Hitoshi Nishimura/Getty Images(NEW YORK) -- The head of the Bureau of Prisons union has written to President Joe Biden asking him to seriously consider the impact staffing shortages are having on the nation's federal prisons. "The current staffing shortage within our agency have reached a critical level, placing an unsustainable burden on our existing workforce, and compromising the safety and security of both staff and inmates," president of the Council of Prison Locals 33, Brandy Moore-White wrote to Biden in a letter obtained by ABC News. Moore-White represents nearly 30,000 feder...