appeared in the Journal of Radioanalytical and Nuclear Chemistry, Vol. 243, No. 2 (2000) 467–472.During the electronic submission of the paper the file was damaged, and parts were left out. In order to correct this, we publish the correct paper as a whole.Iodine-129 may be no radiation hazard but it is a useful marker. Animal thyroids concentrate the isotope to 4 orders of magnitude greater than the intake. This results in a potential biological and physical indicator of radioactive contamination. Since 1943, 129I/127I ratio in animal thyroids from the Northern Hemisphere has increased 2 to 5 orders of magnitude. Since 1985, thyroids of deer, living near a nuclear reprocessing facility have contained 129I which is 3 to 7 orders of magnitude greater than pre-nuclear levels. Limited measurements of 129I in thyroids from the Southern Hemisphere have shown little increase. An appendix is presented to show that 129I may be helpful to evaluate past radiation hazard from fission products.