Q. I use rubbing alcohol on my feet after taking a bath. Lately, I've started wondering whether this chemical gets into the body to any significant degree and what its possible toxic effects are, if any.

A. Small amounts of rubbing alcohol, also called isopropyl alcohol, don't go through your skin to any significant degree. The main danger lies in accidentally drinking this chemical, which is twice as potent in toxicity as ethanol, the alcohol in alcoholic drinks.

In general, the skin is an effective barrier that protects the body from taking in toxic chemicals and other potentially harmful substances in the environment. In fact, drug companies have had to develop fairly elaborate technology to create skin patches that are able to release medicines into the body. However, some chemicals -- such as organophosphate pesticides and camphorated oil -- do penetrate the skin easily and can cause serious toxicity.

When used in large amounts, however, enough rubbing alcohol can seep through the skin to cause harm. Some people mistakenly use rubbing alcohol soaks to bring down high temperatures in children with fever. Besides the danger of skin absorption, this treatment exposes the child to inhalation of alcohol vapors, which get into the bloodstream.

Children who have large amounts of isopropyl alcohol in the blood can experience nausea, vomiting, lethargy and even coma. An average 1-year-old, for example, would develop serious toxic effects from drinking about half a cup of rubbing alcohol.

In summary, wiping or rubbing the skin with small amounts of isopropyl alcohol is safe. Prolonged soaking in large amounts increases the risk of absorption and toxic effects. Above all, don't use rubbing alcohol soaks or sponge baths for children with fever.

For more information or any questions about the toxicity of household or commercial products, call the National Capital Poison Control Center at Georgetown University: 625-3333.

Follow-Up: Dehydration

Q. I am a 27-year-old competitive runner and was interested in your answer about preventing dehydration during exercise. Some of my friends seem to inappropriately limit their fluids and either take just a swallow or two of cold water or merely rinse their mouths with water, rather than drinking as much fluid as they comfortably can.

My coach recommends drinking Gatorade after workouts, and I drink more than a quart a day. It seems to speed recovery and help ward off cramps.

My question: Is there any danger of getting too much potassium this way? Are there any dangers in drinking this much Gatorade? Would taking salt tablets be a better way of replacing lost salt?

A. I agree with your coach -- it's a good idea to replace lost fluids, both before, during and after heavy exercise, especially in the summer heat. Your friends' habit of just rinsing their mouth with cold water may seem macho, but it's not smart.

Gatorade and other "sport drinks" replace water and minerals (mainly salt) that are lost through sweat.

Although plain cool water works well for most people, those who exercise heavily for long periods may benefit from the sugar and salt contained in these beverages.

Gatorade is mostly flavored water, with some sugar and salt (sodium chloride) added. The amount of potassium is small; it would be nearly impossible to get too much. For example, you'd have to drink about a gallon of Gatorade before getting as much potassium as a large banana contains.

Gatorade and other sport drinks supply modest amounts of salt, less than what you could obtain from many other beverages. The concentration of sodium in Gatorade is 20 milliequivalents per liter, compared with the 40 to 60 milliequivalents per liter in the sweat you lose during exercise.

You could make a drink with a similar amount of salt and sugar in it by adding a 1-gram salt tablet and 4 tablespoons of sugar to one quart of water.

Before taking salt tablets, however, people who have heart or kidney problems should check with their doctor. I think either plain water or one of the commercially made sport drinks is a safer way to replace the fluids that are lost during exercise.

Jay Siwek, a family physician from Georgetown University, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington.

Consultation is a health education column and is not a substitute for medical advice from your physician.

Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Questions cannot be answered individually.