Women need to beware that while breast implants are safe, they are not meant to last a lifetime and could lead to problems later on, the top U.S. drug agency said Wednesday.

"Breast implants are not lifetime devices. The longer a woman has silicone gel-filled breast implants, the more likely she is to experience complications," the U.S. Food and Drug Administration said in a report.

Blame the potato chip. It's the biggest demon behind that pound-a-year weight creep that plagues many of us, a major diet study found. Bigger than soda, candy and ice cream.

And the reason is partly that old advertising cliche: You can't eat just one.

Smokers who are diagnosed with prostate cancer are more likely to have aggressive tumors and face a higher death risk from the disease than non-smokers, U.S. researchers said Tuesday.

Men who smoked at the time of diagnosis faced 61 percent higher risk of dying from prostate cancer and a 61 percent higher chance that the cancer would come back compared to men who never smoked, said researchers at the Harvard School of Public Health and University of California, San Francisco.

The World Health Organization published Tuesday new global guidelines for expanding AIDS treatment, focusing for the first time on homosexuals, who face discrimination in many countries.

"If we do not pay major attention to the epidemic in key populations, we will not be able to eliminate HIV" -- the virus that can lead to AIDS, said Gottfried Hirnschall, WHO director of the HIV/AIDS department.

High doses of drugs aimed at lowering cholesterol are linked to increasing numbers of new diabetes cases in patients, said a review of multiple studies on the topic published Tuesday.

However, those same high doses helped dramatically lower the incidence of cardiovascular problems in patients, leaving doctors to balance the benefits and risks according to each individual patient.

Scientists have found a possibly harmful fungus that grows in dishwashers, surviving high temperatures, aggressive doses of detergents and rinsing salts and both acid and alkaline types of water.

A black yeast called Exophiala dermatitidis was found with a cousin fungus, E. phaeomuriformis, in samples taken from dishwasters in 189 homes in 101 cities in six continents.

The U.S. government on Tuesday unveiled a new set of cigarette warnings with graphic images of a lifeless body, a scarred mouth and a blackened lung in order to highlight the health risks of smoking.

"Beginning September 2012, FDA will require larger, more prominent cigarette health warnings on all cigarette packaging and advertisements in the United States," the U.S. Food and Drug Administration said on its website.

Hong Kong has declared an outbreak of scarlet fever, an illness potentially fatal among children, after hundreds were infected in the teeming city, the government said Tuesday.

A seven-year-old girl in the southern Chinese city died late last month while there have been more than 400 cases so far this year, a Centre for Health Protection spokesman told Agence France Presse Tuesday.

A team of Swiss and French scientists published a study on Monday that suggests the rocking motion of a hammock improves sleep quality and helps people get to sleep faster.

The study included 12 male volunteers who were not habitual nappers but who agreed to try an afternoon snooze on both a stationary bed and a rocking bed while machines scanned their brains, eye and muscle movements.

U.S. regulators said Thursday that the label on Pfizer's anti-smoking drug Chantix must be changed to warn of a slightly higher risk of heart problems in patients who already have cardiovascular disease.

The drug, also known as varenicline, was shown in a clinical trial of 700 smokers to be associated with an elevated risk of heart attack, angina, and clogged arteries in some patients when compared to a placebo.