Picano et al. BMC Cancer 2012, 12:157 http://www.biomedcentral.com/1471-2407/12/157 R E V I E W Open Access Cancer and non-cancer brain and eye effects of chronic low-dose ionizing radiation exposure Eugenio Picano1*, Eliseo Vano2, Luciano Domenici3, Matteo Bottai4 and Isabelle Thierry-Chef5 Abstract Background: According to a fundamental law of radiobiology (“Law of Bergonié and Tribondeau”, 1906), the brain is a paradigm of a highly differentiated organ with low mitotic activity, and is thus radio-resistant. This assumption has been challenged by recent evidence discussed in the present review. Results: Ionizing radiation is an established environmental cause of brain cancer. Although direct evidence is lacking in contemporary fluoroscopy due to obvious sample size limitation, limited follow-up time and lack of focused research, anecdotal reports of clusters have appeared in the literature, raising the suspicion that brain cancer may be a professional disease of interventional cardiologists. In addition, although terminally differentiated neurons have reduced or mild proliferative capacity, and are therefore not regarded as critical radiation targets, adult neurogenesis occurs in the dentate gyrus of the hippocampus and the olfactory bulb, and is important for mood, learning/memory and normal olfactory function, whose impairment is a recognized early biomarker of neurodegenerative diseases. The head doses involved in radiotherapy are high, usually above 2 Sv, whereas the low-dose range of professional exposure typically involves lifetime cumulative whole-body exposure in the low- dose range of < 200 mSv, but with head exposure which may (in absence of protection) arrive at a head equivalent dose of 1 to 3 Sv after a professional lifetime (corresponding to a brain equivalent dose around 500 mSv). Conclusions: At this point, a systematic assessment of brain (cancer and non-cancer) effects of chronic low-dose radiation exposure in interventional cardiologists and staff is needed. Keywords: Brain cancer, Cognitive effects, Interventional cardiologist, Radiation exposure, Risk Review The characterization of health effects (cancer and non- cancer) of chronic low-dose radiation (LDR) is still in- complete and difficult. The UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) 2009 clearly recommends paying more attention “to other non-cancer disease entities, in addition to circula- tory diseases”, encouraging “future epidemiological stud- ies designed to assess clinical and subclinical endpoints, as well as biomarkers, since this information is more likely to lead to insights” [1]. In 2006 the National Academy of Sciences BEIR VII committee identified as one of the top ten research needs “future occupational radiation studies”, which should include highly exposed populations with full record of exposure and well-suited to assessing the effects * Correspondence: picano@ifc.cnr.it 1Institute Clinical Physiology of the National Research Council CNR, 56124 Pisa, Italy Full list of author information is available at the end of the article of long-term, low-level radiation exposure in humans [2]. The International Commission on Radiological Protection (ICRP) stated in 2011 that “particular attention should be paid to radiation effects in the lens of the eye and on the cardiovascular system, because of recent published observa- tions of radiation effects in these systems occurring at much lower doses than reported previously”, and that brain ir- radiation can have direct radiation effects on the thyroid and pituitary glands, as well as subtle effects on the hypo- thalamic-pituitary-adrenal axis and the hypothalamic, pitu- itary-gonadal axis [3]. Within the general framework of the still-elusive assess- ment of cancer and non-cancer effects of LDR, high and unprecedented levels of radiation exposure in the contem- porary population of interventional cardiologists and other paramedical staff working at the catheterization laboratory clearly represent a challenge and an opportunity, especially if we wish to characterize the brain effects of LDR. The brain is a paradigm of a highly differentiated organ with © 2012 Picano et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.