Small amounts of caesium-134 and caesium-137 were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Goiânia accident and the Chernobyl disaster.
smˈɔːl ɐmˈaʊnts ʌv sˈiːsiəm wˈʌnhˈʌndɹɪd θˈɜːɾi fˈoːɹ ænd sˈiːsiəm wˈʌnhˈʌndɹɪd θˈɜːɾi sˈɛvən wɜː ɹᵻlˈiːst ˌɪntʊ ðɪ ɛnvˈaɪɹənmənt dˈʊɹɹɪŋ nˌɪɹli ˈɔːl nˈuːklɪɹ wˈɛpən tˈɛsts ænd sˌʌm nˈuːklɪɹ ˈæksɪdənts, mˈoʊst nˈoʊɾəbli ðə ɡˈɔɪənˌiə ˈæksɪdənt ænd ðə tʃˈɜːnəbˌɪl dɪzˈæstɚ.