[Show abstract][Hide abstract] ABSTRACT: Shale gas exploration and production (E&P) has experienced substantial growth across the U.S. over the last decade. The Barnett Shale, in north-central Texas, contains one of the largest, most active onshore gas fields in North America, stretching across 5000square miles and having an estimated 15,870 producing wells as of 2011. Given that these operations may occur in relatively close proximity to populated/urban areas, concerns have been expressed about potential impacts on human health. In response to these concerns, the Texas Commission on Environmental Quality established an extensive air monitoring network in the region. This network provides a unique data set for evaluating the potential impact of shale gas E&P activities on human health. As such, the objective of this study was to evaluate community-wide exposures to volatile organic compounds (VOCs) in the Barnett Shale region. In this current study, more than 4.6million data points (representing data from seven monitors at six locations, up to 105 VOCs/monitor, and periods of record dating back to 2000) were evaluated. Measured air concentrations were compared to federal and state health-based air comparison values (HBACVs) to assess potential acute and chronic health effects. None of the measured VOC concentrations exceeded applicable acute HBACVs. Only one chemical (1,2-dibromoethane) exceeded its applicable chronic HBACV, but it is not known to be associated with shale gas production activities. Annual average concentrations were also evaluated in deterministic and probabilistic risk assessments and all risks/hazards were below levels of concern. The analyses demonstrate that, for the extensive number of VOCs measured, shale gas production activities have not resulted in community-wide exposures to those VOCs at levels that would pose a health concern. With the high density of active wells in this region, these findings may be useful for understanding potential health risks in other shale play regions.
Full-text · Article · Sep 2013 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: The Lower Passaic River (LPR) is one of the most heavily industrialized waterways in the US with both historical and continuing discharges of chemicals from point and non-point sources. Significant efforts have been initiated on behalf of public, private, and regulatory entities to restore this degraded urban river. Considerable attention has been devoted to characterizing environmental media with respect to human and ecological risk. As part of these efforts, a wealth of environmental data have been collected and analyzed for a variety of metals, pesticides, organic compounds, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzodioxins/furans (PCDD/Fs), and dioxin-like compounds. The objectives of the study described in this paper were two-fold: (1) to generate LPR-specific data for use in human health risk assessment by characterizing concentrations of contaminants in LPR fish tissue samples based on publicly available data using a methodical and transparent approach, and (2) using the resulting data, to calculate the contaminant concentrations in a "Representative Fish," which is a representation of proportional fish tissue concentrations calculated based upon consumption patterns of LPR anglers. The data reduction, processing, and analyses described provide a representative dataset for the conduct of a human health assessment associated with fish consumption from the LPR.
[Show abstract][Hide abstract] ABSTRACT: Buchanan et al. assert that our recent fish ingestion risk assessment for a section of the Lower Passaic River (LPR) (Urban et al., 2009a) utilizes inappropriate ingestion rates and is inconsistent with state and USEPA guidelines and risk assessment procedures, and therefore underestimates the human health risks associated with angler exposure along this stretch of the river. However, they fail to support these assertions with evidence; indeed, in a recent response to similar allegations, we demonstrated that the utilized ingestion rates are, in fact, the most appropriate for this parameter (Urban et al., 2009b). Our reliance on data from a comprehensive, independently validated, peer-reviewed, and site-specific creel angler survey (CAS) in order to define fish and crab ingestion rates for this region of the LPR is fully compliant with USPEA guidelines. In fact, the crab ingestion survey and risk assessment cited by Buchanan et al. as evidence of crabbing activity and crab ingestion for this region was less comprehensive than the CAS in question, was not overseen by an independent panel, has yet to be peer-reviewed, and does not provide any activity or consumption data for this section of the LPR. Contrary to the implications of Buchanan et al., our effort provides a transparent, comprehensive, and scientifically legitimate human health risk assessment of fish ingestion for the lowest 6miles of the LPR. Thus we adamantly disagree with the characterization and assertions put forth by Buchanan et al., and stand by the conclusions presented in Urban et al. (2009a) and defended in Urban et al. (2009b).
No preview · Article · Feb 2010 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Mugdan et al. have criticized certain aspects of the approach and general conclusions of our recently published fish ingestion risk assessment for the lower Passaic River (Urban et al., 2009), asserting that they are inconsistent with the United States Environmental Protection Agency's risk assessment guidelines we reference in our paper. Specifically, they assert that the excess cancer risk and health hazard results calculated as a part of our analyses underestimate the potential health risk posed to lower Passaic River anglers who actually consume their catch due to the fish ingestion rates we utilized in our analysis and our lack of inclusion of a crab ingestion pathway. While there clearly are differences between our risk assessment and the one conducted by the USEPA, this is not at all surprising given that their assessment reflects a typical screening-level risk assessment while that described in our paper reflects a more detailed site-specific risk assessment. In developing our exposure scenarios and assumptions, we considered and incorporated the available site-specific information in both deterministic and probabilistic quantitative risk frameworks in an effort to provide a sound and realistic human health risk assessment that quantitatively accounts for much of the variability and uncertainty typically inherent in such estimates. Although it is understandable that Mugdan et al. are compelled to defend the effort and conclusions put forth by USEPA Region 2 in its 2007 draft human health risk assessment of the lower Passaic River, the site-specific lower Passaic River human health risk assessment presented in Urban et al. (2009) was conducted according to USEPA guidelines, underwent peer review, and is, in fact, consistent with Superfund guidance and accepted principles of risk assessment.
No preview · Article · Nov 2009 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: The Lower Passaic River (LPR) in New Jersey has been impacted by variety of human activities over the course of the last two centuries. In this risk assessment, we assessed potential human health risks associated with consumption of fish from the LPR, the human exposure pathway of greatest concern when addressing contaminated sediments. Our risk assessment incorporates fish consumption information gathered during a year-long, intercept-style creel angler survey and representative fish tissue concentrations for 156 chemicals of potential concern (COPCs) obtained from USEPA's public database (OurPassaic website: http://www.ourpassaic.org/projectsites/premis_public/index.cfm?fuseaction=contaminants). Due to the large number of COPCs investigated, this risk assessment was divided into two phases: (1) identification of COPCs that contribute to the majority of overall excess cancer risk and hazard estimates using deterministic and probabilistic methods, and (2) probabilistic characterization of risk using distributions of chemical concentration and cooking loss for those compounds identified in Phase 1. Phase 1 relied on point estimates of COPC concentrations and demonstrated that PCDD/Fs and PCBs (dioxin-like and non-dioxin-like) are the greatest contributors to cancer risk, while non-dioxin-like PCBs are the primary contributors to non-cancer hazard estimates. Total excess cancer risks for adult and child and receptors estimated in Phase 1 were within USEPA's acceptable excess cancer risk range, with the exception of RME child (3.0 x 10(-4) and 1.3 x 10(-4) for deterministic and probabilistic approaches, respectively). Phase 2 focused on PCDD, PCDF, and PCBs and used distributions of chemical concentrations in fish. The results showed that all excess cancer risk estimates were within the acceptable risk range, although non-cancer hazard estimates for PCBs slightly exceeded a Hazard Index of 1. This HHRA of LPR fish ingestion represents the most comprehensive evaluation conducted to date, and demonstrates that measured concentrations of COPCs are not likely to pose a health risk to people who currently consume fish from the LPR.
No preview · Article · May 2009 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: A recent study by the U.S. Food and Drug Administration (FDA) indicated that some beverages contained benzene at levels above the federal drinking water standard of 5 parts per billion (ppb). In tests conducted by the FDA, Crystal Light Sunrise Classic Orange (CLSCO) was reported to contain benzene levels as high as 87.9 ppb. The purpose of the present study was to better characterize benzene concentrations in CLSCO and to quantify potential human health risks. Twenty-eight samples of CLSCO were obtained from retail stores in Houston, Tex., U.S.A. The mean benzene concentrations in 16 oz original and new formulation bottles were 90 and 0.18 ppb, respectively, while 64-oz bottles contained an average of 3.38 ppb. A variety of exposure scenarios were evaluated to determine potential health risks using both deterministic and probabilistic techniques. In the deterministic analyses, upper bound point estimate cancer risks ranged from 5.4E-6 to 8.7E-8, while hazard indices (HI) ranged from 0.28 to 0.00104. Probabilistic analyses were conducted to develop more realistic cancer risk estimates. In these analyses, the 50th and 95th percentile cancer risk estimates were 3.7E-6 and 8.0E-6, and the 50th and 95th percentile hazard indices were 0.19 and 0.42, respectively. In conclusion, all cancer risk estimates and noncancer hazards met the typical health risk benchmarks established by the U.S. regulatory agencies (1E-4 to 1E-6 for cancer and hazard indices less than 1.0).
No preview · Article · Jun 2008 · Journal of Food Science