Fate of Nitroglycerin and Dinitrotoluene in Soil at Small Arms Training Ranges

Nitroglycerine (NG), 2-4-dinitrotoluene, and 2,6-dinitrotolune (DNTs), commonly deposited on soil during military training, have been identified as potential threats to groundwater at Camp Edwards on the Massachusetts Military Reservation. Accordingly, a series of experiments were performed to obtain site-specific sorption coefficients (K_d) for use in computer simulations. Experiments employing aqueous, reagent-grade contaminants, with a biocide added, showed NG underwent limited sorption onto the sandy soil from the study area. DNTs were retained to a greater extent. Desorption experiments demonstrated a portion of the contaminants were irreversibly bound. Soil characteristics had a significant effect on K_d, apparently because of changes in organic carbon, cation exchange capacity, and/or clay content with depth in the soil profile. Experiments with NG containing soil, fresh, unfired propellant, or with freshly fired propellant produced partitioning values considerably higher than those observed with reagent grade material added from solution—demonstrating dissolution as the rate-limiting step. The apparent K_d also increased significantly when no biocide was used, thereby indicating a major role for biodegradation. In addition, NG and the DNTs introduced during military training did not leach from site soil at the small arms ranges studied. Taken together these data demonstrate that K_ds from laboratory experiments using dissolved reagent-grade compounds are not appropriate for predicting NG and DNT mobility in the field.     

Reevaluation of Phosphate as a Means of Retarding Lead Transport from Sandy Firing Ranges

Phosphate has become an accepted remediation strategy to immobilize lead on firing ranges. In some cases, however, phosphate treatment has been reported to increase lead concentrations in field water leaching tests. The present study evaluated the influence of phosphate (sodium phosphate, PO_4(aq), or particulate hydroxyapatite, HA) and lead (lead nitrate, Pb_(aq), or particulate lead oxide, PbO_(s)) sources on the physical, chemical, and relative transport properties of their reaction products. Relative transport behavior of the product of each of the four possible combinations was investigated with settling columns assessing potential surface water transport and sand columns assessing potential ground water transport. Pyromorphite (HYP) was the only product formed when PO_4(aq) and Pb_(aq) were combined. The HYP formed under these conditions was the least mobile form of lead and phosphate examined in this work. Although additional products were formed when PO_4(aq) was combined with PbO_(s), lead transport was significantly reduced compared to the PbO control. On the other hand, HA was much less effective at controlling the transport of Pb_(aq) in sand columns, particularly at low pH. In addition, the presence of HA increased the mobility of PbO at pH 7.2 relative to the control. It is recommended that the accepted practice of using HA in sandy firing range soils, under low to neutral pH conditions, be reconsidered.     

Human Health Risk Assessment of a Civilian-Accessible Active Firing Range

The Korean Federation of Teachers Association, the Korea Ministry of Education, Science and Technology, and the Korea Ministry of National Defense (KMND) concluded a memorandum of understanding (MOU) on opening military sites to elementary, middle, and high school students to strengthen national security consciousness. According to the MOU, the KMND decided to open an active firing range; however, due to the ongoing firing activity, site contamination by toxic energetic materials (EMs) was suspected. To identify whether opening the firing range might pose a human health threat to the students and their teachers visiting the site, we conducted a risk assessment to evaluate potential risk. The risk assessment results revealed that both cancer risk and non-cancer risk were negligible. The potential cancer risk was in the range of 1.9 × 10^–11 and 1.4 × 10^–10, and the potential non-cancer hazard index was in the range of 2.3 × 10^–6 and 4.9 × 10^–6.     

Speciation and Vertical Distribution of Lead and Lead Shot in Soil at a Recreational Firing Range

In this study, the speciation, vertical distribution and soil particle size fractions of lead in soil samples at a recreational firing range was determined. This study was performed to gain a better understanding of how lead shot breaks down at ranges. Both the chemical form of lead and the types of soil particles with which lead is associated are important for understanding not only the mobility and persistence, but also the human and ecological impact of lead at these ranges. Lead as shot gun pellets was found to be the dominant form of lead in soil samples. The highest levels were measured in surface samples located in the “fall zone” of the range. Results indicate shot to be relatively absent below surficial samples. Lead concentrations in soil decreased markedly across a 0–6″ depth profile. Lead carbonates were the dominant non-shot form of lead present at all depths. Water-soluble lead species made up a minor fraction of the non-shot lead present in the samples. Based on soil particle sizes measured, highest concentrations of lead were measured in soil particles passing a 0.075 mm sieve.     

Application of a Probabilistic Risk Assessment Methodology to a Lead Smelter Site

Exposure of children to lead in the environment was assessed at the Murray Smelter Superfund site using both a deterministic risk assessment approach, the Integrated Exposure Uptake Biokinetic (IEUBK) model, and a probabilistic approach, the Integrated Stochastic Exposure (ISE) model. When site-specific data on lead in environmental media were input as point estimates into the IEUBK model, unacceptable risks were predicted for children living within five of eight study zones. The predicted soil cleanup goal was 550?ppm. Concentration and exposure data were then input into the ISE model as probability distribution functions and a one-dimensional Monte Carlo analysis (ID MCA) was run to predict the expected distribution of exposures and blood lead values. Uncertainty surrounding these predictions was examined in a two-dimensional Monte Carlo analysis (2-D MCA). The ISE model predicted risks that were in the same rank order as those predicted by the IEUBK model, although the probability estimates of exceeding a blood lead level of 10?µg/dl (referred to as the P10) from the ISE model were uniformly lower than those predicted by the IEUBK model. The 2-D MCA allowed evaluation of the confidence around each P10 level, and identified the main sources of both uncertainty and variability in exposure estimates. The ISE model suggested cleanup goals ranging from 1300 to 1500 ppm might be protective at this site.     

Health Risk Assessment of Lead in the Republic of Korea

The purpose of this study was to estimate the daily exposure to lead due to food ingestion, air inhalation, and soil ingestion in the Republic of Korea's general population, and to evaluate the level of risk associated with the current lead exposure level using the proportional daily dose (3–4 μg/kg body weight/day) corresponding to the Provisional Tolerable Weekly Intake (PTWI) suggested by the Joint FAO/WHO Expert Committee on Food Additives as the toxicological tolerance level. The estimation of the daily exposure to lead via three pathways including food, soil ingestion and air inhalation was conducted as a chronic exposure assessment. For the lead exposure assessment through dietary intake, 1,389 lead residue data for 45 commodities investigated by the Korea Food and Drug Administration during the period 1995–2000 were utilized (KFDA 1996, 1997, 1998). Six hundred seventy-two air monitoring data from 7 major cities during the period 1993–2000 and 4,500 soil residue data at 1,500 sites during the period 1999–2001 were considered for the lead exposure assessment involving air inhalation and soil ingestion, respectively. The total daily exposure to lead was estimated by combining dietary intake, inhaled amount and soil intake corresponding to the typical activity of the general population, which was treated as a group of adults with a body weight of 60 kg. For risk characterization, the daily exposure to lead was compared with the toxicological tolerance level. The level of risk due to lead exposure was calculated using the hazard ratio (HR). The dietary intake of lead was 9.71 × 10_?4 mg/kg/day and the total daily exposure level, including air inhalation and soil ingestion, was 9.97 × 10_?4 mg/kg/day. The exposure contributions of foods, air and soil induced from the percentage of each media to the total daily exposure were 97.4%, 2.1% and 0.5%, respectively. Of the different commodity groups, the highest contribution to the total exposure came from grain, which represented 47.7% of the total. Additional exposure to lead occurs in certain population groups due to the use of tobacco, alcoholic beverages, and the intake of other foods, all factors not considered in this study. Through the comparison of the daily exposure to lead with the tolerance level based on the PTWI, the hazard ratio was estimated as being 0.25–0.33. This value implies that no increase in blood lead level is to be expected in the general population at the current lead exposure levels.     

Pore Water Quality in the Upper Part of the Vadose Zone under an Operating Canadian Small Arms Firing Range Backstop Berm

Canadian military small arms firing range (SAFR) backstop berm soils contain high concentrations of Pb, Cu, Sb, and Zn. Three Teflon® cylindrical lysimeters were installed in the vadose zone of the backstop berm in order to characterize the pore water quality. Copper-Zn concentrations were below their respective Québec drinking water thresholds, and Pb-Sb concentrations were above the criteria in many cases, indicating that a metal vertical migration occurs in the vadose zone. Metal concentrations in pore water were, in decreasing order, Zn > Pb > Sb > Cu. Calculated annual metal leaching rates showed that a rather small portion of the metals in the soil were mobilized in the vadose zone, and that metals were a potential source of contamination for extremely long periods of time, highlighting the importance of finding ways to remediate such soils in order to limit metal mobility in SAFR backstop berms.     

Risk Assessment as a Decision-Making Tool for Treatment of Emissions at a New Aluminum Smelter in Iceland: 2. Human Health Risk Assessment

Alcoa recently constructed the Fjarðaál aluminum smelter in Reyðarfjörður, East Iceland. The smelter is designed to produce a maximum of 346,000 metric tons per year of aluminum. A risk assessment was conducted to evaluate the differential human health risk related to estimated potential air emissions from the planned Fjarðaál smelter with and without seawater scrubbers. Air-dispersion modeling results provided for particulate matter (PM₁₀), sulfur dioxide (SO₂), hydrogen fluoride (HF), and polycyclic aromatic hydrocarbons (PAHs) were compared to ambient air standards or air quality guidelines from Norway, Iceland, or European directives and from the U.S. Environmental Protection Agency. Risk estimates were calculated for PAHs. Modeled air estimates were mapped geospatially, to identify potential receptors, including onsite outdoor worker, seagoing worker, hypothetical fence-line resident, future hypothetical resident, closest current resident, residents in neighboring villages, closest farmer, and a visitor to the nearby Holmanes Nature Reserve. Both with and without seawater scrubbers, the predicted exceedances of standards per year for SO₂ were well below the maximum number allowed. Use of seawater scrubbers was predicted to decrease average SO₂ air concentration estimates in the short term; however, annual estimates were lower without seawater scrubbers. Risk estimates for carcinogenic and non-carcinogenic PAHs, and modeled air concentrations of HF and PM₁₀, were well within acceptable levels.     

Human Health Risk Assessment at a Depleted Uranium Site

Human health risk assessments for depleted uranium are common for Department of Defense (DOD) sites since the metal has various military uses. At a training and experimental site, DU was evaluated in soil in order to make decisions regarding cleanup and future use of the site. At this site, concentrations were found to be protective of human health; DU is less toxic than uranium. Other data important to this decision were the type of receptors likely to be exposed, the amount of time spent by the receptor on-site, the acceptable yearly radiation dose, and other non-radiation associated effects to the kidney. Total uranium concentrations in soil were calculated for the 90th percentile and the 50th percentile. The highest soil concentration used as an exposure point was 3500 ug/g (90th percentile). Short exposure timeframes contributed to the risk results.     

Assessment of Predictive Habitat Models for Bighorn Sheep in California's Peninsular Ranges

ABSTRACT We developed predictive habitat models for a bighorn sheep (Ovis Canadensis) population in the Peninsular Ranges of southern California, USA, using 2 Geographic Information System modeling techniques, Ecological Niche Factor Analysis (ENFA) and Genetic Algorithm for Rule-set Production (GARP). We used >16,000 Global Positioning System locations from 34 animals in 5 subpopulations to develop and test ENFA and GARP models, and we then compared these models to each other and to the expert-based model presented in the United States Fish and Wildlife Service's Recovery Plan for this population. Based on a suite of evaluation methods, we found both ENFA and GARP to provide useful predictions of habitat; however, models developed with GARP appeared to have higher predictive power. Habitat delineations resulting from GARP models were similar to the expert-based model, affirming that the expert-based model provided a useful delineation of bighorn sheep habitat in the Peninsular Ranges. In addition, all 3 models identified continuous bighorn sheep habitat from the northern to southern extent of our study area, indicating that the Recovery Plan's recommendation of maintaining habitat connectivity throughout the range is an appropriate goal.     

Risk Assessment as a Decision-Making Tool for Treatment of Emissions at a New Aluminum Smelter in Iceland: 3. Ecological Assessment

Predictive ecological risk assessment was used to determine whether any risk-reduction benefit would result from the installation and operation of wet scrubbers at an aluminum smelter in East Iceland. Sulfur dioxide and hydrogen fluoride exposure will not result in any appreciable risk to mosses, lichens, lodgepole pine, and heather/heath grassland communities beyond the dilution zone without scrubbers. With scrubbers, exceedances of plant criteria may occur beyond the dilution zone. Critical concentrations of polycyclic aromatic hydrocarbons (PAHs) and hydrogen fluoride (HF) in terrestrial wildlife food items were converted to critical air concentrations, which were then compared to modeled air concentrations. Terrestrial wildlife species are not expected to be exposed to PAH concentrations that result in appreciable risk. If wildlife species are assumed to consume only grasses, predicted HF exposures will not result in exceedance of toxicity thresholds. However, if wildlife species are assumed to consume only heather, thresholds are exceeded at some locations for the rock ptarmigan and wood mouse. Results of population modeling indicate no potential for population impacts to rock ptarmigan outside the facility boundary. Impacts to wood mouse carrying capacity are expected to extend beyond the dilution zone with scrubbers, but not without.     

Development of a Wearable Framework for the Assessment of a Mechanical-Based Indicator of Falling Risk in the Field

ObjectivesThe characterization of the instability of gait is a current challenge of biomechanics. Indeed, risks of falling naturally result from the difficulty to control perturbations of the locomotion pattern. Hence, the assessment of a synthetic parameter able to quantify the instability in real time will be useful for the prevention of falls occurring in this context. Thus, the objective of the present study, in two steps, was to propose and evaluate a relevant parameter to quantify the risk of fallings.Material and MethodsExperimental analysis of the gait of 11 able-bodied subjects from a motion capture system in laboratory condition was performed. The distance of the Body Center of Mass (BCOM) to the Minimal Moment Axis (MMA) was computed as a proxy of whole-body angular momentum variations. In a second step, we quantified the kinematics during gait with wearable Inertial Measurement Units (IMU) fixed on two individuals (one able bodied person and one person with transfemoral amputation). We compared the IMU-based BCOM kinematics with a motion capture reference system to verify the accuracy of our measures in the field.ResultsNormative thresholds of the distance of the Body Center of Mass (BCOM) to the Minimal Moment Axis (MMA) during able-bodied level walking were assessed. The average error between the BCoM displacement computed from the IMU and from the reference vicon data of 4 mm, 3 mm and 53 mm on the mediolateral, anteroposterior and vertical axes respectively.ConclusionAll these results make it possible to consider the determination of the risks of falls in the field at mid-term. the research on an optimal configuration that maintain the performance while simplifying the device will be essential to make it acceptable by the individuals.     

Development and Internal Validation of a Predictive Model for Individual Cancer Risk Assessment for Thyroid Nodules

Objective: The objective of this study was to develop and validate a predictive model for the assessment of the individual risk of malignancy of thyroid nodules based on clinical, ultrasound, and analytic variables.Methods: A retrospective case-control study was carried out with 542 patients whose thyroid nodules were analyzed at our endocrinology department between 2013 and 2018 while undergoing treatment for thyroidectomy. Starting with a multivariate logistic regression analysis, which included clinical, analytic, and ultrasound variables, a predictive model for thyroid cancer (TC) risk was devised. This was then subjected to a cross-validation process, using resampling techniques.Results: In the final model, the independent predictors of the risk of malignancy were: being male, age of the extremes, family history of TC, thyroid-stimulating hormone level >4.7 μU/L, presence of autoimmune thyroiditis, solid consistency, hypoechogenicity, irregular or microlobed borders, nodules that are taller than they are wide, microcalcifications, and suspicious adenopathy. With a cut-off point of 50% probability of thyroid cancer, the predictive model had an area under the receiver operating characteristic curve of 0.925 (95% confidence interval 0.898 to 0.952). Finally, using the 10-fold cross-validation method, the accuracy of the model was found to be 88.46%, with a kappa correlation coefficient of 0.62.Conclusion: A predictive model for the individual risk of malignancy of thyroid nodules was developed and validated using clinical, analytic, and ultrasound variables. An online calculator was developed from this model to be used by clinicians to improve decision-making in patients with thyroid nodules.     

Development of a Relative Ranking Risk Index for Risk Assessment in the Transportation of Liquefied Petroleum Gas in Mexico City's Metropolitan Area

The development of a relative ranking methodology created specifically for the assessment of the risk due transportation of Liquefied Petroleum Gas (LPG) in Mexico City is reported. Mexico City has a number of conditions that present specific challenges: Large population, varied geography, large consumption of LPG, and all sorts of vehicles, including those for LPG. Given Mexico's status as “emerging economy,” it is reasonable to assume that the main causes that promote accidents during transportation of LPG are quite different from those in developed countries. This issue was corroborated through information from official sources and from news media. Due to the lack of official data, a systematic collection of information on the media was performed. A relative ranking methodology was developed based on a systematic study to elucidate the main causes of accidents in Mexico and on the results derived from the integrated database from official data and the media. The weighting that made up the Risk Index for Transportation of LPG is based on the same database. A classification guide was created in order to harmonize criteria in the assessment of the parameters of the proposed risk index.     

Gene-Gene Interactions Lead to Higher Risk for Development of Type 2 Diabetes in an Ashkenazi Jewish Population

Background

Evidence has accumulated that multiple genetic and environmental factors play important roles in determining susceptibility to type 2 diabetes (T2D). Although variants from candidate genes have become prime targets for genetic analysis, few studies have considered their interplay. Our goal was to evaluate interactions among SNPs within genes frequently identified as associated with T2D.

Methods/Principal Findings

Logistic regression was used to study interactions among 4 SNPs, one each from HNF4A[rs1884613], TCF7L2[rs12255372], WFS1[rs10010131], and KCNJ11[rs5219] in a case-control Ashkenazi sample of 974 diabetic subjects and 896 controls. Nonparametric multifactor dimensionality reduction (MDR) and generalized MDR (GMDR) were used to confirm findings from the logistic regression analysis. HNF4A and WFS1 SNPs were associated with T2D in logistic regression analyses [P<0.0001, P<0.0002, respectively]. Interaction between these SNPs were also strong using parametric or nonparametric methods: the unadjusted odds of being affected with T2D was 3 times greater in subjects with the HNF4A and WFS1 risk alleles than those without either (95% CI = [1.7–5.3]; P≤0.0001). Although the univariate association between the TCF7L2 SNP and T2D was relatively modest [P = 0.02], when paired with the HNF4A SNP, the OR for subjects with risk alleles in both SNPs was 2.4 [95% CI = 1.7–3.4; P≤0.0001]. The KCNJ11 variant reached significance only when paired with either the HNF4A or WFSI SNPs: unadjusted ORs were 2.0 [95% CI = 1.4–2.8; P≤0.0001] and 2.3 [95% CI = 1.2-4.4; P≤0.0001], respectively. MDR and GMDR results were consistent with the parametric findings.

Conclusions

These results provide evidence of strong independent associations between T2D and SNPs in HNF4A and WFS1 and their interaction in our Ashkenazi sample. We also observed an interaction in the nonparametric analysis between the HNF4A and KCNJ11 SNPs (P≤0.001), demonstrating that an independently non-significant variant may interact with another variant resulting in an increased disease risk.     

Landscape Ecotoxicology and Assessment of Risk at Multiple Scales

Traditional approaches to ecotoxicology and ecological risk assessment frequently have ignored the complexities arising due to the spatial heterogeneity of natural systems. In recent years, however, ecologists have become increasingly aware of the influence of spatial organization on ecological processes. Landscape ecology provides a conceptual and theoretical framework for the analysis of spatial patterns, the characterization of spatial aspects of ecosystem function, and the understanding of landscape dynamics. Incorporating the insights of landscape ecology into ecotoxicology will enhance our ability to understand and ultimately predict the effects of toxic substances in ecological systems. Ecological risk assessments need to explicitly consider multiple spatial scales, accounting for heterogeneity within contaminated areas and for the larger landscape context. A simple simulation model is presented to illustrate the effects of spatial heterogeneity by linking an individual-based toxicokinetic model with a spatially distributed metapopulation model. Dispersal of organisms between contaminated and uncontaminated patches creates a situation where risk analysis must consider a spatial extent broader than the toxicant-contaminated area. In general, the addition of a toxicant to a source patch (i.e., a net exporter of individuals) will have a greater impact than the same toxicant addition to a sink patch (i.e., a net importer of individuals).     

Trends in the Development of Ecological Risk Assessment and Management Frameworks

Ecological risk assessment and management have grown from a long history of assessment and management activities aimed at improving the everyday lives of humans. The background against which ecological risk assessment and management has developed is discussed and recent trends in the development of risk assessment and management frameworks documented. Seven frameworks from five different countries are examined. All maintain an important role for science, suggest adaptive approaches to decision-making and have well-defined analytical steps. Differences in approaches toward the separation of policy and science, the preference for management over assessment, the inclusion of stakeholders, the iterative nature of the analytical cycle, the use of decision criteria and economic information suggest considerable evolution in framework design over time. Despite the changes, no consensus on the design of a framework is apparent and work remains to be done on refining an integrative framework that effectively incorporates both policy and science considerations for environmental management purposes.