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Q Do cell phones give off dangerous waves that can cause cancer and other serious problems?

C.H., Lidgerwood, ND

A Most experts on this subject are doubtful that cell phones--or other electronic devices such as computers, TVs, radios, or microwaves--cause cancer. Scientists point out that mobile phones operate in a frequency that produces a type of radiofrequency (RF) energy that is different from the radiation exposure you get from a medical X-ray, which can present a health risk at high doses. Nevertheless, some scientists feel that further research into the effects of cell phone radiation is worthwhile. And yes, cell phone use can cause other serious problems. One scientist told FDA Consumer magazine that he believes there is no risk of cancer even for a person speaking hours a day on a cell phone. "Go right ahead," he said, "but please, please, please don't use it while driving. That is dangerous."

Q What is the best way to clear up a headache quickly? What is the best medicine for it?

S.R., Roswell, NM

A About 90 percent of all headaches are tension/ muscle contraction headaches. Stress triggers the pain, causing the muscles of the neck, face, and scalp to contract. The contraction stimulates pain-sensitive nerves called nociceptors to send "we hurt" messages to the brain. Identifying the different kinds of stress that can set off a headache can help treat it. Some people get a headache when they miss a meal and are very hungry. (That's easy to take care of!) Headaches also can be caused by a combination of reading or working at a computer for a long period of time and sitting with a slumped posture with the chin down. Writing or reading under poor light or holding a phone between the shoulder and chin for a prolonged time can also cause a headache.

Taking a break from the activity may be the first step in clearing up the headache. Applying a warm compress, taking a warm bath or shower, and trying relaxation techniques can also bring relief.

Medications that can help include analgesic drugs such as acetaminophen, but check with your parents or the school nurse before you take them. Never use prescription pain medication that has been prescribed for someone else.

Q What is the reason that the minimum legal drinking age is 21 in the United States?

D.S., Wilmington, DE

A In 1984, the U.S. Congress passed the National Minimum Purchase Age Act. The act requires all states to set their purchase and public possession of alcohol age at 21 or risk losing federal highway funds that they need to maintain their highways. Back at the end of Prohibition (when the manufacture and sale of all alcoholic beverages was illegal) in 1933, nearly all states set the minimum legal drinking age (MLDA) at 21. Between 1970 and 1975, 29 states lowered that age to 18, 19, or 20. Studies showed, however, that motor vehicle accidents increased significantly among teens when the drinking age was lowered. This fact was a major reason for restoring the MLDA to 21. Since then, further studies have shown that the MLDA of 21 saves the lives of more than 1,000 teens each year.

Q How does cross-training help athletes? What is a good cross-training program?

N.J., Spokane, WA

A Cross-training is doing two or more types of exercise during one session, in the course of a day, or on alternate days. Cross-training is considered beneficial by many sports fitness experts because it adds variety to workouts, develops the entire body, and can help prevent injuries. One example of cross-training is doing an aerobic exercise, such as jogging or biking, for 20 or 30 minutes, followed by a muscle-building exercise such as weight training. Other types of exercise include stretching and yoga to increase flexibility; sprinting to improve anaerobic fitness, which involves intense bursts of muscle activity; and sit-ups, push-ups, and pull-ups to build muscle endurance.

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