Hope you're ready to commit to the "temporary" tattoo you got at the beach on spring break. Some shops advertising "henna" tattoos actually use something called black henna, which may contain a chemical used in hair dye that can cause some dramatic skin reactions, the U.S. Food and Drug Administration advises consumers in a post published today.

The FDA has received consumer reports of some long-lasting skin reactions after a black henna tattoo, including redness, blisters, "raised red weeping lesions" (yikes), loss of pigmentation, increased sensitivity to sunlight, and in some cases, permanent scarring. Your skin freak-out may happen right after the tattoo is applied, or up to two or three weeks later. 

The photos of reactions to the black henna can be striking. The FDA post shows an image of a group of friends showing off their temporary tattoos - the littlest hand in the group is that of a 5-year-old girl, whose skin severely reddened where the tattoo was applied. And in 2008, we wrote about a New England Journal of Medicine case study describing a 19-year-old woman whose skin bubbled up over the swirly tattoo pattern after she got a black henna tattoo at a wedding. 

FDA

A group of friends compare their temporary tattoos. The smallest hand (top right) belongs to a five-year-old who developed severe reddening where the tattoo was placed.

FDA

A 5-year-old developed severe reddening where the tattoo was placed.

Black henna, it's important to note, is not actually henna, or at least not entirely. Traditional henna is reddish-brown in color, and is made from a flowering plant of the same name that grows in tropical and subtropical regions in Africa, southern Asia and parts of northern Australia. Real henna has been used for centuries to dye skin, hair or fingernails. 

"The main difference between regular henna and 'black' henna is that a mix of other ingredients with henna is used to darken the color of the temporary tattoo," said FDA spokeswoman Tamara Ward in an email. "Ingredients may include coal-tar hair dye containing p-phenylenediamine (PPD), an ingredient that can cause dangerous skin reactions in some people." 

"You may see 'black henna' used in places such as temporary tattoo kiosks at beaches, boardwalks, and other holiday destinations, as well as in some ethnic or specialty shops," Ward says. "Depending on where you are, though, it's possible no one is checking to make sure the artist is following safe practices or even knows what may be harmful to consumers." That's because not all states have laws or regulations overseeing temporary tattoos.

One way to spot a shop that uses black henna: Adding the PPD makes the tattoo darker and longer-lasting. A real henna tattoo, on the other hand, fades to brown on the skin as it dries, and it will only last a few days -- so be wary of a shop that advertises tattoos that last longer than that. 

Related: 

Henna hazard: Chemical causes ornate allergies

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Reuters

Members of the Detroit Derby Girls Travel Team battle The Chicago Outfit Syndicate during a women's flat track roller derby bout in Detroit, Michigan, in April 2011.

The women of roller derby are always crashing and smashing into each other, constantly trading bumps and bruises -- and at the same time, they're also trading the microscopic bugs living on their skin. That's according to a new study that used derby to investigate the way contact sports can mix up our skin microbiome. 

"As a derby skater, I was always curious about the unseen ways my teammates influenced me," says Jessica Green, the director of the University of Oregon's Biology and the Built Environment Center, who co-authored the new paper, published online today in the new journal PeerJ. Green is also a former jammer - that's the skater who scores the points - with the Emerald City Roller Girls of Eugene, Ore. (Her derby name: "Thumper Biscuit," she says.) 

"When I was on the track learning a new move - like 'jumping the apex' - my mind would drift to science and 'microbiome land,'" Green says. "I realized that contact sports are an ideal venue to explore if and how touching mediates the exchange of microbes among people in a group setting." 

We know, even if we don't always like to remember it, that our skin is teeming with thousands of kinds of bacteria, and we also know that those microbial communities protect us from pathogens and help regulate our immune systems. But Green and her fellow researchers at the University of Oregon wanted to know more about where we get those microbes, and how those invisible bacterial communities are changed and distributed every time we touch each other.

"For years, most of what we knew about the skin microbiome came from medical studies targeting important pathogens dispersed between sick people and health care staff in a hospital setting," explains lead author James Meadow, a postdoctoral research associate at the University of Oregon's Biology and the Built Environment Center. "This study enabled us to look at whole communities of microbes being passed between healthy people." 

And roller derby -- where players jockey for track position by bumping upper arms, hips or, ah, "booty" (seriously, that's the official roller derby nomenclature) -- seemed like an ideal contact sport to study to find out.

"Over the years I've noticed it's hard to get folks interested in microbes. Maybe it's because you can't see microbes with the naked eye and they are also are misunderstood as being gross," says Green, whose derby past helped with planning the logistics for co-author Keith Herkert, who did the project for his undergraduate honor's project. "Adding roller derby into the mix makes microbes a lot more appealing."

Women from the Emerald City Roller Girls of Eugene, Ore.; the D.C. Roller Girls of Washington, D.C.; and the Silicon Valley Roller Girls of San Jose, Calif., participated in the study, and all skin samples were collected at the Big O Tournament in Eugene on Feb. 10, 2012. All the women were swabbed in the same small area of their upper arm, one area of the skin that is exposed and frequently bumped during a match, or "bout."

After a DNA analysis, the researchers found that teams had similar, distinct microbial communities. "For example, if we had picked a player out at random before they skated in the tournament, I probably could have told you what team she played on," Meadow says. The samples for the D.C. team, for example, contained Brevibacterim, and the samples from the Oregon skaters were similar to the surface samples taken from their home track. But after the teams competed, the hour-long bout mixed up their microbes, leaving opposing teams with more similar-looking microbial communities, the analysis found. Specifically, six different kinds of bacteria - Strepococcus, Sphingomonas, Eubacterium, Porphyromonas, Aerococcus and Methylobacterium - were shared by competing teams after, but not before, the bout.

Next, Meadow and his fellow researchers want to understand how long those similarities last, and how sharing our microbes influences our health in the long term. 

As Green explains it, using roller derby is an easier-to-follow example of how we literally influence each other on a microbial level.  "The people we choose to be in community with -- through sports, work, and social circles -- likely influence our personal biome in ways we never imagined," Green says. 

"Our bodies are home to countless microbes that help define who we are," she continues. "Our health and well-being depend on our microbes. People that have the right cocktail of microbes on their skin, for example, are better positioned to fight off germs or pathogens, because their good microbes out-compete the bad invaders. We currently know very little about where our personal microbial communities come from. Our study suggests that our microbes come, in part, from the people we touch. "

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Summit Medical Group

In this image provided by Summit Medical Group, an unidentified man shows off his case of pityriasis rosea, which often appears in the shape of a Christmas tree.

It may start with a sore throat. After that, there's the aptly-named "herald" patch, a round or oval pink patch that usually shows up on the chest or abdomen, then fades. Days or weeks later, the pink dots start. Sometimes they're on the front, sometimes the back.

And what's really weird is their pattern.

"It was like a tattoo that covered my back in the shape of a Christmas tree," says Mark Jared Zufelt, a 41-year-old Seattle writer/director/photographer, who came down with the rash in his 20s. "It fanned out from the top and worked its way down. It was gross." Zufelt doesn't have a photo of his strange skin condition, but Summit Medical Group has a great example of what the condition, officially called pityriasis rosea, looks like.  

Despite its name, the Christmas tree rash has nothing to do with Christmas trees or even the holiday season. In fact, it usually shows up in the spring and fall, according to Dr. Kenneth Beer, a Palm Beach, Fla., dermatologist.

"Nobody really knows why people get it but a lot of the time, it follows a sore throat or upper respiratory tract infection," he says. Doctors believe the condition is caused by a virus, and it's not thought to be contagious. 

Itchy and scaly (each pink dot is covered with a thin white scale, like cigarette paper), the rash is fairly common and sometimes confused with ringworm, eczema or psoriasis. Beer says he sees about a dozen cases of Christmas tree rash a year, usually in people under the age of 40.

Ironically, his teenage son came down with the worst case he's ever seen.

Dermatlas at Johns Hopkins Medicine

This image provided by Dermatlas at Johns Hopkins Medicine, shows another view of pityriasis rosea.

"He was bright red and had it everywhere -- his chest, abdomen, back, arms, legs," says Beer. "He was miserable."

Treatment for the rash usually involves topical steroids and antibiotics.

"We'll put some people on oral medications but we usually just do topicals," he says. "But the other thing that helps is a little bit of sun or ultraviolet light, UVB. People can go outside and get 15-20 minutes of sun a day or go to their dermatologist's office and use their light boxes." Tanning beds, which primarily give off UVA rays, won't help, he says.

The rash, which Beer terms "uncomfortable but not horrible" usually goes away within two to four weeks with treatment. In addition to topical steroids, oatmeal baths can help alleviate the itching.

While pityriasis rosea has no connection to actual Christmas trees, holiday greenery isn't completely blameless when it comes to allergic reactions.

In 2007, a British teacher named Nicola Coleman made headlines when she broke out in red hives shortly after putting up a Norway spruce. Researchers have also found that some people are allergic to the mold found in pine or fir trees. They've dubbed this allergy -- which triggers a runny nose, sneezing and asthma attacks -- Christmas tree syndrome.

"You can also have contact dermatitis allergies to the sap in some of the trees," says Beer. "But that's totally different."

Zufelt says he doesn't remember what time of year it was when he broke out with his Christmas tree rash, but remembers that it definitely wasn't December.

"I know it wasn't Christmas because that would have been too serendipitous," he says. "It would have made the Christmas card had that been the case."

Related:

Do you hear what I hear? Your brain on Christmas music

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Stas Volik /Featurepics.com

Stress and a lack of sleep can cause a lack of melanin, causing that haggard, jaundiced look.

It’s almost midnight and you’re stuck in a tangle of wrapping paper and ribbon while cookies burn in the oven. You're exhausted but your holiday to-do list keeps you up and working.

After a few hours of fitful sleep, you stumble into the bathroom and gaze in the mirror. Your skin is sallow and the bags under your eyes make you look as if you went five rounds with a prizefighter.

What is it about lack of sleep and stress that makes us look so ragged?

“Stress causes a drop in the skin’s ability to protect itself,” explains Dr. Amit Sood, associate professor of medicine and chair of the Mind Body Initiative at Mayo Clinic. “All of this happens with chronic stress -- if you do not have healthy collagen in your skin, you would have baggy sort of skin under your eyes.”

And stress can also lead to less melanin, causing that jaundiced, haggard look. Melanin pigments the skin, giving humans their complexion.

According to Sood, author of Train Your Brain, Engage Your Heart, Transform Your Life: A Course in Attention and Interpretation Therapy, we're at war with ourselves whenever we're stressed.

“You lose efficiency; your sleep is not as restful; you eat more, you gain weight; your relationships are affected,” he says.

As a result, our faces look, well, uglier. And puffier. But where does the puff come from?

Dark circles and bags appear when the body is unable to rejuvenate at night due to lack of sleep, says anesthesiologist, internist and bestselling author Dr. Michael Roizen, who compares puffy eyes to swollen ankles.

As we go through the day, we sometimes accumulate water in our bodies instead of passing it (as urine). The excessive water pools beneath the eyes, giving those telltale dark, puffy circles. If we don’t get enough sleep -- on our backs or sides -- our skin does not have the chance to refresh itself and tighten up.

"Normally when you sleep, you distribute water in the body," says Roizen, chair of the Wellness Institute at the Cleveland Clinic. Not sleeping causes us to accumulate water under our eyes, giving us that extra "baggage".

Roizen agrees with Sood that experiencing a lot of stress leads to lack of sleep -- and this can become a dangerous cycle. But stress does more than make people look weird.   

“What you get from stress is the wrinkles of aging,” says Roizen, who co-authored several bestsellers with Dr. Mehmet Oz, including YOU: Being Beautiful: The Owner’s Manual to Inner and Outer Beauty. “Stress causes you to age.”

Roizen also notes that stress not only causes wrinkles on the face but wrinkles in your arteries, as well, which can cause serious problems at an earlier age.

And the aging effect doesn't stop there.

“Your cells are biologically 10 to 15 years older … if you are chronically stressed," says Sood. "If you are 45, the cells signal as if they are 60 years old."

Both believe that reducing stress can enhance physical appearance and improve health.

“Stress and joy are two sides of the same coin,” advises Sood. “Engage with life and find meaning in it.” 

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Sunburns readily advertise that we've had fun in the sun, and perhaps have been a bit careless, but what exactly goes on in our cells to produce the painful, red inflammation has not been clear.

Now, researchers have discovered a molecular signal that triggers sunburns.

When our skin cells are exposed to ultraviolet B (UVB) radiation , a specific form of RNA, called micro-RNA, is damaged, the study found. (RNA is similar in structure to DNA, which makes up our genes.)

This damaged RNA is then released as a signal of solar injury, and prompts neighboring, healthy cells to stimulate the production of factors that promote inflammation, the researchers said.

The entire process is intended to remove sun-damaged cells, which could turn cancerous if not cleared away.

"The cells of our skin can sense dead, [sun-damaged] cells, because the cells release damaged RNA," said study researcher Dr. Richard Gallo, professor of medicine at University of California, San Diego School of Medicine.

While other factors likely play a role in the inflammatory process we see as a sunburn, the findings suggest the damaged RNA molecules serve as a marker for radiation-caused injury, the researchers said. 

 Why Sunburns Hurt ]

The findings may have implications for medical conditions, the researchers said.

For example, one treatment for the skin condition psoriasis is exposure to UV light. But while the light can relieve symptoms, it also increases skin cancer risk, Gallo said. The new findings suggest that certain RNA molecules could be used in place of UV therapy, and produce the same benefit, Gallo said.

In addition, people with certain autoimmune conditions get a burning sensation with very little exposure to UV light, before unhealthy cell damage has occurred, Gallo said. Blocking the micro-RNA pathway may be a way to reduce inflammation in these patients, Gallo said.

However, healthy people without such conditions would not want to block this pathway just to prevent sunburn, because it is an important way for the body to heal and get rid of damaged cells, Gallo said.

"The inflammatory response is a normal part of our protection against the sun," Gallo said.

The study is published online today (July 8) in the journal Nature Medicine.

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• Infographic: What to Look for on New Sunscreen Labels
• 4 Common Skin Woes, and How to Fix Them
• 8 Strange Signs You're Having an Allergic Reaction

More from The Body Odd:

• Smelly foods make you eat less
• Trick yourself into eating veggies
• Why the urge to pee ruins sleep 

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American Journal of Human Genetics

Look, ma, no fingerprints!

The upside of adermatoglyphia: You may have a bright future in crime.

The rare skin condition causes some people to be born without fingerprints, and it’s the subject of a new study published in the American Journal of Human Genetics. The report explores the underlying cause of the condition and underscores the usefulness of rare genetic mutations as a tool for investigating unknown aspects of biology. 

Adermatoglyphia “is apparently exceedingly rare, although it may be under-diagnosed due to the fact it does not affect, significantly, the health status of the patients,” explains senior study author, Dr. Eli Sprecher from Tel Aviv Sourasky Medical Center in Israel.

Human skin has ridges, called dermatoglyphs, that are present on the fingers, palms, toes and the soles of our feet. The dermatoglyphs on the finger tips are better known as fingerprints.

You may not know it, but fingerprints help us perceive fine sensations at the tips of our fingers. You’re probably more familiar with the “CSI” aspect of finger prints, their importance in establishing identity. In some circles, adermatoglyphia has been nicknamed "immigration delay disease" since affected individuals report difficulties entering countries that require fingerprint recording.

To better understand the genetics of fingerprint formation, Dr. Sprecher and his colleagues studied a large Swiss family with adermatoglyphia. Affected members of the family had displayed an absence of fingerprints since birth and, according to the study, this absence was associated with a reduced number of sweat glands.

Researchers pinpointed a mutation in the gene SMARCAD1 as the root cause. The protein encoded by the gene is thought to control the expression of a large number of target genes associated with development. More specifically, the group demonstrated the existence of a short version of SMARCAD1 that was exclusively expressed in the skin and was mutated in individuals with the disease.

"Taken together, our findings implicate a skin-specific version of SMARCAD1 in the regulation of fingerprint development," concludes Dr. Sprecher, who goes on to say SMARCAD1 may target genes involved in both fingerprint and sweat gland development. He continues, "Further, as abnormal fingerprints are known to sometimes herald severe disorders, our finding may also impact the understanding of additional diseases affecting not only the skin."

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