Biometric monitoring in silicosis to detect early disease and monitor lung injury: not quite there

From the authors: We would like to thank D. Weiler Ravell and H. Bishara for their comments about our recent paper [1], and take this opportunity to reply. While their observation that 63.2% of our cohort already had silicosis negates the definition of “early diagnosis” is correct, 36.8% of the exposed workers had neither a previous diagnosis of silicosis nor clinical symptoms, and they were considered “healthy workers” and, as such, they are monitored by spirometry and chest radiographic findings once in 3 years. Our biomarker revealed that they had exposure-induced inflammation and a high load of hazardous dust in the airways, thus alerting for close monitoring and medical observation and, most importantly, precautionary measures at the workplace. In Israel, the manufacture of kitchen and bath countertops is based mainly on artificial stone that contains 93% silica as natural quartz, and ∼3500 workers are currently involved in cutting and processing it. We estimate that there should be more than 1000 “healthy workers” exposed to artificial stone dust who already have inflammatory abnormalities and high load of dust in their airways. We claim that implementation of the preventive biomonitoring measures that we recommend are sensitive and that the early detection that they enable may lead to avoidance or slowing down of the disease process. We cite two of our earlier works [2, 3] to support our claim that the neutrophil count is a robust biomarker to detect time-dependant occupational exposure to hazardous dust. The first report was on firefighters that were on duty during the World Trade Center collapse: their neutrophil count was correlated to the time of working at “ground zero” [2]. In the second report, the neutrophil count was correlated to the years of exposure to airborne particles in the workplace of a cohort of welders [3].