More than 50 percent of the U.S. population tested positive to one or more allergens, according to a large national study. The new findings, based on data from the third National Health and Nutrition Examination Survey (NHANES III) conducted from 1988-1994, show that 54.3 percent of people age 6 to 59 years old had a positive skin test response to at least one of the 10 allergens tested. This is double the rate from 30 years ago.
The highest prevalence rates were for dust mite, rye, ragweed, and cockroaches, with about 25 percent of the population testing positive to each. Peanut allergy had the least prevalence of the substances tested, with nine percent of the population reacting positively to that food allergen.
The findings, published in the Journal of Allergy and Clinical Immunology, were conducted by researchers at the National Institute of Environmental Health Sciences (NIEHS) and the National Institute of Allergy and Infectious Diseases, both institutes of the National Institutes of Health.
A Positive Skin Test Means...
A positive skin test result means that an individual might be more vulnerable to asthma, hay fever, and eczema. "Asthma is one of the world's most significant chronic health conditions," said David A. Schwartz, MD, the NIEHS Director. "Understanding what may account for the rising worldwide asthma rates will allow us to develop more effective prevention and treatment approaches."
NHANES III was a nationally representative survey conducted by the Centers for Disease Control and Prevention to determine the health and nutritional status of the U.S. population. Approximately 10,500 individuals participated in the skin testing. During these tests, skin was exposed to allergy-causing substances (allergens). A positive test was determined by the size of the reaction on the skin. The 10 allergens tested were dust mites, German cockroach, cat, perennial rye, short ragweed, Bermuda grass, Russian thistle, White oak, Alternia alternata, and peanuts.
Researchers also compared skin test responses between NHANES III and the previous survey, NHANES II, conducted from 1976-1980. The prevalence of a positive skin test response was much higher in NHANES III than in NHANES II.
According to the lead author, Samuel J. Arbes, Ph.D. of NIEHS, "An increase in prevalence is consistent with reports from other countries and coincides with an increase in asthma cases during that time." In the United States, the prevalence of asthma increased 73.9 percent from 1980 to 1996. However, Dr. Arbes was quick to point out that differences in skin test procedures between the two surveys prevent them from definitively concluding that the prevalence of positive skin tests has increased in the United States.
"There is still much we don't understand about why some people become sensitized to allergens and why others do not," said Darryl C. Zeldin, MD, senior author on the paper. "Much more research is needed before we can understand the complex relationships between exposures to allergens, the development of allergic sensitization, and the onset and exacerbation of allergic diseases such as asthma."
For more information about allergens and other environmental health topics, visit the websites of the National Institute of Environmental Health Sciences (NIEHS website) or the National Institute of Allergy and Infectious Diseases (NIAID website). |
