Phthalates may be asthma trigger

By Helen Albert, Senior medwireNews Reporter

Research suggests that exposure to two phthalates may be a trigger for asthma-related airway inflammation.

"While many factors contribute to childhood asthma, our study shows that exposure to phthalates may play a significant role," said lead investigator Allan Just (Columbia University, New York, USA) in a press statement.

In 244 children aged 5-9 years who had detectable levels of diethyl (DEP) and butylbenzyl (BBzP) phthalates in their urine, higher detectable levels of both phthalates were positively correlated with levels of fractional exhaled nitric oxide (FeNO), an indicator for airway inflammation.

More specifically, log-unit increases in DEP and BBzP increased levels of FeNO by 6.6% and 8.7%, respectively, following adjustment for other phthalate metabolites and potential confounders. The presence of wheeze appeared to strengthen the association between BBzP level, but not DEP level, and FeNO.

"Many asthma patients only have asthma exacerbations a few times a year, making it difficult to discern short-term associations between environmental exposures and the disease," explained co-author of the American Journal of Respiratory and Critical Care Medicine article and fellow Columbia University researcher Matthew Perzanowski.

"To solve this problem, we used nitric oxide, which has been shown to be a reliable marker of airway inflammation in response to known asthma triggers like vehicle emissions."

Metabolites of two other phthalates, di(2-ethylhexyl) and di-n-butyl phthalate, were not associated with FeNO levels, notes the team. In addition, no significant association with seroatopy was observed.

Just and co-authors previously reported a link between phthalate exposure and early eczema. Exposure to the chemicals, which are used in the production of plastics and personal care products, has also been associated with endocrine disruption, and adverse neurobehavioral and reproductive effects.

"These findings suggest a role for ubiquitous exposure on airway inflammation in a susceptible population," write Just et al.

"Future studies can prospectively follow these children to observe whether associations persist through childhood and the long-term consequences to respiratory health of increased inflammation in children," they conclude.

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