Dermatologists are warning consumers that harmless-looking henna tattoos commonly sold at fairs, malls and vacation hot spots may contain a harmful chemical that makes them darker and longer lasting.

The chemical is para-phenylenediamine or PPD, which Dr. Sharon Jacob, an assistant clinical professor of pediatrics and dermatology at the University of California, San Diego, says has been linked to allergic skin reactions, notably in children.

Natural henna tattoos are derived from the leaves of the Lawsonia inermis plant and appear in shades of brown, green and red. Such tattoos last only a few days and are considered harmless.

But some tattoo purveyors add PPD to the henna formula to increase the intensity of the color and its longevity. PPD, which is used in hair dye, turns the tattoo black.

Jacob said hundreds of cases of allergic reactions from PPD henna tattoos have been reported. Reactions range from mild eczema to blistering and permanent scarring. The first sign of a skin reaction is typically redness and itching.

Some people are immediately sensitive to PPD and display symptoms after the first tattoo. Others require multiple exposures before developing an allergy. Jacob advised avoiding all questionable henna tattoos.

"Unless the artist can tell you exactly what's in the tattoo, don't get one," she said.

BODY OF KNOWLEDGE

Blood flows through the filtering kidneys at a rate of 3 pints per minute. The kidneys filter all of the body's blood every 10 minutes. The kidneys are great recyclers, generating only 3 pints of wastewater (urine) for every 4,400 pints of blood filtered.

GET ME THAT. STAT!

Newborn circumcision rates have declined dramatically in the English-speaking world over the last 50 years. For example, the rate in New Zealand dropped to 1 percent in 1995 from 95 percent in 1945.

The exception is the United States. In 1942, the circumcision rate was 64 percent of newborns. In 2005, it was 57 percent.

NEVER SAY DIET

The world's speed-eating record for mixed foods is held by Juliet Lee, who consumed seven chicken wings, 1 pound of nachos, three hot dogs, two personal pizzas and three Italian ices in seven minutes.

NUMBER CRUNCHER

A slice of Cold Stone Creamery's "a cheesecake named desire" (145 grams) contains 410 calories, 171 from fat. That's 29 percent of the recommended total fat intake for a 2,000-calorie daily diet.

It also contains 50 milligrams of cholesterol (17 percent); 250 mg of sodium (10 percent); 57 grams of total carbohydrates (19 percent); 38 grams of sugar and 4 grams of protein.

MEDTRONICA

Spine-health

Spine-health.com

A very comprehensive site for information on back pain, degenerative disc disease, sciatica, spinal stenosis and more. There are also sections on helpful exercises, finding a good mattress and a message board.

STORIES FOR THE WAITING ROOM

Between 1766 and 1910, nostalgia was cited on death certificates as a cause of death. Specifically, 31,987 Americans officially died from missing their loved ones, home or prolonged overwhelming melancholy during this time period.

PHOBIA OF THE WEEK

Ephebiphobia — fear of teenagers

BEST MEDICINE

A doctor was examining an elderly patient who was hard of hearing. Placing his stethoscope on her chest, he said, "Big breaths."

"Yes," the woman replied. "They used to be bigger."

OBSERVATION

A person seldom falls sick, but the bystanders are animated with the faint hope that he will die.

— American essayist Ralph Waldo Emerson (1803-1882)

LAST WORDS

Go on, get out. Last words are for fools who haven't said enough.

— Revolutionary Karl Marx (1818-1883) to his housekeeper, who urged him to tell her his last words so she could write them down for posterity

To find out more about Scott Lafee and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

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