Propylene oxide lowers lung function in urban residents
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Key takeaways:
- Higher levels of a biomarker for propylene oxide signaled worse measures of FVC and FEV1.
- This relationship is “partially mediated” by oxidative DNA damage and protein carbonylation.
Residents in urban areas experienced reductions in lung function when exposed to increased levels of propylene oxide, according to study results published in CHEST.
Propylene oxide (PO) is primarily found in traffic fumes, cigarettes, food fumigation and medical disinfection residues, according to researchers.
“This is the first study to provide epidemiological evidence on the relationship between PO exposure and lung function in the general population, and we found oxidative DNA damage as well as protein carbonylation partially mediated PO exposure-associated lung function decline,” Weihong Chen, MD, PhD, chief of the department of occupational and environmental health at the School of Public Health at Tongji Medical College, told Healio. “This study underscores the importance of PO exposure control to prevent the adverse effect of PO exposure on the respiratory system.”
Using a linear mixed model, Chen and colleagues assessed 3,692 (mean age, 53.08 years; 30.61% men) adult community residents in China to see if a PO internal exposure biomarker — urinary PO metabolite (N-Acetyl-S-[2-hydroxypropyl]-L-cysteine [2HPMA]) — was linked to reduced lung function at baseline and at 3 years (n = 1,540).
To account for potential covariates, researchers adjusted the model for age, sex, height, weight, smoking status, passive smoking, drinking status, physical activity, self-cooking, daily traffic exposure time, heart disease and lung diseases.
Researchers also sought to find out whether biomarkers of oxidative DNA damage (urinary 8-hydroxy-deoxyguanosine), lipid peroxidation (urinary 8-iso-prostaglandin-F2 alpha) and protein carbonylation (plasma protein carbonyls) in residents (n = 3, 364) mediated the link found between PO exposure and lung function.
When evaluating baseline measurements, researchers found that every threefold rise in urinary 2HPMA led to a 26.18 mL (95% CI, –50.55 to –1.81) decline in FVC and a 21.83 mL (95% CI, –42.71 to –0.95) decline in FEV1 (P < .05 for both).
On the other hand, PO exposure was not significantly linked to either FEV1/FVC or percent-predicted measures.
The relationship between 2HPMA and declines in FVC and FEV1 was no longer statistically significant at the 3-year mark, but researchers did find that persistently higher 2HPMA in adults led to a significant 1.8% decline in FEV1/FVC at this time (P < .05).
Notably, adults who reported never smoking, as well as adults who reported never passive smoking, also demonstrated the same significant relationships observed during each period.
During mediation analysis, researchers found that both biomarkers of oxidative DNA damage and protein carbonyl partially mediated FEV1 decline linked to PO exposure (mediation proportion, 6.81% and 3.44%). Oxidative DNA damage also had the same effect on FVC decline related to PO (mediation proportion, 5.48%).
“PO exposure in the general population is a previously neglected public health problem, but it needs more attention in the future given that we found it was related to respiratory impairment,” Chen told Healio. “Future studies are needed to identify subgroups prone to respiratory impairment from PO exposure, as well as to identify modifiable factors that may alleviate or counteract such impairment, thereby facilitating precise prevention strategies.”
This study by Liu and colleagues brings attention to environmental and occupational PO exposures as public health concerns, emphasizing the importance of further research across different areas of the world, according to an accompanying editorial by Luc Dauchet, MD, PhD, of University of Lille in France.
“To better estimate the public health impact of PO, this association should be studied in (for example) western populations, among whom the level of exposure might be different,” Dauchet wrote.
“With a view to confirming the reproducibility of this association and evaluating levels of exposure in other populations, more epidemiologic data are required,” Dauchet added. “This work might help to reinforce measures for reducing residential exposure and food contamination and thus might produce public health benefits.”