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Aerodynamic diameter is a major determinant of particle and fiber deposition and toxicity in the respiratory tract. To characterize cellulose acetate fibers released from the filter end of cigarettes puffed under conditions approximating smoking, we designed multistage impactors to determine the aerodynamic diameters of large fibers with circumscribed diameters between 20 and 35 microm and aspect ratios ranging from subfiber ratios up to 40. This range of diameters encompasses all of the cellulose acetate fiber sizes that are commercially manufactured. When commercially available cigarettes with filters made from acetate fibers in this circumscribed diameter range were puffed directly into the impactor, on average 10 fibers/cigarette were released and their aerodynamic diameters were determined. In our studies, we found that the aerodynamic diameters of the cellulose acetate fibers were always greater than 23 microm. Using standard lung deposition models, we concluded that the fibers are nonrespirable with a very low probability of penetration to the distal lung. Our findings, which demonstrate release of only a small number of these large fibers with an extremely low likelihood of reaching the distal lung, indicate that these fibers are not a risk for human lung disease.

Introduction: From October 1992 to September 1993 clinical observations of the civil population of Cienfuegos revealed the presence of epidemic neuropathy (EN) reaching about 2,000 patients. The clinical manifestations were not uniform. Although numerous studies have been carried out in our country, none have established the characteristics of EN 'the peripheral form'., Material and Methods: We studied the first 50 patients assisted by the neurological services of the clinical surgical hospital Dr. Gustavo Aldereguia Lima of Cienfuegos diagnosed of EN 'peripheral form' according to the procedure established by Ministry of Public Health of Cuba. A clinical history was made for each patient consisting of: General data, history of toxic, nutritional, malabsorption factors and chronic illnesses; symptoms and a neurological examinations. Laboratory test, in a group of patients, were done in sera, urine, cerebrospinal fluid (CSF), gastric juice and neurophysiological studies that included computerized evoked potentials and electroencephalograms registers., Results: Upon analysis of the clinical history, nutritional factors was common to all the patients associated to toxic and malabsorption. The clinical forms were neuropathy (NP) 48%, myeloneuropathy (MNP) 42% and myelopathy (MP) 10%. Retrobulbar optic neuropathy was observed in 42% of the patients and auditory neuropathy in 22%., Conclusions: The clinical characteristics of NP, in our cases, indicated that this disease fundamentally affects the sensorial neurons and the sensitive peripheral nerves, bilaterally, symmetrically, distally and predominantly in lower limbs. The pathological process has been associated with a distal axonopathy. However, clinic signs of myelopathy can be found up to 40% frequently combined with neuropathy or in isolated form, and seems to affect the posterior and lateral columns of the spinal cord, mainly at thoraciclumbar level. Neuropathy of central nervous system is unknown since no patient has died of EN.