Homes and Jobs Make Asthma More Likely
Workplace exposures may account for a fourth of new cases

(HealthDay News) -- The places people live and work can have a major effect on their chances of developing asthma.

A European study found that certain workers are more likely than people in the general population to develop work-related asthma, and a U.S. study found that children who live close to heavily traveled roads are at increased risk for asthma.

The European researchers analyzed information about health and workplace exposure to chemicals and other asthma-causing substances among more than 6,800 people who took part in the European Community Respiratory Health Survey. None of the participants had asthma at the start of the study.

Exposure to workplace substances known to cause asthma increased the risk of asthma over nine years by an average of 60 percent, the study found. The highest risk was among printers (137 percent more likely to develop it than people in other occupations), nurses (122 percent), woodworkers (122 percent), agriculture/forestry (85 percent), and cleaning (71 percent).

The risk of asthma tripled after incidents such as fires or chemical spills, which the researchers said highlights the importance of following up with workers after such events.

Overall, workplace conditions could be responsible for about 25 percent of new asthma cases in industrialized countries, according to the study, which was published in The Lancet .

In the second study, researchers at the University of Southern California Keck School of Medicine found that traffic pollution increases asthma risk in children who are already genetically susceptible to the disease.

Previous research had identified variations in genes that control enzymes responsible for clearing harmful chemicals breathed into the body. These gene variants have also been linked to the development of asthma and other respiratory diseases.

In their study of more than 3,000 asthmatic children, the Keck team analyzed the presence in children of two enzymes that help rid the body of toxins such as vehicle exhaust pollutants: levels of microsomal epoxide hydrolase (EPHX1) and genetic variations in gluathione S-transferase P1 (GSTP1).

Children with very active EPHX1 were 1.5 times more likely to have asthma than were children with low EPHX1 activity, and those with high EPHX1 activity and a variation in the GSTP1 gene were four times more likely to have asthma, the study found.

It also found that exposure to traffic pollution was a major factor in triggering genetic susceptibility to asthma.

Children with very active EPHX1 who lived within 75 meters of a main road were more than three times as likely to have asthma as those with low EPHX1 activity. But children with one or two variations in the GSTP1 gene who lived close to a major road were up to nine times more likely to have asthma than those who lived farther away from a major road.

The study was published in the journal Thorax .

On the Web

The American Lung Association has more about childhood asthma.

SOURCES: HealthDay News ; July 26, 2007, The Lancet ; BMJ Specialist Journals, news release, Aug. 21, 2007
Author: Robert Preidt
Publication Date: Aug. 31, 2008
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