Risk management decisions in public health require consideration of a number of complex, often conflicting factors. The aim of this review was to propose a set of 10 fundamental principles to guide risk decision-making. Although each of these principles is sound in its own right, the guidance provided by different principles might lead the decision-maker in different directions. For example, where the precautionary principle advocates for preemptive risk management action under situations of scientific uncertainty and potentially catastrophic consequences, the principle of risk-based decision-making encourages decision-makers to focus on established and modifiable risks, where a return on the investment in risk management is all but guaranteed in the near term. To evaluate the applicability of the 10 principles in practice, one needs to consider 10 diverse risk issues of broad concern and explore which of these principles are most appropriate in different contexts. The 10 principles presented here afford substantive insight into the process of risk management decision-making, although decision-makers will ultimately need to exercise judgment in reaching appropriate risk decisions, accounting for all of the scientific and extra-scientific factors relevant to the risk decision at hand.

The NexGen framework published in Environmental Health Perspectives integrates three different views on the future of chemical risk assessment. The NexGen framework emulates a fundamental change towards in chemical testing for toxicity, as outlined 2007 NRC report, Toxicity Testing in the 21st Century: A Vision and a Strategy. This framework integrates population health approaches with chemical risk assessment methods, by integrating determinants of health into the risk assessment process. Additional perspective comes from the recommendations of the 2009 NRC report, Science and Decisions: Advancing Risk Assessment. The report also calls for changes within the risk assessment process, including the enhanced role of problem formulation, the unification of non-cancer and cancer methods for deriving dose-response relationships, and cumulative risk assessment. The integration of these three driving concepts is discussed in this review expanding the strengths of these three frameworks and what they brought to the NexGen framework for risk science.

One of the major challenges in chemical safety assessment is prioritisation of the large number of chemicals in commerce. Over the past five years, a new tiered approach to chemical safety assessment that uses margin of exposure (MOE) as the metric for determining the level of testing required, identifies chemicals of greatest concern. This paper evaluates the role of new technologies and novel tools in improving different steps of chemical risk assessment processes such as high throughput screening (HTS) in vitro assay platforms, high content biological omics assays, molecular biomarkers, quantitative structure activity relationship (QSAR) modelling, in vitro to in vivo extrapolation (IVIVE) and physiologically-based pharmacokinetic (PBPK) modelling. Other technologies such as functional genomics, bioinformatics, and computational biology can expedite the analysis. This new approach could potentially be used to prioritise and categorise chemicals on the domestic substance list (DSL) under the Canadian Environmental Protection Act (CEPA).

The publication of the US National Academy of Sciences report Toxicity Testing in the Twenty-First Century: A Vision and a Strategy (TT21C) has led to the development of new scientific techniques to modernise regulatory toxicity testing. From 2009 to 2010, a series of five international symposia were held to examine challenges, opportunities and policy issues associated with TT21C. Seven key themes emerged based on these meetings; that the TT21C vision and strategy: 1) is not self-implementing; 2) demands new toxicology techniques; 3) has a number of scientific knowledge gaps that need to be filled; 4) requires evaluation of the new tests to determine relevance, reliability, validity and regulatory acceptance by government agencies; 5) can be implemented under TSCA and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) as currently written; 6) requires multi-stakeholder input and commitment; 7) should harmonise acceptance of test data and methods on an international level.

This article summarises efforts at disease surveillance and risk management of chronic wasting disease (CWD). CWD is a fatal neurodegenerative disease of cervids and is considered to be one of the most contagious of the transmissible spongiform encephalopathies (TSEs). Evidence has demonstrated a strong species barrier to CWD for both human and farm animals other than cervids. CWD is now endemic in many US states and two Canadian provinces. Past management strategies of selective culling, herd reduction, and hunter surveillance have shown limited effectiveness. The initial strategy of disease eradication has been abandoned in favour of disease control. CWD continues to spread geographically in North American and risk management is complicated by the presence of the disease in both wild (free-ranging) and captive (farmed) cervid populations. The article concludes that further evaluation by risk managers is required for optimal, cost-effective strategies for aggressive disease control.

The evaluation and regulation of chemical substances have undergone a major overhaul in Canada, the USA and the European Union (EU) over the last decade. To facilitate increasing concerns over chemical safety, changes in regulations and strategic plans were introduced. Specifically, the Canadian parliament adopted a new amendment to the Canadian Environmental Protection Act (CEPA) in 1999, the US National Academy of Sciences published the 2007 NRC report TT21C, the US EPA developed the Strategic Plan in 2009, and the EU introduced new legislation in 2007 called Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH substances). A 2013 workshop held in Ottawa (Risk Sciences International) focused on regulatory issues and challenges faced by these nations. This review summarises many of the discussions held during the workshop and specifically, five challenges that Canada has encountered when assessing chemicals with limited data on Canada's Domestic Substances List (DSL).

ABSTARCTChronic wasting disease (CWD) is a neurodegenerative, protein misfolding disease affecting cervids in North America in epidemic proportions. While the existence of CWD has been known for more than 40 years, risk management efforts to date have not been able to curtail the spread of this condition. An expert elicitation exercise was carried out in May 2011 to obtain the views of international experts on both the etiology of CWD and possible CWD risk management strategies. This study presents the results of the following three components of the elicitation exercise: (1) expert views of the most likely scenarios for the evolution of the CWD among cervid populations in Canada, (2) ranking analyses of the importance of direct and indirect transmission routes, and (3) rating analyses of CWD control measures in farmed and wild cervids. The implications of these findings for the development of CWD risk management strategies are described in a Canadian context.

A high degree of uncertainty exists for chronic wasting disease (CWD) transmission factors in farmed and wild cervids. Evaluating the factors is important as it helps to inform future risk management strategies. Expert opinion is often used to assist decision making in a number of health, science, and technology domains where data may be sparse or missing. Using the Classical Model of elicitation, a group of experts was asked to estimate the most likely values for several risk factors affecting CWD transmission. The formalized expert elicitation helped structure the issues and hence provide a rational basis for estimating some transmission risk factors for which evidence is lacking. Considered judgments regarding environmental transmission, latency of CWD transmission, management, and species barrier were provided by the experts. Uncertainties for many items were determined to be large, highlighting areas requiring more research. The elicited values may be used as surrogate values until research evidence becomes available.

OBJECTIVES: In 2011, the U.S. Environmental Protection Agency initiated the NexGen project to develop a new paradigm for the next generation of risk science.METHODS: The NexGen framework was built on three cornerstones: the availability of new data on toxicity pathways made possible by fundamental advances in basic biology and toxicological science, the incorporation of a population health perspective that recognizes that most adverse health outcomes involve multiple determinants, and a renewed focus on new risk assessment methodologies designed to better inform risk management decision making.RESULTS: The NexGen framework has three phases. Phase I (objectives) focuses on problem formulation and scoping, taking into account the risk context and the range of available risk management decision-making options. Phase II (risk assessment) seeks to identify critical toxicity pathway perturbations using new toxicity testing tools and technologies, and to better characterize risks and uncertainties using advanced risk assessment methodologies. Phase III (risk management) involves the development of evidence-based population health risk management strategies of a regulatory, economic, advisory, community-based, or technological nature, using sound principles of risk management decision making.CONCLUSIONS: Analysis of a series of case study prototypes indicated that many aspects of the NexGen framework are already beginning to be adopted in practice.

BACKGROUND Low-molecular-weight heparin (LMWH) is cleared predominantly by the kidneys and hence there is uncertainty about the safety of its use in hemodialysis (HD) patients. Our primary objective was to compare whether tinzaparin and dalteparin differentially accumulate in HD patients. STUDY DESIGN Open-label randomized controlled trial. SETTING & PARTICIPANTS HD patients undergoing periprocedure bridging anticoagulation. INTERVENTION After warfarin therapy was discontinued, participants were randomly assigned to either 3 daily doses of tinzaparin (175 IU/kg) or dalteparin (200 IU/kg), with 2 intervening HD treatments between the first dose of study drug and their procedure. OUTCOMES The primary outcome was predialysis anti-Xa levels 20 to 24 hours after the third LMWH dose (therapeutic target, <0.2 IU/mL). Secondary outcomes included thromboembolic events and major bleeding. RESULTS Of 29 eligible and consenting patients, 17 patients received tinzaparin and 12 patients received dalteparin. Mean predialysis anti-Xa level 20-24 hours after the third LMWH dose was 0.37 ± 0.23 (SD) IU/mL for tinzaparin and 0.62 ± 0.41 IU/mL for dalteparin (P = 0.1), indicating clinically important accumulation for both drugs. No invasive procedures were canceled due to study drug accumulation. 4 patients experienced serious adverse events (1 major bleed after traumatic arteriovenous fistula puncture in the tinzaparin arm, 2 non-ST-elevation myocardial infarctions [1 in each group], and 1 upper-extremity deep venous thrombosis [dalteparin group]). LIMITATIONS Small sample size. CONCLUSIONS Dalteparin and tinzaparin significantly accumulate in HD patients at therapeutic doses. "Bridging therapy" with LMWHs at therapeutic doses in HD patients who require temporary interruption of warfarin therapy has the potential for complications and is of uncertain benefit. Other anticoagulation strategies, including no bridging therapy or intravenous heparin, need comparative evaluation in this unique patient population.

In 2007, the U.S. National Research Council (NRC) published a groundbreaking report entitled Toxicity Testing in the 21st Century: A Vision and a Strategy. The purpose of this report was to develop a long-range strategic plan to update and advance the way environmental agents are tested for toxicity. The vision focused on the identification of critical perturbations of toxicity pathways that lead to adverse human health outcomes using modern scientific tools and technologies. This review describes how emerging scientific methods will move the NRC vision forward and improve the manner in which the potential health risks associated with exposure to environmental agents are assessed. The new paradigm for toxicity testing is compatible with the widely used four-stage risk assessment framework originally proposed by the NRC in 1983 in the so-called Red Book. The Nrf2 antioxidant pathway provides a detailed example of how relevant pathway perturbations will be identified within the context of the new NRC vision for the future of toxicity testing. The implications of the NRC vision for toxicity testing for regulatory risk assessment are also discussed.

In 2007, the U.S. National Research Council (NRC) released a report, "Toxicity Testing in the 21st Century: A Vision and a Strategy," that proposes a paradigm shift for toxicity testing of environmental agents. The vision is based on the notion that exposure to environmental agents leads to adverse health outcomes through the perturbation of toxicity pathways that are operative in humans. Implementation of the NRC vision will involve a fundamental change in the assessment of toxicity of environmental agents, moving away from adverse health outcomes observed in experimental animals to the identification of critical perturbations of toxicity pathways. Pathway perturbations will be identified using in vitro assays and quantified for dose response using methods in computational toxicology and other recent scientific advances in basic biology. Implementation of the NRC vision will require a major research effort, not unlike that required to successfully map the human genome, extending over 10 to 20 years, involving the broad scientific community to map important toxicity pathways operative in humans. This article provides an overview of the scientific tools and technologies that will form the core of the NRC vision for toxicity testing. Of particular importance will be the development of rapidly performed in vitro screening assays using human cells and cell lines or human tissue surrogates to efficiently identify environmental agents producing critical pathway perturbations. In addition to the overview of the NRC vision, this study documents the reaction by a number of stakeholder groups since 2007, including the scientific, risk assessment, regulatory, and animal welfare communities.

Abstract Abstract 3136 Poster Board III-73 Background Low-molecular-weight heparins (LMWHs) can be administered in fixed subcutaneous doses permitting predictable parenteral anticoagulation in an out-of-hospital setting. The renal clearance of LMWHs leads to uncertainty about the safety of use of LMWHs in patients on hemodialysis given the potential for bioaccumulation of anticoagulant effect which may lead to bleeding. Methods We conducted a randomized open label trial to investigate the feasibility and safety of a perioperative anticoagulation protocol in hemodialysis patients comparing two LMWHs preparations as outpatient bridging therapy when warfarin is interrupted for invasive procedures. The primary objective of the study was to compare if tinzaparin and dalteparin differentially bioaccumulate in hemodialysis (HD) patients after three therapeutic doses. Warfarin therapy was discontinued in these patients 5 to 6 days prior to surgery. Patients were randomized to either 3 doses of tinzaparin (175 IU/kg/day) or dalteparin (200 IU/kg/day) with two dialyses in the interval between the first dose of study drug and inavsive procedure. Primary outcome was pre-dialysis anti-Xa levels 20-24hrs post third therapeutic LMWH dose to determine if these LMWHs accumulated in HD patients, and if they differentially accumulated. After procedure, patients received a daily prophylactic dose of tinzaparin (4500 IU) and dalteparin (5000 IU) for 3 to 4 days along with dialysis. Post- procedure pre- and post- dialysis anti-Xa levels were also monitored. Results Of 29 eligible and consenting patients, 17 patients (58.6%) received tinzaparin sodium and 12 patients (41.4%) received dalteparin sodium. Two patients were withdrawn prior to invasive procedure and the invasive procedures were canceled (1 for important bio-accumulation in the dalteparin arm; 1 for major bleed in the tinzaparin arm). Primary outcome anti-Xa samples were not analyzable in 2 patients (1 contaminated with heparin; 1 drawn too early). There was important and significant bioaccumulation in both study drug arms. The mean primary outcome pre-dialysis anti-Xa level 20-24hrs post third tinzaparin dose was 0.40 IU/ml (SD= 0.21). The mean primary outcome pre-dialysis anti-Xa level 20-24hrs post third dalteparin dose was 0.57 IU/ml (SD= 0.43). There was no statistically significant difference between the two study drug groups (student's t-test (p value = 0.33). Postoperatively 16/21 (76%) of patients tested had undetectable pre-dialysis anti-Xa levels 20-24hrs post prophylactic dose, with the remaining 5 patients having a mean anti-Xa level of 0.23 IU/ml (SD = 0.25). During subsequent follow-up, 2 patients experienced serious adverse events (one non-STEMI in patient who died of sepsis (tinzaparin group) and one upper extremity DVT (dalteparin group)). Conclusions Tinzaparin and Dalteparin significantly accumulate at therapeutic doses in HD patients with no statistically significant difference detected in accumulation between the drugs. Neither drug importantly accumulates at prophylactic doses in HD patients. “Bridging therapy” with LMWHs at therapeutic doses in patients on hemodialysis who require temporary interruption of warfarin for invasive procedures is risky and of uncertain risk benefit. Disclosures Rodger: Bayer: Research Funding; Leo Pharma: Research Funding; Pfizer: Research Funding; Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees; Biomerieux: Research Funding; GTC Therapeutics: Research Funding.