Q: Can you explain why my fingers often feel numb and look white when I am out in cold weather or rinse dishes in cold water?
A: Your description fits the symptoms of Raynaud's phenomenon, a fairly common condition that particularly affects women less than 40 years old.
The arteries in the fingers normally constrict after exposure to cold and sometimes when emotional stress is excessive in people with Raynaud's. Full-blown attacks are characterized by three stages. First, the fingers turn pale as circulation is cut off. Next, they turn blue as a result of blood pooling in capillaries.
Finally, when the spasm subsides, blood rushes into the fingers, which then appear bright red. These episodes are frequently associated with numbness, tingling and pain.
Raynaud's phenomenon may result from narrowing of the arteries; repeated trauma to the blood vessels from holding vibrating instruments; drug reactions; or as a manifestation of some underlying disease, such as scleroderma, rheumatoid arthritis, lupus or certain blood disorders.
You should see your doctor to be sure your symptoms are not caused by one of these problems. When no underlying cause can be identified, the condition is referred to as Raynaud's disease, which usually has no serious long-range affects. The best "treatment" advice is to avoid cold, wear warm gloves and ask someone else to wash the dishes! There are several medications that may also alleviate the symptoms.
Q: Can I get AIDS from kissing a person who has the infection?
A: No. Many people are afraid that HIV-1, the virus that causes AIDS, can be transmitted by saliva. However, there is no documentation that contact with saliva can cause an HIV-1 infection. AIDS is not acquired from kissing, human bites, being spat upon, sharing toothbrushes or cigarettes, or carrying out cardiopulmonary resuscitation.
HIV-1 can, of course, be transmitted by all forms of unprotected sexual activity or from contaminated needles. An infected mother also can transmit HIV-1 to her fetus and by breast-feeding her child.
Q: Is the risk of cancer increased in people who live near power lines or are exposed to a large number of electrical appliances in the home?
A: Both electric and magnetic fields (together called electromagnetic fields, or EMFs) are generated by anything that carries an electrical current. Only a small fraction of the electrical components of an EMF can penetrate a wall or the skin. In contrast, magnetic fields can pass through most matter without losing strength. The EMFs most people encounter are quite weak.
Great concern was generated by a 1979 study that reported that children in Colorado who lived near a power line had a two- to three-fold increase in their risk of developing cancer. Most subsequent studies have also shown an increased incidence of cancer in children exposed to power lines, but the increase is much smaller than in the initial study. Researchers have not found any increase in cancer in adults living near power lines.
However, telephone linemen, electricians and others in electrical jobs are at higher risk for cancers, especially brain tumors and leukemia. It is not clear whether the greater risk is related to EMFs, because these workers are often exposed to cancer-causing chemicals as well.
Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine and associate dean for academic affairs at the