"There is no dispute that millions of Americans received polio vaccines that were contaminated with the virus called Simian Virus 40, or SV–40. There also is no dispute that SV–40 is capable of causing cancer, but there is a major dispute as to how many Americans may have received the contaminated vaccine, with estimates ranging from 4 million to 100 million people. There is also a major dispute as to when the polio vaccine supply got cleaned up. In addition, nobody knows how many people got sick or died because of the contaminated vaccines."
The ‘Unknown’ About Polio Vaccine: SV40 and Cancer