Research carried out at the University of Southern California, Los Angeles suggests that the combination of genetic susceptibility and traffic fumes increases the risk of asthma.

The researchers looked at microsomal epoxide hydrolase (EPHX1) levels and genetic variations in glutathione S-transferase P1 (GSTP1) in over 3,000 children who suffered from asthma. EPHX1 and GSTP1 play a significant role in ridding the body of toxins, including vehicle emissions (polyaromatic hydrocarbon).

The children with very active EPHX1 were found to be 1.5 times more likely to suffer from asthma, compared to those with low EPHX1 activity. Children with high EPHX1 levels who also had a GSTP1 gene variation were four times more likely to suffer from asthma.

The proximity of the road traffic was a major factor so that, compared to a child with relatively low EPHX1 levels, a child with a very active EPHX1 living within 75 metres of a busy road is more than three times as likely to have asthma. A child with one or two GSTP1 gene variations who lives near a busy road is up to nine times more likely to have asthma than a child who does not.

Whether a child's asthma was current, had started early or later on in life did not seem to be relevant.

‘Microsomal epoxide hydrolase, glutathione S-transferase P1traffic and childhood asthma’ Online First Thorax 2007; doi: 10.1136/thx.2007.080127

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First Published December 2007

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