Tobacco farmers use fertilizers that contain a naturally-occurring radionuclide, radium, to help crops grow. Cigarettes made from this tobacco still contain these radioactive elements. These elements settle in people’s lungs when they smoke cigarettes.
"The fertilizers that tobacco farmers use to increase the size of their tobacco crops contain the naturally-occurring radionuclide radium and its decay products. As the plant grows, the radon from fertilizer, along with naturally-occurring radon in surrounding soil and rocks, transfer into and on the plant and are later included in tobacco products made from these plants. Radon’s decay product, polonium-210, carries the most risk."