210Po in the Environment: Reassessment of Dose to Humans

Abstract

Significant efforts have been made by the International Commission on Radiological Protection (ICRP) to establish a reliable basis of equivalent and effective doses due to radionuclides. The ICRP over years has been updating the dose coefficients to include recent developments and make it more realistic. This perspective highlights some issues that warrant updating the methodology used for estimating 210Po dose to humans. The need to underpin these dose coefficients with ever-increasing literature has encouraged us to share the observation on the significant loss of 210Po due to seafood cooking, considering the loss due to cooking warrants changing the factor for the dose from seafood ingestion. Most dose assessment approaches use whole-body concentration, while most 210Po is present in the liver and digestive system that often are not part of the edible portion. The other factor is the extremely high 210Po concentration in aerosols as a result of coal and oil-fired power plants, forest fires, and volcanic activities, especially in the inhalable fraction. The 210Po/210Pb concentration ratio in the Gulf was observed to be between 1.6 and 1.9 in contrast to the 0.1 ratio observed in non-impacted areas. This reassessment of the inhalation dose is also relevant globally due to increasing incidences of forest fires where a much higher than 0.1 210Po/210Pb ratio is expected and will result in a significant inhalation dose.