Ultrafine particles in human lung macrophages

As knowledge about size dependency of particle toxicity continues to grow, attention has been focused on ultrafine particles (i.e., < 0.1 pm in diamet er). In recent studies with rats, investigators learned that ultrafine part icles likely have greater pulmonary toxicity than larger particles, and it is possible that exposure to, and accumulation of, these particles in the h uman lung may be associated with adverse respiratory health effects. As par t of an ongoing study, the authors performed bronchoalveolar lavage in 14 h ealthy current nonsmokers to investigate the extent to which ultrafine part icles were present in lung macrophages. In addition, 10 of the 14 subjects performed pulmonary function tests. Eleven of the 14 subjects were utility workers, and 3 were nonmaintenance employees of a university. The authors u sed a Zeiss CEM902 electron microscope to study macrophages isolated from b ronchoalveolar ravage fluid. Morphometric quantification revealed ultrafine particles in lung macrophages of all 14 volunteers; the average number of ultrafine particles/mum(3) cytoplasm per cell (UFavg) ranged from 34 to 231 (mean = 95, standard deviation = 54). Regression analysis showed that the UFavg was associated inversely with percent predicted forced expiratory vol ume in 1 second (FEV1.0) (beta = -1.2 percent predicted FEV1.0/10 ultrafine particles mum(3) cytoplasm per cell [standard error = 0.45, p = .03]). The demonstration of ultrafine particles in all 14 subjects, independent of oc cupational exposure, suggests that there is environmental exposure to ultra fine particles. The negative association between the number of ultrafine pa rticles and ventilatory function demonstrates a need for further investigat ion into the pulmonary health effects of ultrafine particles.