Why do more of us have allergies, asthma?
Ten percent of men and 17 percent of women are allergic to nickel, a common component of cellphones and jewelry. (Joe Raedle/Getty Images)
"It's not just that allergies are being reported more or noticed more," he says. "It's real."
Food allergies in children have increased 18 percent in the past decade, according to the Centers for Disease Control.
Experts aren't sure what's causing the increase, but it may be a combination of theories being studied, including:
The hygiene hypothesis: People are being exposed to far fewer microbes (bacteria and viruses that cause disease and infection), so their immune systems have shifted to allergy-fighting. "In developed countries where we have vaccines, antibiotics, clean water, clean houses and smaller families, the immune system doesn't have as much to do when it comes to fighting disease," says McMorris, so it starts producing allergy antibodies to things like cats or dust.
Smaller families: In larger families, older kids bring germs home from school, exposing younger siblings early to microbes. Studies have found that if kids are put into day care their first six months, there's a protective effect against allergies.
Airtight houses: Since the energy crisis of the 1970s, houses and offices have been sealed up much tighter, concentrating stale air and indoor allergens, explains McMorris. On top of that, kids are more sedentary and spending more time indoors exposed to those allergens.
Avoiding vs. consuming "high-risk" foods: One study looked at the rate of peanut allergy among Jewish children in Israel vs. Jewish children in the United Kingdom, where the rate of peanut allergy is 10 times higher. Israeli infants consume peanut in high quantities in the first year of life, while U.K. infants avoid peanuts. "These findings raise the question of whether early introduction of peanut during infancy, rather than avoidance, will prevent the development of peanut allergy," according to a November 2008 study in the Journal of Allergy and Clinical Immunology. The appropriate time for introducing high-risk foods such as peanuts, tree nuts and sesame is still an unanswered question, admits McMorris.
Exposure to traffic: Diesel exhaust particles have been shown in multiple studies to enhance the allergic response. In urban communities, where we live closer to diesel exhaust and traffic, exposure means you're more likely to develop allergies, while those who are already allergic are more likely to have a response.
Unusual sources of allergic reaction
Cellphones and jewelry: Ten percent of men and 17 percent of women are allergic to nickel, a common component of cellphones and jewelry. Red, itchy, scaly and/or thickened skin, especially on the face and neck, are symptoms. Avoid direct contact with nickel-containing products. Use a plastic cover or ear piece for your cell phone and switch to high-carat gold, palladium or platinum jewelry.
Cosmetics: Fragrance and preservatives in cosmetics commonly cause skin redness, itching, crusting, swelling, blistering, dryness and scaling, said Dr. Luz Fonacier, a fellow of the American College of Allergy, Asthma & Immunology. About 22 percent of those tested react to cosmetic chemicals. Get tested to identify them, and switch brands.
Tattoos: Darker dyes and red dyes in particular can cause red, itchy rashes and other allergic skin reactions. Para-Phenylenediamine (PPD), used in temporary henna tattoos and hair dye, frequently causes contact dermatitis, according to the American Academy of Dermatology. Treat your itchy tattoo with topical medication, but if irritation returns, you may need to have it removed.