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12-07-2011 | General practice | Article

Psychosocial stress linked to air pollution lung susceptibility in children

Abstract

Free abstract

MedWire News: Psychosocial stress may increase lung susceptibility to the detrimental effects of traffic-related air pollution (TRP) in children, suggest US study findings.

"This is the first study demonstrating that growing up in a stressful household was associated with larger traffic pollution-induced lung deficits in healthy children compared to low-stress households," said lead study author Talat Islam (Keck School of Medicine, Los Angeles, California).

He added: "One possible explanation for the stress-related pattern of TRP respiratory effects is the biological pathways common to the effects of TRP and stress. Like air pollution, stress has been linked to both inflammation and oxidative damage at the cellular level, so this may explain the association."

For the study, Islam and team administered the Perceived Stress Scale (PSS) to parents of 1399 children aged, on average, 11.2 years who participated in the USC Children's Health Study in Southern California. Children were assessed for lung function and other respiratory health outcomes.

Exposure to TRP was calculated by estimating exposure to nitric oxide (NO), nitrogen dioxide (NO2), and total oxides of nitrogen (NOX) at school and at home.

PSS values ranged from 0 to 16, with a mean score of 3.9. Less than 25% of parents reported PSS scores below 2 (23%) or higher than 7 (20%). High parental PSS varied according to sociodemographic and personal factors, with Asian and Hispanic households 2.67- and 1.52-fold more likely to show higher levels of PSS than White and non-Hispanic households, respectively.

Furthermore, higher household stress was associated with markers of social deprivation such as low socioeconomic status, lack of health insurance, and housing characteristics such as second-hand smoke exposures, cockroaches in the home, and lack of air conditioning.

"These children may be a group at particularly high risk of preventable TRP-associated deficits in lung function," say the researchers.

No significant associations were seen between parental stress alone and lung function levels in children. However, lung function decreased as levels of TRP increased among children in high-stress, but not in low-stress, households.

Among children from high-stress households (parental PSS>4), deficits in forced expiratory volume (FEV1) of 4.5% and of 2.8% were associated with each 21.8 parts per billion increase in NOX at homes and schools, respectively.

Similar findings were observed when the analysis was restricted to non-asthmatic children.

Lastly, the team found that the magnitude of TRP-associated deficits in FEV sub>1 and forced vital capacity (FVC) levels in children growing up in high-stress households was larger than deficits reported for children exposed to maternal smoking during pregnancy and second-hand smoke.

The findings are published in the American Journal of Respiratory and Critical Care Medicine.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Ingrid Grasmo

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