Experts Link Dust Mites and Asthma

The Institute of Medicine on Wednesday concluded what many have long assumed: that the ubiquitous dust mite--found in virtually every household in America--can lead to the development of asthma in susceptible people and that it and other common indoor substances can worsen symptoms in those who already have the disease.

An institute panel of experts examined all the scientific data available in an attempt to better understand a worsening health situation that has produced a 75% increase in asthma since 1980, especially among African American children and those living in poor neighborhoods.

The committee conducted no new research of its own, instead making a comprehensive examination of existing research. But the study failed to solve the mystery of why asthma has been increasing so dramatically in recent years and why some individuals are more likely than others to develop the disease, which can be life-threatening.

While indoor allergens contribute to the ailment, there are almost certainly other factors involved, the panel said.

“We don’t understand why asthma is rising in all populations,” said Dr. Diane Gold, assistant professor of medicine in Harvard Medical School’s department of environmental health.

Gold, who served on the panel, said that “we think a larger proportion of the population has become vulnerable or sensitive. The question still is why.”

Theories abound, among them: changes in the environment that interact with a genetic predisposition; stress; less exposure to bacteria and other organisms in early childhood, which could prime the immune system, rendering people less vulnerable to asthma; and Americans’ growing sedentary lifestyle and lack of exercise.

In the absence of answers, panel members urged that research in those areas continue and that steps be taken to remove or control indoor pollutants.

While they singled out dust mites as a factor in developing the disease, they also pointed the finger at other culprits--including cats, cockroaches and environmental tobacco smoke--as exacerbating symptoms in those already afflicted.

An estimated 17.3 million Americans suffer from asthma, according to the federal Centers for Disease Control and Prevention. More than 80% of the cases develop in early childhood.

It is the most common chronic illness among American children and one of the most chronic ailments overall in the country--the seventh most common, according to the American Lung Assn. The disease leaves its victims coughing, wheezing and gasping for air.

The report was requested by the Environmental Protection Agency’s indoor air quality office, which has no regulatory authority, in response to an announcement in January 1999 by First Lady Hillary Rodham Clinton that the administration would seek to increase education about indoor asthma “triggers” and promote school-based programs to teach children how to manage the disease.

Experts predicted that the report will strengthen these efforts, particularly for funding of indoor pollution controls and education programs.