Tritium (symbol T) is produced in the upper atmosphere by neutron cosmic rays primarily through the 14N(n,T)12C and 16O(n,T)14N reactions. Tritium has a half-life of 12.3 years and decays by emitting a beta-particle with a maximum energy of 18.6 keV. Tritium exists in nature almost exclusively as HTO. and in the continental surface waters and the human body it has an atomic T:H ratio of 3.3 x 10^-18. Since the human body is about 10% hydrogen by weight, estimate the tritium activity (Bq) in a 100-kg person.