Kids in farming environment less prone to asthma

23 October, 2007

Children living in a farming environment seem to have a lower risk of asthma than their urban counterparts or even those living in a non-agricultural rural environment.

A study conducted by the University of Alberta, Canada – as a part of the analysis of two surveys involving 13,524 asthma-free children aged less than 12 years in the ongoing Canadian National Longitudinal Survey of Children and Youth (NLSCY) – showed that children living in a farming environment had a lower risk of developing asthma than their counterparts who resided in either non-farming rural environments or an urban environment.

The two-year, cumulative incidence of asthma was only 2.3% in farm children, compared to 5.3% for other rural, and 5.7% for urban children.

William Midodzi, of the Department of Public Health Sciences in the University of Alberta School of Public Health in Edmonton, Canada, and the lead author of the study, said: “Farm children of ages 1 to 5 years also showed a stronger protective effect against asthma than those aged 6 to 11 years, possibly due to earlier exposure to the farm environment.”

Also, while youngsters with parental history of asthma living in farming environments had a reduced risk of asthma compared to children living in rural non-farm environments, children with parental history of asthma living in urban areas had a higher risk when compared with children living in rural non-farm environments.

William Midodzi’s conjecture is that exposure to compounds called ‘endotoxins’ from animal viruses and manure and avoidance of urban environment early in life might have reduced the risk for development of asthma.

The new finding that living in a farming environment reduces the risk of developing asthma is contrary to previous studies reporting that existence of asthma was related to exposure to farming environments.

The Canadian researchers believe that exposure to endotoxins stimulates the body’s immune system and keeps it busy fighting bacteria, thus reducing the risk of the body turning its immune attention to lung inflammation that causes asthma.

In the opinion of the researchers, clinicians who treat patients with asthma can use these findings to identify high-risk children and also educate parents. They added: “This research suggests that we should discourage childhood exposure to tobacco smoke, encourage breast-feeding, and not worry about keeping children’s environment too sterile.”

The study has been published in the journal Respirology.