Cremation,Air Pollution,and Special Use Permitting: A Case Study

Risks to health posed by emissions of hazardous air pollutants from crematories are emerging concerns. The presence of silver–mercury amalgams in bodies results in airborne emissions of mercury; and the combustion of essentially any material results in emissions of polychlorinated dibenzodioxins and furans (PCDD/Fs; “dioxins”). These and other trace emissions from crematories are not regulated at the U.S. federal or (typically) state level, but neighborhood concerns may necessitate quantitative evaluations of potential local impacts, and local officials may need to rely on such evaluations in order to determine whether and under what conditions to grant (or deny) operating permits. Here we present a case study in which these and other issues were evaluated. Using air dispersion models and health risk assessment models, we predicted exposures that would be within health-based guidelines. Concerned citizens provided information that seemed to suggest otherwise. In the end, communication, education, and compromise led to a favorable result.     

Monitoring PCDD/Fs in Soil and Herbage Samples Collected Near a Hazardous Waste Incinerator: Health Risks for the Population Living Nearby

In 1998, we started a wide environmental surveillance program focused on evaluating the environmental impact of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) emitted by a new hazardous waste incinerator (HWI) (Tarragona County, Catalonia, Spain) and assessing the potential health risks for the population living nearby. The HWI began regular operations in 1999. Since then, periodical surveys have been performed. We report here the results concerning PCDD/F levels in 40 soil and 40 herbage samples collected in years 2004 and 2005, respectively, in the vicinity of the HWI. The human health risks derived from exposure to PCDD/Fs were also assessed. PCDD/F concentrations in soils ranged from 0.06 to 12.60 ng I-TEQ/kg, with median and mean values of 0.65 and 1.14 ng I-TEQ/kg, respectively. In herbage, PCDD/F concentrations ranged from 0.03 to 1.57 ng I-TEQ/kg, with median and mean values of 0.31 and 0.40 ng I-TEQ/kg, respectively. A comparison of these results with those from the baseline survey shows that, after six years of regular operation, the HWI did not significantly increase PCDD/F levels in soils and herbage in the surrounding environment. Moreover, PCDD/F emissions from the HWI do not mean additional significant risks for the health of the individuals living in the vicinity of the facility. The results of the current study together with those of recent investigations in municipal waste incinerators indicate that, when adequately controlled for PCDD/F emissions, modern waste incinerators should not portend any special concern for the populations living nearby.     

Public Health Perspectives on Dioxin Risks: Two Decades of Evaluations

The paper provides an overview of approaches to dioxin risk assessment employed by different agencies worldwide over the past 20 years. Our insights regarding understanding of the toxicity of dioxins have advanced tremendously in recent years; however, important data gaps still exist. More information on topics such as mechanism of interaction, effects at low levels of exposure, interspecies differences, and sensitive populations is needed. Some differences exist between USEPA's approach to dioxin assessment and that of other health organizations around the world. The authors conclude that USEPA's reassessment of dioxin and related compounds may place too much confidence in the ability to accurately predict cancer risks at low doses. Further, it is important to derive health-based guidance values for noncancer end points especially in accordance with emerging reports that reproductive and developmental end points are very sensitive to dioxins. A worldwide convergence on the health assessment value being around 1 to 4?pg/kg/day is noted.     

Distribution of Daily Breathing Rates For Use in California's Air Toxics Hot Spots Program Risk Assessments

Data were combined from a study measuring breathing rates at various activities and two activity pattern studies to generate breathing rate distributions for children and adults. The children and adult breathing rate distributions were combined using a Monte Carlo technique to generate a breathing rate distribution for a lifetime spanning ages 0 to 70. The children's breathing rate distribution has a mean, standard deviation, median and 95^th percentile of 452, 67.7, 441, and 581 L/kg-day, respectively. The adult breathing rate distribution has a mean, standard deviation, median and 95^th percentile of 232, 64.6, 209, and 381 L/kg-day, respectively. The simulated 70-year distribution has a mean, standard deviation, median and 95^th percentile of 271, 57.9, 253, and 393 L/kg-day, respectively. The adult breathing rate distribution is based on 24-hour recall activity data that would not necessarily capture average activity patterns and therefore breathing rates. We utilized the human energy expenditure literature to validate the breathing rate distribution. We conclude that the breathing rate distribution is reasonable for chronic long-term risk assessment in California's Air Toxics Hot Spots program.     

Risk Assessment of Some PCDDs,PCDFs, Dioxin-Like PCBs,and PCBs in Contaminated Dairy Products: An Egyptian Pilot Case Study

Samples of butter, cream, and white cheese were collected from the city of Ismailia, Egypt, and analyzed for polychloro dibenzo-p-dioxins, pentachloro dibenzo-p-furans, and dioxin-like polychlorinated biphenyl, PCBs. Butter samples had the highest mean content of PCDD/F and dioxin-like PCBs. Butter samples were the most contaminated samples in all dairy products analyzed in this study, whereas white cheese samples were the least contaminated. The spectrum of congeners detected in butter and cream were similar, with all congeners at detectable levels, whereas the spectrum of congeners detected in white cheese differed, with some congeners, namely 1,2,3,4,7,8-Hexa CDD, 1,2,3,4,6,7,8-Hepta CDD, and 1,2,3,7,8,9-Hexa CDD below WHO TE toxicity levels. 1,2,3,7,7-PeCDD, with its high concentration, was the principal contributor to the TEQ intake in both cream and butter samples. Similarly, the high concentration of 2,3,4,7,8-PeCDF in cream, butter, and white cheese samples was the main factor contributing to their TEQ intake. Estimated intakes of PCDDs/Fs were 129.2, 115.8, and 51.25 pg WHO-TEQ/day for butter, cream, and white cheese, respectively. Taking into account the sum of PCDDs/Fs and dioxin-like PCBs, estimated intakes were, 171.7, 155.8, and 68 pg WHO-TEQ/day, for butter, cream, and white cheese, respectively. Assuming an average bodyweight of 60 kg (WHO-TEQ/kg), these levels correspond to bodyweight-normalized intake levels of .15, 2.92 and 0.95 pg WHO-TEQ/kg/day.     

Axes of Extrapolation in Risk Assessment

Extrapolation in risk assessment involves the use of data and information to estimate or predict something that has not been measured or observed. Reasons for extrapolation include that the number of combinations of environmental stressors and possible receptors is too large to characterize risks comprehensively, that direct characterization is sometimes impossible, and that the power to characterize risk in a particular situation can be enhanced by using information obtained in other similar situations. Three types of extrapolation are common in risk assessments: biological (including between taxa and across levels of biological organization), temporal, and spatial. They can be thought of conceptually as the axes of a 3-dimensional graph defining the state space of biological, temporal, and spatial scales within which extrapolations are made. Each of these types of extrapolation can introduce uncertainties into risk assessments. Such uncertainties may be reduced through synergistic research facilitated by the sharing of methods, models, and data used by human health and ecological scientists     

A Weight-of-Evidence Framework for Assessing Sediment (Or Other) Contamination: Improving Certainty in the Decision-Making Process

A basic framework is presented for the ecological weight-of-evidence (WOE) process for sediment assessment that clearly defines its essential elements and will improve the certainty of conclusions about whether or not impairment exists due to sediment contamination, and, if so, which stressors and biological species (or ecological responses) are of greatest concern. The essential “Certainty Elements” are addressed in a transparent best professional judgment (BPJ) process with multiple lines-of-evidence (LOE) ultimately quantitatively integrated (but not necessarily combined into a single value). The WOE Certainty Elements include: (1) Development of a conceptual model (showing linkages of critical receptors and ecosystem quality characteristics); (2) Explanation of linkages between measurement endpoint responses (direct and indirect with associated spatial/temporal dynamics) and conceptual model components; (3) Identification of possible natural and anthropogenic stressors with associated exposure dynamics; (4) Evaluation of appropriate and quantitatively based reference (background) comparison methods; (5) Consideration of advantages and limitations of quantification methods used to integrate LOE; (6) Consideration of advantages and limitations of each LOE used; (7) Evaluation of causality criteria used for each LOE during output verification and how they were implemented; and (8) Combining the LOE into a WOE matrix for interpretation, showing causality linkages in the conceptual model. The framework identifies several statistical approaches for integrating within LOE, the suitability of which depends on physical characteristics of the system and the scale/nature of impairment. The quantification approaches include: (1) Gradient (regression methods); (2) Paired reference/test (before/after control impact and ANOVA methods); (3) Multiple reference (ANOVA and multivariate methods); and 4) Gradient with reference (regression, ANOVA and multivariate methods). This WOE framework can be used for any environmental assessment and is most effective when incorporated into the initial and final study design stages (e.g., the Problem Formulation and Risk Characterization stages of a risk assessment) with reassessment throughout the project and decision-making process, rather than in a retrospective data analysis approach where key certainty elements cannot be adequately addressed.     

Joint PCB-Methylmercury Exposures and Neurobehavioral Outcomes

The level of intake at which methylmercury might result in neurobehavioral or neuro psychological deficits in children has been extensively debated in recent years. The human data base for methylmercury toxicity is very robust, particularly when compared with other environmental substances for which health guidance values have been developed by Federal organizations. However, despite the depth of the data base for methylmercury, some of the key studies have been clouded by the concurrent exposure of the study population to polychlorinated biphenys (PCBs) and other persistent organic pollutants (POPs). In this paper, the authors examine the key points comprising the methylmercury-PCB issue and contrast these with recent reports of concurrent methylmercury/PCB human exposures and laboratory studies. The authors conclude that research published to date concerning the Seychelles and Faroes Island populations suggests that both methylmercury and PCBs are jointly responsible for the effects reported in the Faroes. Further neurobehavioral testing in populations exposed to PCBs alone, as well as with methylmercury alone, is necessary to fully resolve the ongoing debate.     

Harmonizing the Incorporation of Uncertainty and Variability Into Risk Assessment: An International Approach

International harmonization of risk assessment approaches affords a number of opportunities and advantages. Overall, harmonization will lead to more efficient use of resources, but also will lead to better understanding amongst scientists and regulators worldwide. It is with these goals in mind that in 1994 the International Programme on Chemical Safety (IPCS) initiated its Project on the Harmonization of Approaches to the Assessment of Risk from Exposure to Chemicals (Harmonization Project). An ongoing activity under this project addresses uncertainty and variability in risk assessment. The goal of the overall activity is to promote harmonization of risk assessment methodologies for noncancer endpoints. However, given the common links in uncertainty and variability that apply across a range of end-point-specific activities, these links are identified wherever possible. This paper provides an overview of the IPCS Harmonization Project and reviews the activity and future plans related to uncertainty and variability.     

Use of Indicators in Ecological Risk Assessments for Persistent,Bioaccumulative Toxicants

This paper synthesizes several presentations on the use of indicators in ecological risk assessments for persistent, bioaccumulative toxicants (PBTs). The presentations were organized around two chemical case studies: (1) mercury, and (2) compounds that exhibit an Ah-receptor based mode-of-action. Presenters summarized the current practice of ecological risk assessment for these compounds and described research on known or suspected impacts. In addition, this paper addresses three special topics that apply broadly to all PBTs: (1) the convergence of ecological assessment and ecological risk assessment, (2) integration of ecological and human health risk assessment, and (3) risk assessments for population-level effects.     

Polychlorinated biphenyls in vegetable soils from Changchun,Northeast China: Concentrations,distribution, sources and human health risks

To investigate the occurrences of polychlorinated biphenyls (PCBs) in suburban vegetable soils of Changchun area, Northeast China, 106 urban vegetable soil samples were collected from Changchun City, Nongan County, Dehui City, Yushu City, Jiutai City, Shuangyang District. We analyzed the concentrations, compositions and sources of 7 PCBs in top soils of Changchun area, and evaluated the non-carcinogenic and carcinogenic risk of PCBs pollution to exposed population. The total concentrations of 7 PCBs ranged from 1.31 to 148 ng/g dry weight (dw) with a mean value of 42.0 ng/g and dominated by Hepta-CBs and Penta-CBs. Principal component analysis (PCA) revealed that PCB pollution in soils of Changchun area mainly related to transportation, vehicle emissions, paints and other industries. Human health risk assessment showed that the cumulative non-carcinogenic and the cumulative carcinogenic risk in children and adults in the industrial land and residential land were acceptable, considering only 7 PCBs homologues were analyzed in this study, the actual risk could be higher.     

Electronic waste—a modern form of risk? On the consequences of the delay between the increasing generation of electronic waste and regulations to manage this increase

This article addresses the relation between the current proliferation of Information and Communication Technology (ICT) goods and services and the development of different kinds of risk assessments and policy documents. The ambition is to shed light on a, hithertho, less-discussed aspect of the development of risk assessments and policy documents, namely the time span between the development of new technologies and the development of regulatory frameworks. The concept of risk and danger can be seen as a potential means through which we can start to think about the consequences of the delay between the increased generation of electronic waste (e-waste) and the regulations to manage this increase. By using e-waste as a case study, this article provides the basis for a more general understanding of the relation between the development of new technologies and the development of regulatory frameworks. While it might be difficult to pin down the effects that this delay had/has for the subsequent development of ICTs, this article highlights the importance of taking into account not only how and by whom risk assessments and policy documents are developed, but also when they are developed in relation to the technologies that they serve to regulate.     

Weight-of-Evidence Approaches for Assessing Ecosystem Impairment

It is challenging determining whether an ecosystem is impaired. The complexity of direct and indirect interactions between physical, biological and chemical components with their varying temporal and spatial scales generally renders use of multiple assessment approaches mandatory, with a consequent need to integrate different lines-of-evidence. Integration generally involves some form of weight-ofevidence (WOE). WOE approaches reported in the literature vary broadly from subjective and qualitative to quantitative. No standard approach exists and no accepted guidelines exist describing how a WOE process should be conducted. This review summarizes the advantages, limitations, and uncertainties of different WOE approaches, critical issues involved in selecting and executing different lines-ofevidence, and the process for subsequent characterization of the likelihood of impairment.     

Uncertainty in the Extrapolation from Individual Effects to Impacts upon Landscapes

Uncertainty is inherent in extrapolating from effects upon the individual to alterations in ecological structure or function. Subtle differences in individuals within a population can give rise to significant evolutionary events. Populations are part of ecological structures, systems that are clearly complex, requiring an understanding of the interacting components, stochastic inputs and spatial scales. A series of patch-dynamic models is used to illustrate the importance of spatial arrangement and initial population size in predicting effects at a landscape level. The importance of understanding the spatial structure of a population in uncertainty reduction is addressed.     

Evaluation of Three Measures of Exposure Concentration: A Case Study of Surface Sediment Concentrations in the Passaic River

Arithmetic and lognormal means historically have been used as estimates of exposure concentration for both human health and ecological risk assessment. Past risk assessment guidance has emphasized the need to include all available informa tion, particularly regarding the spatial and temporal aspects of data and exposure. One estimate of exposure concentration that includes spatial information is the 95% upper confidence limit (UCL) of the area weighted mean. An area weighted mean is calculated using weightings based on the ratio of the area associated with a sample location and the total area of the study area. Currently, U.S. Environmental Protection Agency (USEPA) risk assessment guidance recommends the use of the 95% UCL of the arithmetic mean as the most appropriate measure of exposure concentration for soil and sediment in human health and ecological risk assess ments. The purpose of this study was two fold: (1) to evaluate the use of the 95% UCL of the area weighted mean vs. the 95% UCL of the arithmetic mean for the lognormal distribution and the normal distribution using a large data set from a recent riverine sediment characterization study, and (2) to evaluate the potential associated with the different approaches for reduction in surface sediment exposure concentrations for 2,3,7,8 TCDD and coplanar polychlorinated biphenyls (PCBs) for several subsets of the data. The results of this evaluation indicated that there was no significant reduction in exposure concentrations of the study area surface sediments after any of the selected higher concentration data points had been removed from the various data subsets. In addition, this evaluation indicated that, due to its dependence on the variance of the data, the 95% UCL of the arithmetic mean for a lognormal distribution produced subset exposure concentrations that were higher than the calculated concentrations of the full data set and produced the smallest percent changes in concentration compared to the other two measures. Based on this analysis, the 95% UCL of the area weighted mean was determined to be the most stable and appropriate estimator of exposure concentration for surface sediments.