The original report into the incident, the Penney Report, was ordered to be heavily censored by prime minister Harold Macmillan. Macmillan feared that the news of the incident would shake public confidence in nuclear power and damage British-American nuclear relations. As a result, information about the release of radioactive fallout was kept hidden by the government. It was not until 1988 that Penney's report was released in full. Partly because of this censorship, consensus on the extent of the long-term health impacts caused by the radiation leak has changed over time as more information on the incident has come to light. The release of the highly dangerous radioactive isotope polonium-210, which had been covered up at the time, was not factored into government reports until 1983, when it was estimated that the fallout had caused 33 cancer fatalities in the long-term. These deaths were attributed not only to thyroid cancer, but also to lung cancer. An updated 1988 UK government report (the most recent government estimate) estimated that 100 fatalities "probably" resulted from cancers as a result of the releases over 40 to 50 years. The government report also estimated that 90 non-fatal cancers were caused by the incident, as well as 10 hereditary defects.