 Cells exposed to sidestream smoke experienced oxidative stress, which further allowed for DNA damage as well as cell transformation and an uncontrolled cell proliferation.Such DNA mutations and uncontrolled cell division resulting from exposure to sidestream smoke may result in cancerous tumours.During the 1980s the Philip Morris Tobacco Company carried out research on sidestream smoke at the Institut für Biologische Forschung, although this was not voluntarily published.