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LaKind J.S.,LaKind Associates LLC | LaKind J.S.,University of Maryland, Baltimore | Naiman D.Q.,Johns Hopkins University | Hays S.M.,Summit Toxicology | And 2 more authors.
Journal of Exposure Science and Environmental Epidemiology | Year: 2010

Trihalomethanes (THMs) can form as byproducts during drinking water disinfection, which is crucial for limiting human exposure to disease-causing pathogens. The US Environmental Protection Agency (USEPA), recognizing both the importance of water disinfection for public health protection and potential risks associated with THM exposure, developed disinfection byproduct rules with the parallel goals of ensuring safe drinking water and limiting the levels of THMs in public water systems. The National Health and Nutrition Examination Survey (NHANES) THM blood data can be used as a means for assessing US population exposures to THMs; biomonitoring equivalents (BEs) can provide human health risk-based context to those data. In this paper, we examine the blood THM levels in the 1999-2004 NHANES data to (i) determine weighted population percentiles of blood THMs, (ii) explore whether gender and/or age are associated with blood THM levels, (iii) determine whether temporal trends can be discerned over the 6-year timeframe, and (iv) draw comparisons between population THM blood levels and BEs. A statistically significant decrease in blood chloroform levels was observed across the 1999-2004 time period. Age-related differences in blood chloroform levels were not consistent and no gender-related differences in blood chloroform levels were observed. The concentrations of all four THMs in the blood of US residents from the 2003 to 2004 NHANES dataset are below BEs consistent with the current US EPA reference doses. For bromodichloromethane and dibromochloromethane, the measured median blood concentrations in the United States are within the BEs for the 10 -6 and 10 -4 cancer risk range, whereas measured values for bromoform generally fall below the 10 -6 cancer risk range. These assessments indicate that general population blood concentrations of THMs are in a range considered to be a low to medium priority for risk assessment follow-up, according to the guidelines for interpretation of biomonitoring data using BEs. © 2010 Nature Publishing Group All rights reserved. Source

Heffernan A.L.,University of Queensland | Aylward L.L.,Summit Toxicology LLP | Toms L.-M.L.,Queensland University of Technology | Sly P.D.,University of Queensland | And 2 more authors.
Journal of Exposure Science and Environmental Epidemiology | Year: 2014

Biomonitoring has become the "gold standard" in assessing chemical exposures, and has an important role in risk assessment. The pooling of biological specimens - combining multiple individual specimens into a single sample - can be used in biomonitoring studies to monitor levels of exposure and identify exposure trends or to identify susceptible populations in a cost-effective manner. Pooled samples provide an estimate of central tendency and may also reveal information about variation within the population. The development of a pooling strategy requires careful consideration of the type and number of samples collected, the number of pools required and the number of specimens to combine per pool in order to maximise the type and robustness of the data. Creative pooling strategies can be used to explore exposure-outcome associations, and extrapolation from other larger studies can be useful in identifying elevated exposures in specific individuals. The use of pooled specimens is advantageous as it saves significantly on analytical costs, may reduce the time and resources required for recruitment and, in certain circumstances, allows quantification of samples approaching the limit of detection. In addition, the use of pooled samples can provide population estimates while avoiding ethical difficulties that may be associated with reporting individual results.© 2014 Nature America, Inc. Source

Maier A.,University of Cincinnati | Ovesen J.L.,University of Cincinnati | Allen C.L.,University of Cincinnati | York R.G.,RG York and Associates LLC | And 4 more authors.
Regulatory Toxicology and Pharmacology | Year: 2015

Ethanol-based topical antiseptic hand rubs, commonly referred to as alcohol-based hand sanitizers (ABHS), are routinely used as the standard of care to reduce the presence of viable bacteria on the skin and are an important element of infection control procedures in the healthcare industry. There are no reported indications of safety concerns associated with the use of these products in the workplace. However, the prevalence of such alcohol-based products in healthcare facilities and safety questions raised by the U.S. FDA led us to assess the potential for developmental toxicity under relevant product-use scenarios. Estimates from a physiologically based pharmacokinetic modeling approach suggest that occupational use of alcohol-based topical antiseptics in the healthcare industry can generate low, detectable concentrations of ethanol in blood. This unintended systemic dose probably reflects contributions from both dermal absorption and inhalation of volatilized product. The resulting internal dose is low, even under hypothetical, worst case intensive use assumptions. A significant margin of exposure (MOE) exists compared to demonstrated effect levels for developmental toxicity under worst case use scenarios, and the MOE is even more significant for typical anticipated occupational use patterns. The estimated internal doses of ethanol from topical application of alcohol-based hand sanitizers are also in the range of those associated with consumption of non-alcoholic beverages (i.e., non-alcoholic beer, flavored water, and orange juice), which are considered safe for consumers. Additionally, the estimated internal doses associated with expected exposure scenarios are below or in the range of the expected internal doses associated with the current occupational exposure limit for ethanol set by the Occupational Safety and Health Administration. These results support the conclusion that there is no significant risk of developmental or reproductive toxicity from repeated occupational exposures and high frequency use of ABHSs or surgical scrubs. Overall, the data support the conclusion that alcohol-based hand sanitizer products are safe for their intended use in hand hygiene as a critical infection prevention strategy in healthcare settings. © 2015 The Authors. Source

Aylward L.L.,Summit Toxicology LLP | Aylward L.L.,University of Queensland | Green E.,Statistics Canada | Porta M.,Autonomous University of Barcelona | And 9 more authors.
Environment International | Year: 2014

Background: Australian national biomonitoring for persistent organic pollutants (POPs) relies upon age-specific pooled serum samples to characterize central tendencies of concentrations but does not provide estimates of upper bound concentrations. This analysis compares population variation from biomonitoring datasets from the US, Canada, Germany, Spain, and Belgium to identify and test patterns potentially useful for estimating population upper bound reference values for the Australian population. Methods: Arithmetic means and the ratio of the 95th percentile to the arithmetic mean (P95:mean) were assessed by survey for defined age subgroups for three polychlorinated biphenyls (PCBs 138, 153, and 180), hexachlorobenzene (HCB), p,p-dichlorodiphenyldichloroethylene (DDE), 2,2',4,4' tetrabrominated diphenylether (PBDE 47), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Results: Arithmetic mean concentrations of each analyte varied widely across surveys and age groups. However, P95:mean ratios differed to a limited extent, with no systematic variation across ages. The average P95:mean ratios were 2.2 for the three PCBs and HCB; 3.0 for DDE; 2.0 and 2.3 for PFOA and PFOS, respectively. The P95:mean ratio for PBDE 47 was more variable among age groups, ranging from 2.7 to 4.8. The average P95:mean ratios accurately estimated age group-specific P95s in the Flemish Environmental Health Survey II and were used to estimate the P95s for the Australian population by age group from the pooled biomonitoring data. Conclusions: Similar population variation patterns for POPs were observed across multiple surveys, even when absolute concentrations differed widely. These patterns can be used to estimate population upper bounds when only pooled sampling data are available. © 2014 Elsevier Ltd. Source

Beck N.B.,American Chemistry Council | Becker R.A.,American Chemistry Council | Erraguntla N.,Texas Commission on Environmental Quality | Farland W.H.,Colorado State University | And 14 more authors.
Environment International | Year: 2016

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. © 2016 The Authors. Source

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