Exploring Biological Effects of Low Level Radiation From the Other Side of Background

The REPAIR Project: Examining the Biological Impacts of Sub-Background Radiation Exposure within SNOLAB, a Deep Underground Laboratory

“…All research to date has utilized either single celled organisms (4-11, 17, 19, 20) or in vitro cell culture models (9,10,(12)(13)(14)(15)(16)18), and the observed results may not translate to the whole organism level. Animal work in underground facilities such as SNOLAB is hampered by space limitations and restrictions in laboratory access, which makes many species, such as murine models, extremely difficult to work with.…”

“…Biological experiments have also been conducted within the Waste Isolation Pilot Plant (WIPP), a nuclear waste repository in New Mexico. However, at a depth of 650 m, WIPP has considerably less shielding compared to SNOLAB or LNGS and only reduces background dose rates by a factor of 15 (9).…”

Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

“…In our first study, we compared the growth of D. radiodurans at underground vs. aboveground laboratories and observed that cultures shielded from background radiation grew slower in a 48 h growth period (Smith et al, 2011). Later on as we included S. oneidensis in our experiments, we also moved our background control underground (current setting), simulating a background radiation dose with 11.5 kg of KCl (5 uCi of 40 K) to create an energy field with a target dose rate of 100 nGy hr −1 (average US background from gamma sources, Figure 1C).…”

“…Could such a reaction be defined as a stress response? We propose that research on the biological responses to reduced-radiation environments, "from the other side of background" (Smith et al, 2011), can yield unique information that will inform both the underlying science and policy applications of radiation protection. It is necessary to consider that natural background radiation is made up of both low and high LET (Linear Energy Transfer) sources and that the latter tend to have stronger biological effects (Goodhead, 1999).…”

“…The first evidence of a deleterious biological response to radiation doses lower than background was reported by Planel et al (1987), who observed a longer generation time in Paramecium tetraurelia and a lower cell number in Synechococcus lividus cultures when these organisms were grown shielded from radiation at dose rates 17 and 6 times lower than background, respectively. Since then, experiments with other organisms have shown similar deleterious effects when exposed to below background levels of radiation, such as lower protection to mutational damage in Saccharomyces cerevisiae (Satta et al, 1995); higher sensitivity to apoptosis, higher intracellular concentration of oxidative stressrelated enzymes, and higher mutation rate induced by gamma rays (after conditioning under below background conditions) in Cricetulus griseus (Satta et al, 2002); growth rate retardation in Mus musculus L5178Y cells (Kawanishi et al, 2012), changes in the concentration of oxidative stress-related enzymes (Fratini et al, 2015), and lower cell number and/or up regulation of DNA repair and oxidative stress genes in Shewanella oneidensis and Deinococcus radiodurans (Smith et al, 2011;Castillo et al, 2015).…”