses as children could occur, with the total number of cases possibly in the order of a few thousands.
- The incidence of thyroid cancer among children born more than six months after the accident has remained at the low levels expected in unexposed populations. This confirmed that the risk of thyroid cancer was only increased among those receiving high thyroid doses in 1986 and not among those exposed only to the continuing low levels of exposure since then.