Study supports traffic pollution link to allergic disorders in childhood
MedWire News: Results of a Japanese study support a link between pre- and/or post-natal exposure to traffic-related air pollution and the development of allergic disorders in childhood.
Writing in the journal Pediatric Allergy and Immunology, Yoshihiro Miyake (Fukuoka University) and colleagues explain: “There is evidence that air pollution from traffic may exacerbate pre-existing asthma. However, the role of traffic-related air pollution in the initiation of allergic disorders in children is still not clearly understood.”
To investigate the relationship between exposure to traffic-related air pollution during pregnancy and in the early years of life and the risk for allergic diseases in children, the team studied 756 mother–child pairs in Osaka.
The distance of each participants’ home from the nearest main road was used as an indicator of exposure to traffic pollution.
The mothers were interviewed during pregnancy and between 2 and 9 months postpartum to identify any changes in living circumstances and potential confounding factors, such as family history of allergic diseases, maternal age, smoking, and home environment.
They were also interviewed between 16 and 24 months postpartum about the development of allergic disorders in their children.
Based on symptom criteria from the International Study of Asthma and Allergies in Childhood (ISAAC), 22.1% and 18.7% of infants had developed wheeze and atopic eczema, respectively, by the third survey. Furthermore, 4.4% and 8.9% of children had been diagnosed with asthma and atopic eczema by this time.
Analysis revealed that living within 50 m of a main road during pregnancy was associated with a 4.01 fold increased risk for doctor-diagnosed asthma and a 2.26 fold increased risk for doctor-diagnosed atopic eczema in children, compared with living at least 200 m from a main road.
However, the team found no significant relationship between proximity to a main road during pregnancy and the risk for wheeze or atopic eczema based on the ISAAC criteria.
The researchers note that it was difficult to distinguish between the effects of the pre- and post-natal exposure because most participants lived at the same address before and after childbirth.
Miyake and team conclude: “The current prospective study found that a shorter distance from the residence during pregnancy to the nearest main road, especially within 50 m, was significantly related to an increased risk for doctor-diagnosed asthma and atopic eczema, but not symptoms of wheeze or atopic eczema, during the first 16–24 months of life in the offspring.”
They add: “Further investigations are needed to determine which specific pollutants increase the risk of allergic disorders at older ages, separating exposures during pregnancy from those after birth.”
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By Mark Cowen