Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:
No Proof Virus Causes Chronic Fatigue Syndrome: Study
There's no evidence that a virus called XMRV causes chronic fatigue syndrome, says a British study that challenges recent research suggesting the virus could be responsible for the debilitating condition.
Imperial College London researchers analyzed blood samples from 186 patients with CFS and found that none of them had the virus, BBC News reported.
"We are confident that are results show there is no link between XMRV and chronic fatigue syndrome, at least in the U.K.," said investigator Professor Myra McClure.
Experts said the study findings, published in the journal PLoS One, will be bitterly disappointing to many patients who'd pinned their hopes on drugs to fight XMRV, BBC News reported.
Full-Body Airport Scanners No Health Threat: Experts
While some are concerned about cumulative radiation exposure from full-body scanners used for airport security, most experts say such fears are unfounded, according to ABC News.
Use of the scanners is expected to increase in the wake of the alleged failed bombing attempt on an Amsterdam-to-Detroit flight on Christmas Day.
The full-body scanners use a technology called backscatter X-rays, which deliver a low dose of radiation, explained Dr. James Thrall, chairman of the American College of Radiology and chairman of radiology at Massachusetts General Hospital in Boston.
"Moreover, the individual X-rays themselves are very low energy, and unlike the X-ray spectrum that we use in medicine, the backscatter X-rays don't really penetrate to the organs in the body," he told ABC News.
Thrall said a person would have to "take hundreds and hundreds of trips requiring screening to even reach what would be considered a negligible dose" of radiation.
No Big Change in FDA Drug Approvals Last Year
The number of drugs approved last year by the U.S. Food and Drug Administration was about the same as in 2008, and the number of warnings issued by the agency decreased, according to figures released by the investment research group Washington Analysis.
In 2009, the FDA approved 26 first-of-a-kind prescription drugs, compared with 25 in 2008. An FDA spokeswoman wouldn't confirm or comment on the number of drugs approved last year, the Associated Press reported.
Washington Analysis also said the FDA last year added 31 new or updated "black box" warnings to drugs already on the market, compared with 56 boxed warnings in 2008.
The drug industry had been worried that the Obama administration would take a much tougher stance on drug safety than the Bush administration, but these figures suggest a moderate approach, the AP reported.
Head Blows Don't Cause Brain Damage: Ex-NFL Doctor
Despite tough questioning by members of Congress, the former head of the NFL's concussion committee insisted Monday there is no proven link between football head injuries and brain disease.
"There is not enough valid, reliable or objective scientific evidence at present to determine whether or not repeat head impacts in professional football result in long-term brain damage," New York City neurologist Dr. Ira Casson said in prepared testimony delivered to the House Judiciary Committee, CBS News and the Associated Press reported.
Casson, who resigned as co-chair of the NFL's committee on mild brain injuries in November, said it was wrong to suggest that the committee had ignored the problem of head injuries among football players.
His stance drew scorn from House Judiciary Committee members.
"I find it really ridiculous that he's saying that concussions don't cause long-term cognitive problems," said Rep. Linda Sanchez, D-Calif., CBS/AP reported. "I think most people you ask on the street would figure that repeated blows to the head aren't good for you."