Single point estimates of human health hazard/toxicity values such as a reference dose (RfD) are generally used in chemical hazard and risk assessment programs for assessing potential risks associated with site- or use-specific exposures. The resulting point estimates are often used by risk managers for regulatory decision-making, including standard setting, determination of emission controls, and mitigation of exposures to chemical substances. Risk managers, as well as stakeholders (interested and affected parties), often have limited information regarding assumptions and uncertainty factors in numerical estimates of both hazards and risks. Further, the use of different approaches for addressing uncertainty, which vary in transparency, can lead to a lack of confidence in the scientific underpinning of regulatory decision-making. The overarching goal of this paper, which was developed from an invited participant workshop, is to offer five approaches for presenting toxicity values in a transparent manner in order to improve the understanding, consideration, and informed use of uncertainty by risk assessors, risk managers, and stakeholders. The five approaches for improving the presentation and communication of uncertainty are described using U.S. Environmental Protection Agency's (EPA's) Integrated Risk Information System (IRIS) as a case study. These approaches will ensure transparency in the documentation, development, and use of toxicity values at EPA, the Agency for Toxic Substances and Disease Registry (ATSDR), and other similar assessment programs in the public and private sector. Further empirical testing will help to inform the approaches that will work best for specific audiences and situations.

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"The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gatherng mnd maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden to Department of Defense, Washington Headquarters Services Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display s currently valid OMB control number. 12. DISTRIBUTIONIAVAILABILITY STATEMENT Approved for public release; distribution unlimited. PLEASE DO NOT SUPPLEMENTARY NOTES14. ABSTRACT A Human Effectiveness and Risk Characterization for Electromuscular Incapacitation (EMI) reflects the results from three workshops (data gathering/sharing, peer consultation, and independent external review) evaluating two EMI devices: the M26 and X26 TASERs. The intended effect of these devices is electromuscular disruption. Key potential unintended effects included ocular injury, seizures, ventricular fibrillation, or fall injuries. The likelihood of these effects were determined, based on an analysis of the TASER International Database (scrubbed to minimize false positives) and modeling. The probability of inducing a complete EMD ranges from 74% to 52% depending on distance to the target. Probability estimates were up to 0.04% for eye "strikes and 0.15% for fall injuries depending on distance to the target. Ventricular fibrillation (VF) is not expected to occur in an otherwise healthy adult population. Key data gaps include the biological basis for TASER effects and appropriate dosimetry. The results support the conclusion that the M26 and X26 TASERs are generally effective for their intended use. SUBJECT TERMS ABSTRACTA Human Effectiveness and Risk Characterization (HERC) for Electromuscular Incapacitation (EMI; also referred to as Electromuscular Disruption (EMD) when describing the intended effect of the TASER® products) devices has been conducted in an effort organized by the Human Effects Center of Excellence (HECOE). This HERC reflects the results from a three-workshop process with sequential workshops held for data gathering and sharing, peer consultation, and independent external review of the HERC document. This HERC included two EMI devices manufactured by TASER International, the M26 and X26 TASERs®.Probability estimates as well as data gaps and uncertainties were characterized for intended and potential unintended effects of the devices. The intended effect of the TASER is electromuscular disruption. During EMD, the individual experiences tetany and is temporarily incapacitated. Key potential unintended effects tha...

1,4-Dioxane is found in consumer products and is used as a solvent in manufacturing. Studies in rodents show liver tumors to be consistently reported after chronic oral exposure. However, there were differences in the reporting of non-neoplastic lesions in the livers of rats and mice. In order to clarify these differences, a reread of mouse liver slides from the 1978 NCI bioassay on 1,4-dioxane in drinking water was conducted. This reread clearly identified dose-related non-neoplastic changes in the liver; specifically, a dose-related increase in the hypertrophic response of hepatocytes, followed by necrosis, inflammation and hyperplastic hepatocellular foci. 1,4-Dioxane does not cause point mutations, DNA repair, or initiation. However, it appears to promote tumors and stimulate DNA synthesis. Using EPA Guidelines (2005), the weight of the evidence suggests that 1,4-dioxane causes liver tumors in rats and mice through cytotoxicity followed by regenerative hyperplasia. Specific key events in this mode of action are identified. A Reference Dose (RfD) of 0.05mg/kgday is proposed to protect against regenerative liver hyperplasia based on a benchmark dose (BMD) approach. Based on this RfD, a maximum contaminant level goal of 350μg/L is proposed using a default relative source contribution for water of 20%.

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