CARSON CITY, Nev. -- Valley residents are not the only ones angered by a clinic exposing 40,000 former patients to hepatitis C -- one state senator is now asking Congress to get involved.

In a letter to four U.S. senators, state Rep. Shelley Berkley asked Congress to investigate the Endoscopy Center of Southern Nevada.

The center is contacting some 40,000 ex-patients after using syringes contaminated with hepatitis C, leaving the people exposed to the virus.

"Transmission of hepatitis B through exposure to blood or other bodily fluids from infected patients and/or health care workers is a serious problem that can and must be prevented," Berkley said. "Congress should convene hearings on this issue to highlight the rising outbreaks and prevalence of infections acquired by patients during the course of treatment from unrelated conditions."

Officials from the Southern Nevada Health District, the Centers for Disease Control and Prevention and center workers are still investigating how contaminated syringes were used by anesthesiologists.

Physicians recommend those people who had procedures done between March 2004 and January 2008 be tested for hepatitis B and C, as well as HIV.