TG 115: Risk and Dose Assessment for Radiological Protection of Astronauts

During the past six decades, many human spaceflights have been launched. Among the factors that affect health and performance of astronauts during and after their space missions, space radiation presents unique challenges. ICRP Publication 123 (2013) addressed the challenges in the assessment of space radiation exposure to astronauts, covering radiation environments in space, quantities used in radiological protection, methods of measurement, radiation fields inside spacecraft and on planetary surfaces, radiation fields and doses in the human body, and a short section on operational radiological protection.

Currently, space agencies involved in human spaceflight use a variety of methods and quantities to assess dose and risks to their astronauts, as well as a variety of restrictions in the management of human spaceflights. In 2018, agencies involved in the International Space Station (ISS) proposed collaboration with ICRP to examine effects that may impact crew health and mission success, and to develop a common health risk assessment framework and recommendations on exposure limits for exploration-class human spaceflight missions. In response, ICRP established TG115 Risk and Dose Assessment for Radiological Protection of Astronauts to develop a comprehensive framework for risk and dose assessment for radiological protection of astronauts, including a set of basic objectives, a review of the current understanding of effects and risks from space radiation, a broadly-applicable risk and dose assessment methodology, and an assessment of the use of risk as a radiological protection quantity. Health endpoints considered by TG115 include cancer, however, the intent is to broaden the scope to include additional endpoints including potential tissue effects.

This paper provides an update on current activities of TG115. It is envisaged that, on the long-term, TG115 will address how the principles of radiological protection are applied to space environment. The effort may lead to recommendations on setting and using numerical values of limits, constraints, and reference levels. This would mirror ICRP Publication 132 (2016), where radiological protection from cosmic radiation in aviation is addressed.