A Quantitative Approach for Ranking Human Health Risks from Pesticides in Irish Groundwater

This study aims to quantitatively assess the risk of pesticides (used in Irish agriculture) and their degradation products to groundwater and human health. This assessment uses a human health Monte-Carlo risk-based approach that includes the leached quantity combined with an exposure estimate and the No Observed Adverse Effect Level (NOAEL) as a toxicity ranking endpoint, resulting in a chemical intake toxicity ratio statistic (R) for each pesticide. A total of 34 active substances and their metabolites registered and used in the agricultural field were evaluated. MCPA obtained the highest rank (i.e., in order of decreasing human health risk), followed by desethly-terbuthylazine and deethylatrazine (with risk ratio values of 1.1 × 10^?5, 9.5 × 10^?6, and 5.8 × 10^?6, respectively). A sensitivity analysis revealed that the soil organic carbon content and soil sorption coefficient were the most important parameters that affected model predictions (correlation coefficient of –0.60 and –0.58, respectively), highlighting the importance of soil and pesticide properties in influencing risk estimates. The analysis highlights the importance of taking a risk-based approach when assessing pesticide risk. The model can help to prioritize pesticides, with potentially negative human health effects, for monitoring programs as opposed to traditional approaches based on pesticide leaching potential.     

Potential of Soil and Groundwater Contamination Due to Mine Subsidence Under a Landfill

Results of a study to evaluate the effects of mine subsidence on the integrity of a clay liner and potential for soil and groundwater contamination below a previously mined landfill are presented. The results show that for the existing site conditions, surface subsidence features are expected to be similar to subsidence troughs, and the site has minimal potential of being contaminated due to deep-sited subsidence in the mine. To further reduce potential for soil and groundwater contamination at the site, it is recommended that the minimum thickness of the compacted clay liner be 4?ft instead of the 2 to 3?ft generally used. Discussion is presented indicating that further study is required to develop an adequate design procedure to determine the effects of nonuniform settlement of foundation soils or refuse on the hydraulic conductivity of landfill clay barriers.     

A Method for Assessing Environmental Risks of Oil-Mineral-Aggregate to Benthic Organisms

Previous studies have shown that Oil-Mineral-Aggregate (OMA) formation enhances the dispersion of marine oil spills, but the potential impacts of settled OMAs on benthic organisms are not well known. A comprehensive numerical approach is proposed here to model the transport of OMAs and assesses their potential risks. The predicted environmental concentrations (PEC) of settled oil in OMAs was calculated using a random walk particle tracking model and the benchmark concentrations (BCs) of individual hydrocarbon groups were computed based on a equilibrium partitioning (EqP) approach. The likely of risks in terms of Hazard Quotient (HQ) were then determined using a Monte Carlo simulation method. HQ for both aliphatic and aromatic hydrocarbon groups were calculated for OMAs formed with two sediments, Mississippi River Delta (MRD) and Standard Reference Material (SRM). Mean total HQs were also determined by a simple sum of individual HQ. The predicted results from a case study based on a spill of 1000 tons of South Louisiana crude oil in the Gulf of St. Lawrence with a water depth of 80 m show that the SRM is unlikely to cause adverse impacts but this may not be the case for MRD. Furthermore, it has been found that the application of chemical dispersant (CD) increased the risks of MRD but it had little effects on SRM.     

A Procedure for Life-Cycle-Based Solid Waste Management with Consideration of Uncertainty

The development of integrated solid-waste management (SWM) strategies that are efficient with respect to both cost and environmental performance is a complex task. It must incorporate the numerous interrelations among different unit operations in the solid waste system (e.g., collection, recycling, and combustion), and the large number of design parameters that affect estimates of cost and environmental emissions. Uncertainty in design and operational parameters can lead to uncertainty in the estimates of cost and emissions. This article describes an extension of the capability of the Integrated Solid Waste Management Decision Support Tool (ISWM DST) to enable consideration of the effects of uncertainty in input parameters. The uncertainty analysis capability is illustrated using a hypothetical case study of a typical municipality. Results show that increased expenditure does not necessarily result in a reduction in the expected levels of environmental emissions and that some SWM alternatives may be more robust, although deterministic estimates of their expected performances are similar. The uncertainty analysis also facilitates use of the ISWM DST by policy makers responsible for evaluation of the expected effect of SWM practices on, for example, greenhouse-gas emissions.     

Human Exposure to Malathion during a Possible Vector-Control Intervention against West Nile Virus. II: Evaluation of the Toxicological Risks Using a Probabilistic Approach

In order to prevent the propagation of West Nile Virus (WNV), insecticide sprayings have been carried out in several locations in North America since 1999 with the objective of controlling the mosquito populations that transmit this pathogen. An attempt to quantitatively compare the risk of developing a health response to WNV infection with the toxicological risk of insecticides is presented here. First, the acute and subchronic environmental concentrations resulting from repeated spraying events were modeled according to a reasonable worst-case spraying sequence established in an intervention program proposed by the Government of Quebec (Canada). Second, probability density functions (PDF) were established for some exposure parameters according to the data for the concerned population, when feasible. Monte Carlo analyses were performed by incorporating these PDF into the equations used to calculate the daily absorbed doses resulting from the exposure scenarios presented in the companion article (this issue). The results showed that for a significant proportion of the population, aerial and, to a lesser extent, ground sprayings of malathion can generate acute and subchronic exposure that may exceed some levels of toxicological concern based on the USEPA's reference values. Indeed, in the case of acute exposure following aerial spraying for infants, toddlers, and children, these proportions were respectively 37.1%, 59.5%, and 32.8% of the individuals, and 27.3%, 41.3%, and 24.9% following subchronic exposure. For ground spraying, these values were 12.5%, 24.2%, 8.8%; and 9.8%, 16.5%, and 7.4%. These results allowed the comparison of the probability of exceeding a level of toxicological concern for malathion exposure with the probability of developing WNV symptoms. This comparison shows that in some circumstances, the toxicological risk of malathion may exceed the infectious risk of WNV.     

Minimizing Environmental Risks Using Fuzzy TOPSIS: Location Selection for the ITU Faculty of Management

ABSTRACT

Environmental risk is a measure of potential threats to the environment and combines the probability that events will cause or lead to degradation of the environment and the severity of that degradation. Evaluation of environmental risk factors requires linguistic terms to be used rather than exact numerical assignments. The fuzzy set theory provides a useful tool for converting linguistic terms into numerical evaluations. In this article, we will try to select the best location for the Faculty of Management of the Istanbul Technical University taking care of the predetermined environmental criteria by using fuzzy TOPSIS. The decision matrix is composed of linguistic evaluations for the alternatives with respect to the environmental risk criteria. The Macka Campus area has been selected after the multicriteria evaluation. A sensitivity analysis is also realized to see if the minor changes in criteria weights cause any change in the ranking of alternatives. Unless the importance of the criteria rock or soil structure, remoteness to health facilities, transportation availability, and transportation costs is changed to be from low to extremely low importance, the Macka Campus is still the selected alternative.     

Monte Carlo Simulation-Based Health Risk Assessment of Heavy Metal Soil Pollution: A Case Study in the Qixia Mining Area,China

In recent years, heavy metal pollution accidents have occurred in many regions of China, and the public has become increasingly concerned about its health. Based on a U.S. Environmental Protection Agency model and using Monte Carlo simulation techniques, this article presents a procedure for health risk assessment of heavy metal pollution. A case study was conducted in the Qixia lead and zinc mining area. Based on the magnitude of heavy metal contamination in the mine factory, vicinal Qixia scenic site and village, the potential health risk calculated for a lifetime of exposure (through ingestion and dermal contact) was determined as the cumulative carcinogenic and non-carcinogenic risk for workers, tourists, and local residents (including children and adults), respectively. The risk assessment indicated that the carcinogenic risk is not significant. However, Pb poses a significant cumulative non-carcinogenic risk, which tends to be serious for workers. Additionally, local children are more vulnerable than adults to the risks associated with heavy metal contamination. Accordingly, risk alleviation and preventive measures should be taken, especially for children and workers.     

Analysis and Portrayal of Uncertainty in a Food-Web Exposure Model

The results of quantitative risk assessments are key factors in a risk manager's decision of the necessity to implement actions to reduce risk. The extent of the uncertainty in the assessment will play a large part in the degree of confidence a risk manager has in the reported significance and probability of a given risk. The two main sources of uncertainty in such risk assessments are variability and incertitude. In this paper we use two methods, a second-order two-dimensional Monte Carlo analysis and probability bounds analysis, to investigate the impact of both types of uncertainty on the results of a food-web exposure model. We demonstrate how the full extent of uncertainty in a risk estimate can be fully portrayed in a way that is useful to risk managers. We show that probability bounds analysis is a useful tool for identifying the parameters that contribute the most to uncertainty in a risk estimate and how it can be used to complement established practices in risk assessment. We conclude by promoting the use of probability analysis in conjunction with Monte Carlo analyses as a method for checking how plausible Monte Carlo results are in the full context of uncertainty.     

Risk Analysis Modeling of Production Costs and Occupational Health Exposure of Single‐Wall Carbon Nanotube Manufacturing

Considerable uncertainty exists about occupational risks, future environmental health and safety (EHS) standards, and associated production and compliance costs for single‐wall carbon nanotube (SWNT) manufacturing processes. We propose and illustrate the use of risk analysis Monte Carlo (MC) models to assess cost and exposure trade‐offs of the high‐pressure carbon monoxide (HiPco) SWNT manufacturing process given these uncertainties. Assumptions regarding the timing, frequency, magnitude, and expense of EHS standards are modeled as stochastic events and examined for their impact on the expected values, variances, and probability distributions of total production costs and occupational exposure. With a better understanding of associated risks, these models can help policy makers and manufacturers explore potential EHS benefits, consequences, and trade‐offs. For example, results suggest that voluntary implementation of a low level of protection (rather than none at all) can lead to reduced cost and exposure uncertainty with insignificant increases in production costs, as well as lowering total manufacturing and liability costs, depending on the assumptions made. Conversely, slower implementation rates of higher standards produce greater uncertainty in long‐term costs and exposure. More generally, the results of this study underscore three important observations: (1) Expected costs alone are insufficient for informed decision making; (2) the best level of standards, overall cost, and optimal voluntary standards are highly dependent on uncertain health effects; and (3) the resultant amount of uncertainty in total costs and exposure can be extreme.     

A Site-Specific Approach for the Evaluation of Natural Attenuation at Metals-Impacted Sites

Consideration of monitored natural attenuation (MNA) as a remedy component for metals-contaminated sites can be achieved using a site-specific screening approach, followed by application of one or a series of sequential extraction measurements. Hazardous waste sites contaminated with metals can be screened for the implementation of monitored natural attenuation on the basis of contaminant-specific soil chemical characteristics (i.e., K_d's, solubilities, and nonexchangeable sorbed fraction). Field cases are used to demonstrate the screening approach and to outline the primary considerations involved in accurately applying sequential extraction procedures to support the of MNA for site remediation. The results of these case studies provide strong evidence that site-specific screening and the use of sequential extraction procedures are effective methods for evaluating natural attenuation for metals impacted sites.     

The Health Risk Assessment Approach,a Tool for Managing Risks on the Scale of a Territory: A French Experience

In France, regulatory analysis of the environment and human health potential consequences is implemented for an isolated industrial activity that requests an authorization to operate using the health risk assessment method. To date, the question is enlarged to the impact of the combination of multiple sources of pollution on the same territory. The main conclusions of the work launched by the French High Council of Public Health focus on four key points: (i) the utility of conducting such an analysis at a territory scale, (ii) the delimitation of the area, (iii) the conditions for the different stakeholders’ involvement, and (iv) the methodological specificities of the “zone health risk assessment.” The work encompassed literature reviews, seminars, and interviews of stakeholders. The utility of a Z-HRA is the central objective for the management of risk. It can no longer be conducted only for itself. The delimitation of the zone entails economic, political, environmental, and population aspects. Stakeholders become key actors in a steering and monitoring committee. Among methodological specificities, cumulative exposure comes first. Interpretation of the results should focus on risk management objectives. Finally, inclusion of Z-HRAs in flexible regulations that can be adapted to the local context is recommended.     

Shortcomings in USEPA's Approach for Predicting Risk Due to Consumption of Animal Food Products Impacted by Air Emissions from Hazardous Waste Combustion Facilities: A Case Study Involving Phthalates

As a part of the permitting process for hazardous waste combustion facilities, regulatory agencies are now conducting site-specific, multipathway risk assessments. In accordance with the approach established by the USEPA, the Texas Natural Resource Conservation Commission uses a prospective risk assessment paradigm whereby site-specific activity pattern and land use information is used to determine plausible exposure scenarios and pathways. A set of exposure scenarios defined as receptors (i.e., resident adult, resident child, farmer adult, farmer child, fisher adult and fisher child) is then assumed to be exposed via multiple applicable exposure pathways. In conducting such risk assessments, modeled air emissions of di-n-octyl phthalate (DNOP), at concentrations near or below detectable levels, have been observed to produce an unacceptable hazard in the farmer exposure scenario. Sensitivity analyses indicated that two key parameters affected hazard estimates for DNOP in the farmer scenario: the octanol-water partition coefficient (K_ow), which is used to predict bioaccumulation in animal tissue, and the metabolism factor, which is used to account for metabolism and elimination. Evidence indicates that K_ow values for highly lipophillie compounds are accurately determined using a slow-stir method. In addition, evidence indicates that the phthalates of interest are extensively metabolized and eliminated. However, current USEPA guidance includes geometric mean K_ow values for highly lipophillie compounds derived in part on methods that are outdated and no longer considered accurate. In addition, USEPA guidance only considers metabolism for bis-% ethylhexyl phthalate (BEHP). Collectively, these two shortcomings in the USEPA approach result in a 38-fold underestimation of hazard for BEHP and a 172,000-fold overestimation of hazard for DNOP.