Biomarkers may be an early warning for lung injury in Ground Zero rescue workers

For the firefighters who responded to the World Trade Center disaster on September 11th, 2001, certain blood biomarkers may be a sign of accelerated loss of lung function and airway obstruction, according to research published in the Annals of the American Thoracic Society.

The study followed more than 9,000 firefighters until September 10, 2016.

In the aftermath of 9/11, New York City fire department rescue and recovery workers who were exposed to caustic dust at the site had high rates of lung injury and excessive loss of lung function. Lung function stabilized in a majority of those workers after 2002. However, some continued to lose lung function at an accelerated rate, while some improved.

"We have previously observed some of our patients were doing worse than others and performed this study because we wanted to understand factors that increased the risk for excessive lung function loss," said senior study author Michael D. Weiden, MS, MD, associate professor of medicine and environmental medicine at New York University and a New York City Fire Department medical officer. "These findings could motivate future research to find other treatments for this group with ongoing lung injury."

The goal of the study was to determine whether these different trajectories were associated with blood concentrations of eosinophils and neutrophils, two types of immune cells that play a role in many respiratory diseases and are routinely measured during medical evaluations.

The study found:

• 12.7% of participants experienced accelerated FEV₁ loss (>64 mL/year loss beyond expected), while 8.3% showed improvement in FEV₁, the maximum amount of air that can be exhaled in one second.
• Elevated blood eosinophil (≥300 cells/µL) and neutrophil (≥4,500 cells/µL) concentrations were both associated with accelerated FEV₁ decline.
• Higher eosinophil, but not neutrophil, concentrations correlated with airflow obstruction, defined as FEV₁/FVC <0.70.
• Individuals with accelerated FEV₁ decline were more than four times as likely to have airflow obstruction as those who had expected FEV₁ decline.
• In a subset of firefighters (4,303) who had pre-9/11 CBC results, there was an association between elevated eosinophil and neutrophil levels before and after 9/11.
• Higher levels before 9/11 were associated with accelerated FEV₁ decline.

The study adjusted for several factors, including age, race, length of Ground Zero exposure, and smoking. There were significant interactions between smoking, eosinophil and neutrophil concentrations, and FEV₁ decline.

"After 9/11, about one in eight firefighters who worked at the World Trade Center had accelerated loss of lung function over the next 15 years," Dr. Weiden said. "Even in those who had never smoked, we found that accelerated loss of lung function increased their risk of airway obstruction and COPD [chronic obstructive pulmonary disease]."

The authors said the study may not be generalizable to another population exposed to caustic dust because of the massive nature of exposure and because the majority of the firefighters were previously healthy white men.

To read more about this study, click here.