['1.5.', 'to', 'the', 'bronchial', 'epithelium.', 'The', 'short', 'time', 'period', 'and', 'limited', 'number', 'of', 'animals', 'tested', 'preclude', 'the', 'direct', 'extrapolation', 'of', 'these', 'results', 'to', 'human', 'smokers,', 'CONCLUSIONS', 'The', 'atcha', 'track', 'LR115', 'system', 'provided', 'good', 'visualization', 'of', 'the', 'pattern', 'of', 'the', 'cigarette', 'smoke', 'aerosol', 'in', 'the', 'tissues', 'examined,', 'No', 'hot', 'spots,', 'or', 'areas', 'of', 'accumulated', 'activity', 'in', 'the', 'rat', 'were', 'detected', 'along', 'the', 'airway', 'surfaces', 'that', 'we', 'examined,', 'Large', 'deposits', 'of', 'activity', 'were', 'seen', 'on', 'the', 'larynx', 'during', 'the', 'smoking', 'period,', 'For', 'the', 'pulmonary', 'con-', 'partment,', 'radiochemical', 'clearance', 'data', 'fit', 'a', 'model', 'with', 'two', 'phases', 'of', 'clearance.', 'Ty)>', '=', '19', 'days', '(90%)', 'and', 'Ty', ';)', '=', '125', 'days', '(10%).', 'This', 'agrees', 'qvalitatively', 'with', 'other', 'models,', 'It', 'is', 'interesting', 'that', 'the', 'Sum', 'ees', 'which', 'fit', 'the', 'clearance', 'data', 'cannot', 'fit', 'the', 'bodldeu', 'of', 'the', 'lung', 'burden,', 'It', 'is', 'assumed', 'that', 'the', 'effects', 'of', 'the', 'inhaled', 'aerosol', 'Sntonfered', 'with', 'clearance', 'during', 'the', 'smoking', 'period.', 'In', 'addition,', 'a', 'permanently', 'sequestered', '21059', 'burden', 'may', 'be', 'present', 'in', 'the', 'trachea,', '“Its', 'origin', 'is', 'unclear,', 'ACENOWLEDGEMENTS', 'The', 'authors', 'thank', 'Drs,', 'John', 'Benner', 'and', 'Marshall', 'Reese', 'who', 'did', 'the', 'inhalation', 'exposures,', 'Dr.', 'Katherine', 'Sydnor', 'who', 'performed', 'the', 'autopsies', 'and', 'Gordon', 'Cook', 'for', 'the', 'graphic', 'material.', 'We', 'are', 'grateful', 'to', 'Dr.', 'Tai', '~', '-', 'Chan', 'for', 'providing', 'measurements', 'of', 'the', 'rat', 'breathing', 'pattern,', 'and', 'Laraine', 'Wittrup', 'for', 'preparation', 'and', 'typing', 'of', 'the', 'text.', '9£0hO9Z102']