During which construction project did 250,000 workers reach their lifetime radiation limits ?
There is no known mechanism for this , and more notably , " the cities under study with the lowest radiation fallout have the highest increases of death rates in the 14 weeks following Fukushima , while the Californian cities that would have received larger doses saw a decrease in death rate growth " and concluded that " innumerable factors other than radiation " were likely responsible for the major part of the variation in US mortality around the time of the nuclear disaster .