Abstract We present the results of an experiment aimed at comparing the effects of different background radiation environments on metabolism and responses to γ-rays and cycloheximide of cultured mammalian cells. Chinese hamster V79 cells were maintained in exponential growth in parallel for up to 9 months at the Istituto Superiore di Sanità (ISS) and at the INFN-Gran Sasso underground Laboratory (LNGS) where exposure due to γ-rays and to radon was reduced by factors of about 70 and 25, respectively. | Radiat Environ Biophys (2002) 41:217–224 DOI O R I G I N A L PA P E R L. Satta · F. Antonelli · M. Belli · O. Sapora G. Simone · E. Sorrentino · . Tabocchini F. Amicarelli · C. Ara · . Cerù · S. Colafarina L. Conti Devirgiliis · A. De Marco · M. Balata A. Falgiani · S. Nisi Influence of a low background radiation environment on biochemical and biological responses in V79 cells Received: 14 December 2001 / Accepted: 1 June 2002 / Published online: 8 August 2002 © Springer-Verlag 2002 Abstract We present the results of an experiment aimed at comparing the effects of different background radiation environments on metabolism and responses to γ-rays and cycloheximide of cultured mammalian cells. Chinese hamster V79 cells were maintained in exponential growth in parallel for up to 9 months at the Istituto Superiore di Sanità (ISS) and at the INFN-Gran Sasso underground Laboratory (LNGS) where exposure due to γ-rays and to radon was reduced by factors of about 70 and 25, respectively. After 9 months the cells grown at the LNGS (cumulative γ dose about 30 µGy, average radon concentration around 5 Bq/m3), compared to the cells grown at the ISS (cumulative γ-ray dose about 2 mGy, average radon concentration around 120 Bq/m3), exhibited i) a significant increase of the cell density at confluence, ii) a significantly higher capacity to scavenge organic and inorganic hydroperoxides but a reduced scavenging capacity towards superoxide anions and iii) an increase in both the basal hprt mutation frequency and sensitivity to the mutagenic effect of γ-rays. The cells grown at the LNGS also showed a greater apoptotic sensitivity starting at the third month of culture, that was no longer detected after 9 months. Overall, these data L. Satta (✉) Energetics Department, Rome University “La Sapienza”, Via A. Scarpa 14, 00161 Rome Italy e-mail: Tel.: +39-064-9766560, Fax: +39-064-4240183 F. Antonelli · M. Belli · O. Sapora · G. .