Various forms of cancer kill roughly 565,000 Americans per year, while tobacco kills around 440,000, and obesity causes perhaps another 400,000 or more deaths. Approximately 1.7 million patients develop infections annually while undergoing treatment in U.S. hospitals, resulting in an estimated 99,000 deaths. These four causes account for roughly 1.5 million U.S. deaths per year, every year. A single organism, Clostridium difficile, causes some 450,000 infections and between 15,000 and 20,000 deaths per year.
Meanwhile, throughout the entire 20th century, bioterrorism killed a grand total of zero U.S. citizens, and just five to date in the 21st century.
Nevertheless, following the "Amerithrax" scare of October and November 2001 -- in which 22 people were sickened, of whom five died -- the U.S. government authorized $57 billion through September 2009 for biological weapons prevention and defense. The proposed current rate of annual authorization for this purpose is $7 billion, which is likely to continue in the future.