Doctor's Orders: Oct. 3, 2005

THE RISKS OF BEING A GREASE MONKEY A Swedish study found that men working with mineral oils such as those found in asphalt or hydraulic or motor oils may increase their risk of getting rheumatoid arthritis by 30%. Exposure to the lubricants may trigger inflammatory processes that swell joint linings.

1 BILLION The number of people around the world who are overweight or obese, according to the World Health Organization. The heaviest populations include those in the U.S., Egypt, New Zealand, Turkey and the Western Pacific Islands.

HOW CLEAN IS YOUR SMILE? Periodontal disease, a dangerous infection of the gums that can result in tooth loss, generally begins in middle age. But in a new study, up to a quarter of people in their 20s who kept their wisdom teeth harbored this infection without knowing it. Even more sobering: pregnant women with the worst infections doubled their risk of having a premature baby.

OF CARROTS AND CANCER Vegetables, as everybody knows, are full of nutrients that help ward off disease. But in some circumstances, vitamins can do you harm. Take beta-carotene, for example. Found in carrots and spinach, this vitamin-A nutrient, if taken in pill form, is known to increase the risk of lung cancer in smokers and former smokers. Now a study of women shows that smokers taking beta-carotene may be at greater risk of colorectal, thyroid, ovarian and cervical cancers as well. --By Alice Park