Children who attend school near concentrated animal feeding operations may be at a higher risk for asthma, according to a new Iowa study. However, the researchers cautioned that more research is needed.

"Previous research has shown increased rates of asthma among children living in rural areas of Iowa and the United States," says Joel Kline, lead researcher and professor of internal medicine at the University of Iowa. This study was specifically designed to look at children attending a school close to a CAFO compared to those who did not.

Researchers surveyed the parents of kindergarten through fifth-grade students attending two Iowa elementary schools to compare the prevalence of asthma among students. The “study” school is located a half-mile from a CAFO in northeast Iowa; the "control" school is in east-central Iowa, more than 10 miles away from any CAFO. Sixty-one participants responded to the study school, and 248 participants responded from the control school.

Study results indicate a significant difference in the prevalence of physician-diagnosed asthma between the two schools: 12 children (19.7 percent) from the study school located near a CAFO and 18 children (7.3 percent) from the control school. The overall rate of physician-diagnosed asthma reported for Iowa is about 6.7 percent.

Using the broadest definition of asthma (physician diagnosis, asthma-like symptoms or asthma medication use) the prevalence rate was 24.6 percent at the study school, compared to 11.7 percent at the control school.

Although results also showed that children in the study school located near a CAFO were more likely to have a parent who smoked, which is also a risk factor for asthma. The significance of parental smoking diminished when analyzed with other variables such as pet ownership, age and residence in a rural area or on a farm.

Kline stressed caution in the study results. "Since different physicians were diagnosing asthma among the two groups, it's possible that one group may have been more or less likely to receive an asthma diagnosis for similar symptoms," he says.

 You can find the study online at, Science Daily