Additive effects of exposure to silica dust and smoking on pulmonary epithelial permeability: a radioaerosol study with technetium-99m labelled DTPA.

Abstract

Background Increased pulmonary epithelial permeability evaluated by the rate of clearance from lung to blood of the radioaerosol solute technetium-99m labelled diethylenetriamine pentacetate (99Tc-DTPA) has been reported in smokers and in workers exposed to silica dust. A study was carried out to determine whether there are additive effects of cigarette smoke and exposure to silica dust on clearance rates of 9mTc-DTPA in ceramic workers. Methods Thirty one subjects with silicosis were studied, of whom 18 smoked cigarettes and 13 were non-smokers. They had similar histories of exposure to silica dust, and radiological alterations consistent with silicosis. The results from these patients were compared with those from normal subjects and smokers previously studied by the authors. Results Pulmonary function values were normal in most patients and not significantly different among groups. The median (range) rate of clearance of ""mTc-DTPA in smokers with silicosis was 4 1 (1.9-12.7) %/olminute, which was higher than the rates in non-smoking patients with silicosis of 2*2 (1-1-6.6) 0/olminute and in smokers without exposure to silica dust of 2-9 (1.6-4.5) O/%l minute. These differences were more evident and significant when the clearance rates of the lower lobes of the three groups were compared. Clearance rates higher than 3%/olminute were much more frequent in smokers with silicosis (85%) than in non-smoking patients with silicosis (15%) and in smokers (40%). Conclusion In ceramic workers with radiographic changes resulting from exposure to silica dust, there is an additive effect of inhalation of silica dust and cigarette smoking on clearance rates of '-Tc-DTPA. (Thorax 1993;48:264-268) Accelerated clearance rates of small inhaled radioaerosol solutes from the lung to the blood have been used as an index of pulmonary epithelial permeability in patients with acute and chronic respiratory disease. Increased rates of clearance of the radionuclide technetium-99m labelled diethylenetriamine pentacetate (99mTc-DTPA) have been reported in infants and adults with the respiratory distress syndrome' 2; in patients with Pneumocystis carinii pneumonia,3 systemic sclerosis,4 sarcoidosis,56 and idiopathic pulmonary fibrosis;6 and after cytotoxic agents7 and amiodarone.8 Active cigarette smoking also causes an increase in alveolar epithelial permeability.' [10][11][12] We have recently reported that chronic exposure to silica dust may be related to accelerated clearance rates of this solute, even in the absence of radiographic changes.'2 Since smoking and exposure to respirable free silica dust appear independently to injure the lungs and cause accelerated solute clearance rates, our purpose was to determine if there is an additive effect on 99mTc-DTPA clearance rates in patients with silicosis who are smokers. Methods SUBJECTSSubjects were selected from 150 ceramic workers'3 14 who had had prolonged exposure to silica dust that exceeded the permitted threshold value for Brazil.'5 In addition to the occupational histo...

Interaction of cigarette smoke and house dust mite allergens on inflammatory mediator release from primary cultures of human bronchial epithelial cells

“…Mechanistic studies have demonstrated that cigarette smoke condensate significantly increases rat lung epithelial permeability, associated with a significant recruitment of neutrophils into the air‐spaces. Pulmonary epithelial permeability has also been shown to be increased in smokers when compared to non‐smokers [7]. Other studies have demonstrated increases in interleukin (IL)‐8 levels in bronchoalveolar lavage (BAL) fluid of smokers compared with that of non‐smokers [8,9], and a significant correlation between IL‐8 concentration and neutrophil count in bronchial samples of BAL fluid [9].…”

Serum levels of CC16, SP-A and SP-B reflect tobacco-smoke exposure in asymptomatic subjects

“…Acute, reversible changes in permeability probably arise through smoke-mediated release of vasoactive neuropeptides (tachykinins) [9] from sensory nerves in the airways whereas chronic increases may reflect early destruction of connective tissue in the alveoli [20][21][22]. Tars and other noxious substances in cigarette smoke increase the numbers of lung neutrophils in both symptomatic and asymptomatic smokers [23].…”

Association between Crystalline Silica Dust Exposure and Silicosis Development in Artificial Stone Workers

“…Several years ago, smoking was considered as a risk factor for the development of silicosis in workers exposed to silica dust [ 35 ]. Even low exposure levels of respirable crystalline silica have been associated with lung cancer [ 36 ].…”