Fundamentals of wildlife dosimetry and lessons learned from a decade of measuring external dose rates in the field.

Methods for determining the radiation dose received by exposed biota require major improvements to reduce uncertainties and increase precision. We share our experiences in attempting to quantify external dose rates to free-ranging wildlife using GPS-coupled dosimetry methods. The manuscript is a primer on fundamental concepts in wildlife dosimetry in which the complexities of quantifying dose rates are highlighted, and lessons learned are presented based on research with wild boar and snakes at Fukushima, wolves at Chornobyl, and reindeer in Norway.

The impact of sampling scale: A comparison of methods for estimating external contaminant exposure in free-ranging wildlife.

The impacts of contaminants on wildlife are dose dependent, and thus being able to track or predict exposure following contamination events is important for monitoring ecosystem health. However, the ability to track exposure in free-ranging wildlife is often severely limited. Consequently, researchers have predominantly relied on simple methods for estimating contaminant exposures in wildlife with little regard for spatial contaminant heterogeneity or an animal's use of diverse habitats.

Plant-plant interaction by Aster leiophyllus affects herbivory by Sika deer, Cervus nippon.

Changes in leaf traits in response to plant-plant interactions affect feeding by insect herbivores. However, the effects of such changes on feeding by vertebrate herbivores remain unclear. We examined the effects of interactions of Aster leiophyllus collected in the field (growing with plants of the same species [aggregated] or with plants of different species [solitary]) or grown in pots (with another A.

Increased abundance of a common scavenger affects allocation of carrion but not efficiency of carcass removal in the Fukushima Exclusion Zone.

The 2011 nuclear accident in Fukushima, Japan caused the evacuation of > 100,000 people and prompted studies on environmental impacts of radiological contamination. However, few researchers have explored how the human evacuation has affected ecosystem processes. Despite contamination, one common scavenger (wild boar, Sus scrofa) is 2-3× more abundant inside the Fukushima Exclusion Zone (FEZ).

Radiocesium accumulation and germline mutations in chronically exposed wild boar from Fukushima, with radiation doses to human consumers of contaminated meat.

Genetic effects and radioactive contamination of large mammals, including wild boar (Sus scrofa), have been studied in Japan because of dispersal of radionuclides from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Such studies have generally demonstrated a declining trend in measured radiocesium body burdens in wildlife. Estimating radiation exposure to wildlife is important to understand possible long-term impacts.

Evaluation of DNA damage and stress in wildlife chronically exposed to low-dose, low-dose rate radiation from the Fukushima Dai-ichi Nuclear Power Plant accident.

The health effects associated with chronic low-dose, low-dose rate (LD-LDR) exposures to environmental radiation are uncertain. All dose-effect studies conducted outside controlled laboratory conditions are challenged by inherent complexities of ecological systems and difficulties quantifying dose to free-ranging organisms in natural environments. Consequently, the effects of chronic LD-LDR radiation exposures on wildlife health remain poorly understood and much debated.

Differentiating Fukushima and Nagasaki plutonium from global fallout using Pu/Pu atom ratios: Pu vs. Cs uptake and dose to biota.

Plutonium (Pu) has been released in Japan by two very different types of nuclear events - the 2011 Fukushima accident and the 1945 detonation of a Pu-core weapon at Nagasaki. Here we report on the use of Accelerator Mass Spectrometry (AMS) methods to distinguish the FDNPP-accident and Nagasaki-detonation Pu from worldwide fallout in soils and biota. The FDNPP-Pu was distinct in local environmental samples through the use of highly sensitive Pu/Pu atom ratios.

Effects of chronic low-dose radiation on cataract prevalence and characterization in wild boar (Sus scrofa) from Fukushima, Japan.

This study evaluated cataracts in wild boar exposed to chronic low-dose radiation. We examined wild boar from within and outside the Fukushima Exclusion Zone for nuclear, cortical, and posterior subcapsular (PSC) cataracts in vivo and photographically. Plausible upper-bound, lifetime radiation dose for each boar was estimated from radioactivity levels in each animal's home range combined with tissue concentrations of Cesium.

Mating of escaped domestic pigs with wild boar and possibility of their offspring migration after the Fukushima Daiichi Nuclear Power Plant accident.

The 2011 Tohoku earthquake drastically changed human activities in some regions of Fukushima Prefecture, Japan. The subsequent tsunami damage and radioactive pollution from the Fukushima Daiichi nuclear power plant resulted in the evacuation of humans, and abandonment of agricultural lands, allowing population expansion of wildlife into areas formally inhabited by domesticated livestock. Unintentional escape of domesticated pigs into wildlife inhabited environments also occurred.

A comparison of methods to derive aggregated transfer factors using wild boar data from the Fukushima Prefecture.

Aggregated transfer factors (T; m kg) are often used to predict radionuclide activity concentrations in biota (Bq kg) from soil contamination levels (Bq m). Inherently large uncertainties in T values severely limit their predictive power. Many published T values have been derived from radionuclide deposition onto soil following weapons fallout, or the accidents at Chernobyl and Fukushima.

Gene expression analyses of the small intestine of pigs in the ex-evacuation zone of the Fukushima Daiichi Nuclear Power Plant.

Background: After the accident at the Fukushima Daiichi Nuclear Power Plant, radioactive contaminants were released over a widespread area. Monitoring the biological effects of radiation exposure in animals in the ex-evacuation zone should be continued to understand the health effects of radiation exposure in humans. The present study aimed to clarify the effects of radiation by investigating whether there is any alteration in the morphology and gene expressions of immune molecules in the intestine of pigs and inobuta (wild boar and domestic pig hybrid) in the ex-evacuation zone in 2012.