Pool chlorine, parental stress raises kids' allergy risk

As research continues to investigate what causes allergies and why the incidence of allergy is increasing, two studies have recently highlighted factors which have been found to correlate with an increased risk of children developing asthma and allergies.

One study, of 847 Belgian teenagers between the ages of 13 and 18 years, found that those teenagers who spent more than 1,000 hours swimming in chlorinated pools, either indoors or outdoors, had more than eight times the risk of having asthma and allergies than did teens who primarily swam in pools using a copper-silver disinfecting method. An increased risk was found in those who spent more than 100 hours swimming in chlorinated pools, and the risk went up in proportion to exposure.

The study was published in the Sept. 14 online issue of Pediatrics.

A second study, published the July 2009 issue of Proceedings of the National Academy of Sciences, found parental stress increased a child's risk of developing asthma, especially if the child was exposed to traffic pollution or smoking while still in the womb.

Data was collected on 2,497 children living in southern California aged 5 to 9 years. The children had no history of asthma or wheeze when the study started. Over three years, the researchers tracked whether or not the children developed asthma.

In addition, the parents were asked to fill out a questionnaire that measured stress, the children's exposure to traffic-related pollution and whether the children were exposed to tobacco smoke before birth.

By itself, the researchers found stress or socio-economic status did not increase the risk of developing asthma. However, when combined with traffic pollution or exposure to smoking before birth, parental stress increased the risk of asthma more than it did for children exposed to only pollution or smoke.

As exposure to traffic pollution and prenatal smoking as well as stress are more common in lower socioeconomic areas, the researchers believe their findings may help to explain the social disparities in asthma.