WASHINGTON — A person's susceptibility to allergies appears related to age, income, education, race and place of residence, but researchers don't know why.
Dr. Paul C. Turkeltaub, of the Food and Drug Administration, said the surprising associations between response to standard allergy tests and demographic factors appeared in data from a large national health survey.
In the survey, more than 14,000 randomly selected healthy volunteers were given skin tests to determine whether they were allergic to house dust, mold spores, cat and dog hair, and pollen from ragweed, oaks and grasses.
Turkeltaub outlined the findings at a recent seminar and said 20% of those tested developed a small red patch on their arms, showing a sensitivity to at least one of the substances scratched under their skin.
Reactions to skin tests are linked to such other allergic reactions as runny nose, watery eyes, asthma and hives, Turkeltaub said.
50 Million People
Dr. Raymond Slavin, director of allergy and immunology at the St. Louis University School of Medicine, estimated last spring that 50 million people in the United States are allergic to something and that treating the ailments costs more than $1.5 billion annually in hospital and doctors' fees.
Slightly more men than women were sensitive to at least one allergen and slightly more blacks were sensitive than whites. He said 23% of blacks showed reactions, compared to 19.5% of whites, but not enough blacks were studied to make the results statistically reliable.
People between 18 and 24 were most sensitive to the allergens, with one-third of males in this age group showing at least one reaction. Older and younger people showed fewer reactions.
People with higher incomes and more education were more likely to show reactions, and urban dwellers were more reactive than rural residents, he said. People in the northeast were much more sensitive than those in the South.
Turkeltaub said the results mean some socioeconomic factors are involved in the development of allergies, but experts do not know how. He said the breezes from the Gulf of Mexico and low pollen exposure may account for the lower sensitivity of Southerners.
The allergen that triggered the most reactions was ragweed and rye grass pollen, with 10% of the population showing sensitivity to these hay-fever agents. Slightly more than 2% of those tested were sensitive to dog and cat hair and about 6% reacted to house dust.
Turkeltaub said it is not known if people with highly sensitive immune systems and reactivity to allergens have longer or shorter lives than those who are less sensitive. He said some evidence shows that reactive people may have stronger defenses against some diseases, but may have a greater chance of getting heart disease along with health problems from allergies.