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Introduction to the Second Bill Morgan Memorial Special Issue: an update on low dose biology, epidemiology, its integration and implications for radiation protection

Dr. William Francis Morgan, known as Bill by many of his friends and colleagues, was a leading figure in the field of radiation research. He passed away on 13 November 2015, at the age of 62 years (Hamada et al. 2016, 2017). His work spanned the range of radiation biology from cell and animal studies to impacts of the work on radiation protection. Bill’s expertise and experience in low dose radiation effects were extremely valuable in reviewing and providing scientific insights. Thus, he served on many national and international radiation protection committees. To commemorate the first anniversary of his passing, the first two-part Bill Morgan Memorial Symposium was held in October 2016 in Kona, Hawaii, USA, during the 62nd Annual Meeting of the Radiation Research Society (RRS): part one was on ‘Biology, Epidemiology and Radiation Protection’ (Held and Hamada 2017), part 2 on ‘Low Dose Epidemiology’ (Salomaa et al. 2017). In October 2017, the first Bill Morgan Special Issue consisting of 18 articles was published in the International Journal of Radiation Biology (available at https://www.tandfonline.com/toc/irab20/93/10). On the fifth anniversary of Bill’s passing, the second twopart Bill Morgan Memorial Symposium was held in October 2020 during the 66th Annual Meeting of the Radiation Research Society. The plan was to hold a face-to-face meeting in Kona, Hawaii, USA, but due to the pandemic of SARS-2 coronavirus disease 2019 (COVID-19) this was changed to a fully virtual meeting. Part 1 was on ‘Low dose biology, epidemiology, its integration and implications for radiation protection: an update’, co-chaired by Evagelia C. Laiakis and Nobuyuki Hamada (Laiakis et al. 2021). Part 2 was on ‘Epidemiology: Updates on epidemiological low dose studies’, co-chaired by Cato M. Milder and Mark P. Little (Milder et al. 2021). This second Bill Morgan Special Issue consists of two meeting reports (Laiakis et al. 2021; Milder et al. 2021), four review articles highlighted from recorded presentations in parts 1 and 2 (Chauhan, Villeneuve, et al. 2021; Kendall et al. 2021; Little et al. 2021; Paunesku et al. 2021), three original articles (Chauhan, Vuong, et al. 2021; Golden et al. 2021; Karpov et al. 2021) and one review article (Preston et al. 2021). In this Special Issue, Paunesku et al. (2021) give an overview regarding cancer effects of low dose and low dose rate low linear energy transfer (low-LET) radiation in animal models. Chauhan, Vuong, et al. (2021) report protein level changes in human lens epithelial cells exposed to X-rays at various dose rates. Kendall et al. (2021) give an overview of epidemiological studies on childhood cancer and natural background radiation. Little et al. (2021) give an overview of epidemiological studies on lowand moderate-dose noncancer effects of radiation in directly exposed individuals, especially circulatory and ocular diseases. Golden et al. (2021) provide a cohort profile for four early uranium processing facilities in the US and Canada. Karpov et al. (2021) provide descriptive characteristics of occupational exposures and medical follow-up in a new cohort of workers from the Siberian Group of Chemical Enterprises in Seversk, Russia. Toward integrating radiation biology and epidemiology, Preston et al. (2021) give an overview of NCRP Report No. 186 (NCRP 2020), with focus on the adverse outcome pathways (AOPs) and key events approach. Finally, Chauhan, Villeneuve, et al. (2021) consider the need of collaborative efforts among the scientific community to advance the AOP concept in areas of radiation risk assessment. Last but not least, we are indebted to the distinguished authors for their invaluable contributions, and are grateful to the expert reviewers for their cooperation, dedication and constructive comments. We wish to acknowledge the International Journal of Radiation Biology for the opportunity to guest edit this Special Issue, and extend our special thanks in this respect to Gayle E. Woloschak (the Editor-inChief of the journal) and Dianne Dixon (the Managing Editor of the journal). Many thanks are also due to RRS for two symposium sessions. Without contributions from all of them, this Special Issue could not have come out in such good shape. We dedicate this Special Issue to our colleague and friend, Bill Morgan.