Toxicology in Vitro 21 (2007) 586–594 www.elsevier.com/locate/toxinvit 0887-2333/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.tiv.2006.12.002 Cytotoxicity and DNA-damage in human lung epithelial cells exposed to respirable -quartz Carla Fanizza a,¤ , Cinzia Lucia Ursini b , Emilia Paba a , Aureliano Ciervo b , Arianna Di Francesco b , RaVaele Maiello b , Paolo De Simone a , Delia Cavallo b a Department of Occupational Hygiene, ISPESL, National Institute for Occupational Safety and Prevention, Via Fontana Candida 1, 00040 Monteporzio Catone, Rome, Italy b Department of Occupational Medicine, ISPESL, National Institute for Occupational Safety and Prevention, Via Fontana Candida 1, 00040 Monteporzio Catone, Rome, Italy Received 3 July 2006; accepted 10 December 2006 Available online 16 December 2006 Abstract Occupational exposure to respirable crystalline silica is associated with the development of silicosis, lung cancer and airways diseases. In order to assess cytotoxic eVects and direct–oxidative DNA damage induced by short-term exposure to diVerent doses of respirable - quartz (NIST SRM1878a), we conducted a study using A549 cells. The cells were exposed to -quartz at 25, 50, 100 g/ml for 4 h and ana- lysed by scanning electron microscope (SEM) and LDH release assay for cytotoxic eVect evaluation. Cells were also exposed to 10, 25, 50, 100 g/ml of -quartz for 2 h and 4 h and analysed by Fpg comet test to evaluate direct and oxidative DNA damage. SEM observations of treated cells showed bleb development at lower doses and alterations of microvilli morphology at the highest dose. A slight LDH release was found only at 100 g/ml. Fpg comet test showed a dose-related oxidative DNA damage in cells exposed for 2h to quartz. Cells exposed for 4 h at the same concentrations showed a dose-related direct DNA damage and the presence of oxidative DNA damage at lower doses. The bleb induction on cell surface evidenced by SEM at lower doses correlates with the presence of oxidative DNA damage at 4 h. The cell surface modiWcations observed by SEM at 100 g/ml indicate that high doses of quartz induce more evident cytotoxic eVects conWrmed by LDH analysis and correlate with the genotoxicity showed by comet assay.  2006 Elsevier Ltd. All rights reserved. Keywords: Respirable quartz; Direct–oxidative DNA damage; Cytotoxicity; SEM analysis; Comet assay 1. Introduction Crystalline silica is a ubiquitous substance which is the basic component of sand, quartz and granite rock. Long- term exposure to respirable crystalline silica is known to cause Wbrosis and silicosis (Finkelstein, 1995; Steenland and Brown, 1995; Kreiss and Zhen, 1996; Rosenman et al., 1996; Chen et al., 2001; ‘t Mannetje et al., 2002; Nij and Heederik, 2005). Other diseases have been associated with occupational silica exposure such as lung cancer, pulmo- nary tuberculosis, chronic obstructive pulmonary disease and autoimmune diseases (for example systemic lupus ery- thematosus and rheumatoid arthritis). Occupational expo- sure to crystalline silica occurs in electronics, mining, maritime, construction, use and manufacture of abrasives and agriculture. There are an estimated 3.2 million workers exposed in the European Union (IARC, 1997), and 1.7 mil- lion in the United States (Kauppinen et al., 2000). The Occupational Safety and Health Administration (OSHA) established an 8-h TWA permissible exposure limit (PEL) of 0.1 mg/m 3 for respirable crystalline silica, the National Institute for Occupational Safety and Health (NIOSH) has recommended an exposure limit of 0.05 mg/m 3 . In 2006 the American Conference of Governmental Industrial Hygienist * Corresponding author. Tel.: +39 6 94181598; fax: +39 6 94181419. E-mail address: carla.fanizza@ispesl.it (C. Fanizza).