EXPERIMENTAL PATHOLOGY Acute effects of environmental tobacco smoke and dried dung smoke on lung histopathology in rabbits FATMA FI ˙ DAN*, MEHMET UNLU*, MURAT SEZER*, ONDER SAHI ˙ N{,CI ˙ GDEM TOKYOL{ AND HI ˙ DI ˙ R ESME{ Afyon Kocatepe University Faculty of Medicine, Departments of *Pulmonary Medicine, {Pathology, and {Thoracic Surgery, Afyon, Turkey Summary Aims: To compare the effects of cigarette smoke and dried dung smoke exposure on the histopathology of lungs. Methods: Three groups each with five rabbits were formed. The cigarette smoke group was exposed to cigarette smoke, the biomass group was exposed to dried dung smoke and the control group was exposed to dry air 1 hour daily for 1 month. At the end of 1 month, animals were sacrificed and lung tissues were examined histopathologically. Results: Histopathological evaluation of rabbits’ lungs revealed that intraparenchymal vascular congestion and thrombosis, intraparenchymal haemorrhage, respiratory epithelial proliferation, number of macrophages in the alveolar and bronchial lumen, alveolar destruction, emphy- sematous changes and bronchoalveolar haemorrhage scores were significantly increased in rabbits exposed to cigarette smoke compared with the control group. Res- piratory epithelial proliferation, alveoli destruction and emphysematous change scores were significantly increased in rabbits exposed to dried dung smoke compared with the control group. Conclusion: Although less than the effects of cigarette smoke, dried dung smoke had severe histopathological effects on rabbits’ lungs. Key words: Cigarette smoke, dried dung, histopathology, lung, rabbit. Received 15 July, revised 14 September, accepted 17 September 2005 INTRODUCTION The hazardous effects of smoking tobacco have been recognised for centuries. The associations between tobacco smoke, bronchogenic carcinoma and obstructive airway diseases have been widely reviewed; the pathology and imaging characteristics of these disorders are well known. However, there is increasing awareness of the potential for cigarette smoke to cause pulmonary diseases other than lung cancer, chronic bronchitis and emphysema. 1 Besides cigarette smoke, exposure to biomass combustion products may also play an important role in the aetiology of both acute and chronic respiratory diseases. 2–5 Approximately 50% of the world’s population and up to 90% of rural households in developing countries still rely on unprocessed biomass fuels in the form of wood, dung and crop residues. 6 These are typically burnt indoors in open fires or poorly functioning stoves. As a result, there are high levels of air pollution to which women, especially those responsible for cooking, and their young children, are most heavily exposed. 7 Biomass fuel is any material derived from plants or animals which is deliberately burnt by humans. Wood is the most common example, but the use of animal dung and crop residues is also widespread. 8 Many of the substances in biomass smoke can damage human health. The most important are particles, carbon monoxide, nitrous oxides, sulphur oxides (principally from coal), formaldehyde, and polycyclic organic matter, includ- ing carcinogens such as benzo(a)pyrene. 8 A health effect is determined not just by the pollution level but also, and more importantly, by the time people spend breathing polluted air, i.e., the exposure level. People in developing countries are commonly exposed to very high levels of pollution for 3–7 hours daily over many years. 9 During winter in cold and mountainous areas, exposure may occur over a substantial portion of each 24-hour period. 10 Many studies report that excessive exposure to biomass smoke has the same health risk as exposure to cigarette smoke. 11 The risk of acute respiratory infections, chronic pulmonary disease, asthma, cancer (lung, nasopharyngeal and laryn- geal cancer), pulmonary tuberculosis, low birth weight and infant mortality, and cataracts increases with biomass exposure. 7 In Turkey, dried dung is used for heating, as well as cooking meals and bread. Women seem to be more often exposed to smoke because they are generally responsible for cooking. The aetiology of chronic pulmonary disease and associated cor pulmonale in women from rural areas who are non-smokers is thought to be the inhalation of noxious gases from burnt substances such as dried dung; however, it is yet unclear which physiopathological mechanisms are involved in this process. 12 In our study, we aimed to compare the effects of ciga- rette smoke and dried dung smoke exposure on lung histopathology. MATERIALS AND METHODS All procedures were carried out according to institutional approval. Adult male New Zealand White rabbits with weights ranging from 1.5 to 2 kg were used. There were three groups each with five rabbits. Animals were fed rabbit chow and water. The cigarette smoke (CS) group was exposed Pathology (February 2006) 38(1), pp. 53–57 ISSN 0031-3025 printed/ISSN 1465-3931 # 2006 Royal College of Pathologists of Australasia DOI: 10.1080/00313020500459615