Iridium-192 has accounted for the majority of cases tracked by the U.S Nuclear Regulatory Commission in which radioactive materials have gone missing in quantities large enough to make a dirty bomb.
ɪɹˈɪdiəm wˈʌnhˈʌndɹɪd nˈaɪnti tˈuː hɐz ɐkˈaʊntᵻd fɚðə mədʒˈɔːɹᵻɾi ʌv kˈeɪsᵻz tɹˈækt baɪ ðə jˈuː.ˈɛs nˈuːklɪɹ ɹˈɛɡjʊlətˌoːɹi kəmˈɪʃən ɪnwˌɪtʃ ɹˌeɪdɪoʊˈæktɪv mətˈɪɹiəlz hæv ɡɔn mˈɪsɪŋ ɪn kwˈɔntᵻɾiz lˈɑːɹdʒ ɪnˈʌf tə mˌeɪk ɐ dˈɜːɾi bˈɑːm.