The connection between policymakers, scientists and the public is essential in advancing innovative technology and policy to solve complex problems including climate change, energy justice, cancer, Parkinson’s disease, and to keep workers and the public safe from exposure to low-dose radiation (LDR). Although these may initially appear as disparate policy problems, one common thread exists in relation to LDR exposure (below 100 mGy), and specifically surrounding its science.

Mostly, people are exposed to LDR when taking air flights and during health interventions including medical and dental X-rays, testing for medical conditions such as Parkinson’s, and cancer treatments. Everyday millions of people might be exposed to LDR when living in close proximity of uranium mining operations, nuclear power plants, or nuclear storage facilities. There have been historic radiation exposure events including Hiroshima, Chernobyl, and Fukishima that have exposed people over long periods of time to LDR.

Classical research focuses on risk of cancer and radiation-induced DNA damage of exposure that has informed policy. A linear ‘no threshold’ assumption currently exists in relation to exposure to radiation either at work (when employed in occupations in the medical field where exposure occurs on a daily basis), or in relation to proximity to nuclear plants (when establishing disaster and emergency planning areas in proximity to nuclear installations). The linear ‘no threshold’ assumption posits that exposure to radiation can only be detrimental and the health risks resulting are linearly proportional to exposure dose.  New science challenges the current linear toxicity paradigm and it is clear more research is required.

However, evidence suggests that at low doses, there is an absence of biological detriment, or even beneficial effects following exposure to LDR. It is now widely accepted that radiation also produces a wide range of epigenetic effects, effects on inflammatory processes, and effects on the cellular immune system (NEA 2007).

There is much that is unknown. Radiation is a carcinogen at high doses, but a weak carcinogen with no explicit and unambiguous evidence to support the suggestion that radiation exposures to background levels are damaging to health (Priest and Peckover 2004). While excess cancer has been detected in relation to Japanese atomic bomb survivors receiving radiation doses up to five times higher than occupational dose limits, there has been little impact on longevity in the population and these populations have tended to survive longer than unirradiated populations living around the impacted Japanese cities (Jordan 2016). Most epidemiological studies relate to LDR and cancer, but what of the incidence of other diseases, or the lack thereof?  

The development and spread of cancer is a complex process involving change within the genome, tissue-tumour microenvironment, and external factors such as avoiding removal by the immune system and the presence of inflammatory processes that aid cancer development.  Many questions exist on how LDR impacts these processes.  An example of uncertainty surrounds the conversion of LDR-induced molecular changes, such gene expression, DNA damage, protein levels, to health outcomes, such as cancer or cardiovascular disease. Questions also exist in relation to how LDR changes stem cell quality, cell and tissue aging? Are there differences between individuals due to natural genetic variants (e.g. Short Nucleaotide Polymorphisms that account for 90% of human genetic variability).

Given the uncertainty of the science, and some recent evidence to suggest that the current low dose, toxicity paradigm may be in error, it is widely recognized that research is required to address the consequences of exposures to LDR and to reduce uncertainties. Social science research explores perceptions surrounding LDR with implications beyond the health field into the climate change mitigation field.  

Social science establishes that fear or dread, uncertainty, and time frame (immediate versus long term) of consequences of radiation exposure impact people’s perception of risk; who communicates information relevant to risk construction  and the source of information are key determinants of people’s perceptions of the veracity of information (Takebayashi et al. 2017). As the degree of benefit associated with the exposure increases, the degree of risk acceptance increases, thus explaining why exposure through medical interventions is accepted. 

Climate change increasingly poses risk to humans in relation to extreme climate events (such as droughts and floods), food security (reducing crop yields in mid latitude regions), health and migration.  The Paris Agreement entails efforts to limit global warming well below 2 degrees Celsius through reducing Greenhouse Gas Emissions.  While nuclear energy is a proven low to zero carbon source of power, its further deployment in many areas is stymied due to public perceptions of risk.

Refusal to accept low dose radiation health interventions such as Xrays and cancer treatments, to rejection of new innovative technologies, such as small modular nuclear reactors, are but a few examples of the spectrum of uncertainty, unknowns and nonsense that result from the public’s perceptions surrounding LDR. 

A collaborative interactive session at the Canadian Science and Policy Conference will tackle the wicked problem of risk and policymaking, focusing specifically on perceptions of low dose radiation in relation to medical treatments and new innovative technologies such as small modular nuclear reactors. Questions concern how risks are understood, characterized, and constructed by the public and participants of the session will be explored. What about Indigenous knowledge and worldviews? How can expert-based organizations better grapple with and understand the role of values in shaping the public’s perception of LDR?  How can and should the linear no threshold assumption in relation to LDR be modified? Can a better understanding of value differences help shape policies about acceptable risk thresholds and appropriate strategies for communicating and mitigating risk?