tokens: Romania was in the vicinity of the radioactive cloud at Chernobyl fallout , so we must deliberate whether the increased incidence of thyroid cancer in the age group 40 - 60 years is associated with radiogenicity ( iodine 131 ) given the fact that over has 35 years and the half - life of other radioisotopes like Caesium-137 and Strontium -90 is completed .