Integration of ecosystem science into radioecology: A consensus perspective.

In the Fall of 2016 a workshop was held which brought together over 50 scientists from the ecological and radiological fields to discuss feasibility and challenges of reintegrating ecosystem science into radioecology. There is a growing desire to incorporate attributes of ecosystem science into radiological risk assessment and radioecological research more generally, fueled by recent advances in quantification of emergent ecosystem attributes and the desire to accurately reflect impacts of radiological stressors upon ecosystem function. This paper is a synthesis of the discussions and consensus of the workshop participant's responses to three primary questions, which were: 1) How can ecosystem science support radiological risk assessment? 2) What ecosystem level endpoints potentially could be used for radiological risk assessment? and 3) What inference strategies and associated methods would be most appropriate to assess the effects of radionuclides on ecosystem structure and function? The consensus of the participants was that ecosystem science can and should support radiological risk assessment through the incorporation of quantitative metrics that reflect ecosystem functions which are sensitive to radiological contaminants. The participants also agreed that many such endpoints exit or are thought to exit and while many are used in ecological risk assessment currently, additional data need to be collected that link the causal mechanisms of radiological exposure to these endpoints. Finally, the participants agreed that radiological risk assessments must be designed and informed by rigorous statistical frameworks capable of revealing the causal inference tying radiological exposure to the endpoints selected for measurement.

The tubercular badger and the uncertain curve:- The need for a multiple stressor approach in environmental radiation protection.

This article presents the results of a workshop held in Stirling, Scotland in June 2018, called to examine critically the effects of low-dose ionising radiation on the ecosphere. The meeting brought together participants from the fields of low- and high-dose radiobiology and those working in radioecology to discuss the effects that low doses of radiation have on non-human biota. In particular, the shape of the low-dose response relationship and the extent to which the effects of low-dose and chronic exposure may be predicted from high dose rate exposures were discussed. It was concluded that high dose effects were not predictive of low dose effects. It followed that the tools presently available were deemed insufficient to reliably predict risk of low dose exposures in ecosystems. The workshop participants agreed on three major recommendations for a path forward. First, as treating radiation as a single or unique stressor was considered insufficient, the development of a multidisciplinary approach is suggested to address key concerns about multiple stressors in the ecosphere. Second, agreed definitions are needed to deal with the multiplicity of factors determining outcome to low dose exposures as a term can have different meanings in different disciplines. Third, appropriate tools need to be developed to deal with the different time, space and organisation level scales. These recommendations permit a more accurate picture of prospective risks.

When a duck is not a duck; a new interdisciplinary synthesis for environmental radiation protection.

This consensus paper presents the results of a workshop held in Essen, Germany in September 2017, called to examine critically the current approach to radiological environmental protection. The meeting brought together participants from the field of low dose radiobiology and those working in radioecology. Both groups have a common aim of identifying radiation exposures and protecting populations and individuals from harmful effects of ionising radiation exposure, but rarely work closely together. A key question in radiobiology is to understand mechanisms triggered by low doses or dose rates, leading to adverse outcomes of individuals while in radioecology a key objective is to recognise when harm is occurring at the level of the ecosystem. The discussion provided a total of six strategic recommendations which would help to address these questions.

The need to integrate laboratory- and ecosystem-level research for assessment of the ecological impact of radiation.

Despite the fact that the Chernobyl and Fukushima accidents have both stimulated research on the environmental impact of radiation, interpretations about the occurrence of ecological effects in the contaminated areas still do not converge. In an effort to improve the situation and progress toward better general scientific understanding of ecological impacts of radiation, reasons that may explain the disagreements and discrepancies are explored. The divergence in interpretations of the impacts from both nuclear accidents arises from differences in methodological and conceptual inference strategies (a cultural issue) more so than fundamental differences in the processes governing ecological harm. Improved integration of scientific communities that use different study approaches should be encouraged to better understand and monitor the determination of the ecological impacts of radiation. Integr Environ Assess Manag 2016;12:673-676. © 2016 SETAC.

Addressing ecological effects of radiation on populations and ecosystems to improve protection of the environment against radiation: Agreed statements from a Consensus Symposium.

This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters' accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks. Scientific research conducted in a variety of laboratory and field settings has improved our knowledge of the effects of ionizing radiation on the environment. However, the results from such studies sometimes appear contradictory and there is disagreement about the implications for risk assessment. The Symposium discussions therefore focused on issues that might lead to different interpretations of the results, such as laboratory versus field approaches, organism versus population and ecosystemic inference strategies, dose estimation approaches and their significance under chronic exposure conditions. The participating scientists, from across the spectrum of disciplines and research areas, extending also beyond the traditional radioecology community, successfully developed a constructive spirit directed at understanding discrepancies. From the discussions, the group has derived seven consensus statements related to environmental protection against radiation, which are supplemented with some recommendations. Each of these statements is contextualized and discussed in view of contributing to the orientation and integration of future research, the results of which should yield better consensus on the ecological impact of radiation and consolidate suitable approaches for efficient radiological protection of the environment.

Using an Ecosystem Approach to complement protection schemes based on organism-level endpoints.

Radiation protection goals for ecological resources are focussed on ecological structures and functions at population-, community-, and ecosystem-levels. The current approach to radiation safety for non-human biota relies on organism-level endpoints, and as such is not aligned with the stated overarching protection goals of international agencies. Exposure to stressors can trigger non-linear changes in ecosystem structure and function that cannot be predicted from effects on individual organisms. From the ecological sciences, we know that important interactive dynamics related to such emergent properties determine the flows of goods and services in ecological systems that human societies rely upon. A previous Task Group of the IUR (International Union of Radioecology) has presented the rationale for adding an Ecosystem Approach to the suite of tools available to manage radiation safety. In this paper, we summarize the arguments for an Ecosystem Approach and identify next steps and challenges ahead pertaining to developing and implementing a practical Ecosystem Approach to complement organism-level endpoints currently used in radiation safety.

Radiation-induced risks at low dose: moving beyond controversy towards a new vision.

The paper recently published by Mothersill and Seymour (Radiat Environ Biophys 2013, doi: 10.1007/s00411-013-0472-y ) is commented upon by emphasizing on the recommendation not to confound the fields of radiation protection and radiobiological science as a source of controversy. Instead, these authors are proposing a new vision which suggests novel lines of scientific investigations to be addressed. At the moment, these include moving beyond the conceptual approach of DNA alteration through energy deposition in cells, and exploring the striking parallel currently existing between the ongoing individual/population debate in radioecology and that for cells/tissues in radiobiology. These interesting issues are briefly discussed and supported.

Technology and the forces of nature: a lesson of humility calling for ecocentrism.

The incident at the Fukushima Daiichi nuclear power plant, resulting from the powerful earthquake and tsunami that struck the northeastern coast of Japan in March 2011, reminds humankind of the powerful natural forces that shape our world. This article calls for a new ecocentric approach to human interaction with the environment, with particular reference to the environmental consequences of radiation.

Recommendations from the International Union of Radioecology to improve guidance on radiation protection.

This brief commentary summarizes the views of a working group assembled by the International Union of Radioecology to advance the approaches used to evaluate effects of radioactive materials in the environment. The key message in both the research needs and the recommendations for management of radioactive materials centers around the need to adopt an ecocentric approach that recognizes the interconnectedness of biota, including humans, and ecological processes.

Plant uptake of radiocaesium from artificially contaminated soil monoliths covering major European soil types.

Uptake of (137)Cs was measured in different agricultural plant species (beans, lettuce, barley and ryegrass) grown in 5 undisturbed soil monoliths covering major European soil types. The first cultivation was made three years after soil contamination and plants were grown during 3 successive years. The plant-soil (137)Cs transfer factors varied maximally 12-fold among soils and 35-fold among species when grown on the same soil. Single correlations between transfer factors and soil properties were found, but they varied widely with plant type and can hardly be used as a predictive tool because of the few soils used. The variation of (137)Cs concentrations in plants among soils was related to differences in soil solution (137)Cs and K concentrations, consistent with previous observations in hydroponics and pot trials. Absolute values of transfer factors could not be predicted based on a model validated for pot trials. The (137)Cs activity concentration in soil solution decreased significantly (11- to 250-fold) for most soils in the 1997-1999 period and is partly explained by decreasing K in soil solution. Transfer factors of lettuce showed both increasing and decreasing trends between 2 consecutive years depending on soil type. The trends could be explained by the variation in (137)Cs and K concentrations in soil solution. It is concluded that differences in (137)Cs transfer factors among soils and trends in transfer factors as a function of time can be explained from soil solution composition, as shown previously for pot trials, although absolute values of transfer factors could not be predicted.

The ecological relevance of current approaches for environmental protection from exposure to ionising radiation.

This paper discusses the current approaches to environmental protection from ionising radiation from an ecological perspective, highlighting the need to understand fully what we are trying to protect. Ecologically relevant endpoints for environmental protection are discussed along with the need to integrate protection from ionising radiation with the approaches adopted for non-radioactive contaminants. A possible integrated assessment approach is outlined.

Protection of the environment: how to position radioprotection in an ecological risk assessment perspective.

The development of a system capable of ensuring adequate protection of the environment from the harmful effects of ionising radiation is at present particularly debated. This need comes both from a restrictive consideration of the environment in the so far existing system for human radioprotection, and the planetary-wide growing concerns about man's technogenic influence on his environment which have yielded 'sustainability' and 'precaution' as guiding principles for environmental protection. Whilst evolving from the field of human radioprotection, the radioprotection of the environment needs to be discussed in a wider perspective, with particular emphasis on the most advanced concepts which emerge from the efforts to deriving improved approaches to Ecological Risk Assessment. For the sake of protection, the environment is traditionally addressed through its biota since these are the sensitive components of ecosystems. Similarities between man and biotas reflect the ubiquitous mechanistic effects of radiation on life which disrupt molecules. However, important differences also arise in a number of perspectives, from the large spectrum of different species of biotas to their hierarchical self-organisation as interacting populations within ecosystems. Altogether, these aspects are prone to promote complex arrays of different responses to stress which lie beyond the scope of human radioprotection due to its focus on individuals of a single species. By means of selected illustrations, this paper reviews and discusses the current challenges faced in proper identification of measurable effect endpoints (stochastic/deterministic, individual/population- or ecosystem-relevant), dose limits in chronic exposure (or levels of concern), and their consideration according to radiation type (RBE) and interactions with other contaminants (synergies/antagonisms) which represent critical gaps in knowledge. The system of human radioprotection has conceptually been targeted at limiting cancer induction (stochastic) in human individuals, whereas the current approach in radioprotection of biota targets reproductive success (deterministic) and cytogenetic effects, thought to have the highest significance at population and ecosystem levels. The focus on individuals in a bottom-up approach, due to the ease with which it may be quantified, has prompted the development of current ecotoxicological methods as a scientific foundation for environmental protection regulation. However, the most recent ecological theories, which emphasise on complex systems as a key to modern ecological understanding, call for the additional consideration of more holistic, top-down, approaches. Critically, dose-effect relationships of the subsystem components may lose their predictive ability at the system level.