For more than a century, radiation health has been a concern for the public and for workers. However, the launch of the Hollywood film Oppenheimer, the announcement of the release of radioactive water from the recovery efforts at the Fukushima Daiichi nuclear power plant in Japan, a new study of radionuclides in river sediment, and naturally occurring radiation associated with reusing and extracting critical materials from solid wastes are bringing renewed attention to this topic.
An earthquake and tsunami destroyed the Fukushima Daiichi nuclear power plant in 2011. This catastrophe, along with the emergency cooling actions, left behind water contaminated with radiation from the reactor fuel rods. Since the accident, Tokyo Electric Power Company (TEPCO) has been distilling and filtering the radioactive water to remove most isotopes, although tritium remains, because it is difficult to remove from water. TEPCO has now been approved to start releasing approximately 340 million gallons of contaminated water to the Pacific Ocean. This approval was based on a comprehensive dose and risk assessment reviewed by the International Atomic Energy Agency (IAEA).
Many substances or products that originate from the earth contain some level of radiation. We cannot escape exposure to radiation. In fact, we are always exposed to natural background levels, but with careful analysis, we can be protected from dangerous exposures as we safely manage the use of radioactive materials in our daily lives.
Deciding how to handle materials containing radiation typically requires a quantitative health risk assessment. After identifying the isotopes involved and their radiation profiles, exposure and health scientists evaluate multiple exposure pathways to conservatively estimate how radiation may reach the environment and the potential for exposure. Radionuclides decay and form new isotopes over time which can have long half-lives. Therefore, exposure (dose) assessments must consider the life cycle of the materials themselves, as well as any products in which they are used. Estimated exposures are compared against dose standards established by international scientific agencies to be protective of sensitive human and ecological populations, to determine whether a lifetime of exposure would be considered safe. In the Fukushima Daiichi plant case, TEPCO has been approved, based on a risk assessment, to dilute the water until tritium levels fall below regulatory limits, and then to slowly release it.
A risk assessment approach may also be used to assess the potential for risks when materials such as mining wastes and processing residues are recycled in support of circular economy efforts. For example, Marschke et al. (2019) demonstrated the safe reuse of alumina processing residues (red mud) in cement over its life cycle. In addition, ToxStrategies’ scientists have prepared risk assessments of potential radiation exposures from naturally occurring radium in brines used for road deicing, accumulation of uranium and radium in crops from irrigation water and conducted dose reconstruction to characterize potential risk associated with releases from the Oak Ridge and Rocky Flats National Laboratories.
ToxStrategies has recently welcomed Mr. Alan Hale, a Certified Health Physicist, to our team. Mr. Hale and other radiological health scientists at ToxStrategies have the expertise to support a wide variety of risk assessments. For more information, contact LeeAnn Racz (lracz@toxstrategies.com) or William Rish (wrish@toxstrategies.com).