Agronomic factors affecting polonium-210 and lead-210 levels in tobacco. II. Varieties and curing methods

Tobacco seedlings accumulated Pb210 and Po210 to a concentration much higher than that found in the soil. The levels of these radioelements decreased as the plants grew. Only minor differences were observed in harvested leaves of two flue-cured varieties - Coker 319 and Virginia Bright Leaf. The Pb210 and Po210 content in the seeds are in much lower levels than those in the respective leaves produced from the same plant. Neither of the two methods of flue-curing - a closed system with wood or an open system with kerosene - resulted in significant differences in radioisotope levels of cured leaf. Pb210 and Po210, if present in the combustion products of wood, were trapped in or exhausted through the flue pipes and were not deposited on the tobacco. Kerosene, because it contains little radioactivity, would not contribute much to the Pb210 level of cured leaf when fully exposed to products of combustion in an open system