Effects of Woodsmoke Exposure on Airway Inflammation in Rural Guatemalan Women

Michael J Guarnieri,Colin Solomon,John R Balmes,Daniel Pope,Nigel Bruce,Anaite Diaz,Kirk R Smith,Chandreyi Basu,Janet V Diaz,Tone Smith-Sivertsen,John Mccracken,Qinghua Sun

doi:10.1371/journal.pone.0088455

Abstract

BackgroundMore than two-fifths of the world’s population uses solid fuels, mostly biomass, for cooking. The resulting biomass smoke exposure is a major cause of chronic obstructive pulmonary disease (COPD) among women in developing countries.ObjectiveTo assess whether lower woodsmoke exposure from use of a stove with a chimney, compared to open fires, is associated with lower markers of airway inflammation in young women.DesignWe carried out a cross-sectional analysis on a sub-cohort of participants enrolled in a randomized controlled trial in rural Guatemala, RESPIRE.ParticipantsWe recruited 45 indigenous women at the end of the 18-month trial; 19 women who had been using the chimney stove for 18–24 months and 26 women still using open fires.MeasurementsWe obtained spirometry and induced sputum for cell counts, gene expression of IL-8, TNF-α, MMP-9 and 12, and protein concentrations of IL-8, myeloperoxidase and fibronectin. Exhaled carbon monoxide (CO) and 48-hr personal CO tubes were measured to assess smoke exposure.ResultsMMP-9 gene expression was significantly lower in women using chimney stoves. Higher exhaled CO concentrations were significantly associated with higher gene expression of IL-8, TNF-α, and MMP-9. Higher 48-hr personal CO concentrations were associated with higher gene expression of IL-8, TNF- α, MMP-9 and MMP-12; reaching statistical significance for MMP-9 and MMP-12.ConclusionsCompared to using an open wood fire for cooking, use of a chimney stove was associated with lower gene expression of MMP-9, a potential mediator of airway remodeling. Among all participants, indoor biomass smoke exposure was associated with higher gene expression of multiple mediators of airway inflammation and remodeling; these mechanisms may explain some of the observed association between prolonged biomass smoke exposure and COPD.

Highlights

Household air pollution from cooking with solid fuel is estimated to be responsible for 4.6% of worldwide disability adjusted life-years lost. [1] This is due to acute lower respiratory infections (ALRI) in children, chronic obstructive pulmonary disease (COPD), lung cancer, cataracts, and cardiovascular disease in adults. [2] More than twofifths of the world’s population uses solid fuel as their primary fuel for cooking and the vast majority of these people do so over open fires indoors. [3] This inefficient way of cooking exposes women on a daily basis to high levels of smoke
Higher exhaled carbon monoxide (CO) concentrations were significantly associated with higher gene expression of IL-8, tumor necrosis factor (TNF)-a, and matrix metalloproteinase (MMP)-9
Higher 48-hr personal CO concentrations were associated with higher gene expression of IL-8, TNF- a, MMP-9 and MMP-12; reaching statistical significance for MMP-9 and MMP-12

Summary

Introduction

Household air pollution from cooking with solid fuel (wood, dung, crop residues, coal, charcoal) is estimated to be responsible for 4.6% of worldwide disability adjusted life-years lost. [1] This is due to acute lower respiratory infections (ALRI) in children, chronic obstructive pulmonary disease (COPD), lung cancer, cataracts, and cardiovascular disease in adults. [2] More than twofifths of the world’s population uses solid fuel as their primary fuel for cooking and the vast majority of these people do so over open fires indoors. [3] This inefficient way of cooking exposes women (who tend to perform the majority of cooking) on a daily basis to high levels of smoke. Epidemiologic studies of women from developing countries have shown strong associations between use of biomass cooking fuel and chronic bronchitis and/or COPD. [19] More recently, observational studies of individuals in West Bengal, India exposed to a combination of solid fuel types (wood, dung, and crop residues) found an increase in inflammatory cells and other markers of inflammation in expectorated sputum, including total cell counts, leukocyte counts, and sputum levels of interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-a, and reactive oxygen species after adjustment for confounders, though this study was limited by significant differences between the biomass smoke-exposed and comparison (liquid petroleum gas stove) groups at baseline. The resulting biomass smoke exposure is a major cause of chronic obstructive pulmonary disease (COPD) among women in developing countries

Results

Discussion

Conclusion