However, the yearly number of severe accidents substantially increased in non-OECD countries whereas it remained stable or decreased within OECD member countries. While the first had practically negligible radiation-exposure related health and environmental consequences, the two others had significant radiation-exposure related health and environmental consequences, and all three had from small to very large social and economic impacts. The Chernobyl accident, for instance, caused 31 immediate fatalities, and approximately 6 000 thyroid cancers (fatal in 15 cases).