Empirical Scaling of Single Oral Lethal Doses Across Mammalian Species Based on a Large Database

The scaling of administered doses to achieve equal degrees of toxic effect in different species has been relatively poorly examined for noncancer toxicity, either empirically or theoretically. We investigate empirical patterns in the correspondence of single oral dose LD, values across several mammalian species for a large number of chemicals based on data reported in the RTECSQ database maintained by the National Institute for Occupational Safety and Health. We find a good correspondence of LD, values across species when the dose levels are expressed in terms of mgadministered per kg of body mass. Our findings contrast with earlier analyses that support scaling doses by the 3/4-power of body mass to achieve equal subacute toxicity of antineoplastic agents. We suggest that, especially for severe toxicity, single- and repeated-dosing regimes may have different cross-species scaling properties, as they may depend on standing levels of defenses and rate of regeneration of defenses, respectively.     

Assessment of Health Risk from Exposure to Contaminated Soil

The risk to human health posed by contaminated soil in a residential area depends on the potential extent of exposure to soil and on the toxic properties of the contaminants. A detailed soil exposure analysis is presented for young children, older children, and adults living in a house surrounded by contaminated soil. From this analysis, a lifetime exposure model is derived and used to assess chronic health risks.     

The Role of Geographic Scale in Monitoring Environmental Justice

Utilizing the concept of environmental justice, this paper examines the differential burdens of toxic and hazardous waste facilities locations in low income minority communities. The association between the presence of facilities and socioeconomic characteristics of places are examined for the state of South Carolina at three different spatial scales: counties, census tracts, and census block groups. Three different types of hazardous waste/toxic facilities are also examined: Toxic Release Inventory (TRI) sites, Treatment, Storage, and Disposal sites (TSD), and inactive hazardous waste sites. At the county level, there was some association between the presence of toxic/hazardous waste facilities and race and income. In South Carolina, this translates to a disproportionate burden on White, more affluent communities in metropolitan areas, rather than low income minority communities. At both the census tract and block group levels, there is no association between race and the location of toxic/hazardous waste facilities. There are slight differences in the income levels between tracts and block groups with facilities and those without. This localized ecology of hazard sources must be expanded to include emission/discharge data in order to adequately address environmental justice issues on who bears the burdens of environmental contamination.     

Understanding the Followers of Toxic Leaders: Toxic Illusio and Personal Uncertainty

Toxic leaders are one of the main threats to the wellbeing of people in the workplace and in society in general, and followers play a critical role in constructing and maintaining toxic leaders. In this narrative review, we draw on Bourdieu's concept of illusio and incorporate it with the social and cognitive psychology approaches in an attempt to frame the dynamic system that sustains toxic leadership through continued support of the followers. More specifically, as we introduce the illusio perspective in a process‐relational context to the toxic leadership discussion, we (i) address the allure of toxic leaders as an incentive for followers to join the toxic illusio as a way to cope with their high personal uncertainty and (ii) illustrate the mechanisms and processes that motivate followers of toxic leaders to remain in the toxic illusio once they join. In this context, we also briefly discuss and differentiate between the ethical and moral dimensions of toxic leadership.     

Probabilistic Integrated Human Mixture Risk Assessment of Multiple Metals Through Seafood Consumption

Inorganic arsenic (iAs), cadmium (Cd), lead (Pb), and methylmercury (MeHg) are toxic metals that cause substantial health concern and are present in various seafood items. This study linked probabilistic risk assessment to the interactive hazard index (HI_INT) approach to assess the human mixture risk posed by the dietary intake of iAs, Cd, Pb, and MeHg from seafood for different age populations, and joint toxic actions and toxic interactions among metals were also considered in the assessment. We found that, in combination, an iAs–Cd–Pb–MeHg mixture synergistically causes neurological toxicity. Furthermore, an iAs–Cd–Pb mixture antagonistically causes renal and hematological effects and additively causes cardiovascular effect. Our results demonstrated that if toxic interactions are not considered, the health risk may be overestimated or underestimated. The 50th percentile HI_INT estimates in all age populations for neurological, renal, cardiovascular, and hematological effects were lower than 1; however, the 97.5th percentile HI_INT estimates might exceed 1. In particular, toddlers and preschoolers had the highest neurological risk, with 0.16 and 0.19 probabilities, respectively, of neurological HI_INT exceeding 1. Saltwater fish consumption was the principal contributor to the health risk. We suggest that regular monitoring of metal levels in seafood, more precise dietary surveys, further toxicological data, and risk–benefit analysis of seafood consumption are warranted to improve the accuracy of human mixture risk assessment and determine optimal consumption.     

Perceptions of and reactions to leader toxicity: Do leader–follower relationships and identification with victim matter?

This experimental study examined the influence of leader–follower relationships (i.e., LMX) and target salience on perceptions of leader toxicity and intentions to challenge the leader. There are no studies that evaluate the effect of leader–follower relationships on these two variables. Participants (n = 298) with work experience viewed a video of a leader acting in a destructive manner toward a target. As predicted, LMX out-group participants perceived the leader to be toxic to a greater extent than participants with favored status, and indicated greater intent to challenge the leader. With regard to target salience, the results also showed that observers perceived the leader to be toxic to a greater extent when the leader was targeting someone in their LMX grouping, but there were no significant differences in challenging intentions based on the target's LMX status. Implications for leaders, followers, and organizations are discussed.     

Risk/Benefit Assessments of Human Diseases: Optimum Dose for Intervention

A simple procedure is proposed in order to quantify the tradeoff between a loss suffered from an illness due to exposure to a microbial pathogen and a loss due to a toxic effect, perhaps a different illness, induced by a disinfectant employed to reduce the microbial exposure. Estimates of these two types of risk as a function of disinfectant dose and their associated relative losses provide information for the estimation of the optimum dose of disinfectant that minimizes the total expected loss. The estimates of the optimum dose and expected relative total loss were similar regardless of whether the beta-Poisson, log-logistic, or extreme value function was used to model the risk of illness due to exposure to a microbial pathogen. This is because the optimum dose of the disinfectant and resultant expected minimum loss depend upon the estimated slope (first derivative) of the models at low levels of risk, which appear to be similar for these three models at low levels of risk. Similarly, the choice among these three models does not appear critical for estimating the slope at low levels of risk for the toxic effect induced by the use of a disinfectant. For the proposed procedure to estimate the optimum disinfectant dose, it is not necessary to have absolute values for the losses due to microbial-induced or disinfectant-induced illness, but only relative losses are required. All aspects of the problem are amenable to sensitivity analyses. The issue of risk/benefit tradeoffs, more appropriately called risk/risk tradeoffs, does not appear to be an insurmountable problem.     

Managing toxic wastes—After Bhopal and Sandoz

Recent events at Bhopal and Sandoz have raised a new concern over chemical accidents and the handling of toxic wastes. In a comparative framework, this paper analyses American and European experiences in the legislative arena and in dealing with substantial chemical accidents. The costs and actions of both firms and governments in response to, and clean-up of, these accidents are noted. Finally, specific actions for governments and multinational firms are addressed to lessen both the toxic waste and toxic accident problem.     

Rachel Carson's Toxic Discourse: Conjectures on Counterpublics,Stakeholders and the “Occupy Movement”

This article draws attention to the origins, forms, and implications of “toxic discourse” as a genre central to the understanding of the public sphere in business in society. Rachel Carson's Silent Spring is used as a pivotal cultural document establishing “toxic discourse” as an ongoing form of moral narrative rooted in the rationality of counterpublics. Toxic discourse is framed within a center/periphery model in which toxic discourse gains salience in periods of economic dislocation and uncertainty. In these periods, toxic discourse draws together those on the periphery or counterpublics who otherwise would not unite in their opposition to the center. The article critically examines how stakeholder theory, despite making sense of the public sphere for agents of organizations, glosses counterpublics and relegates toxic discourse, as evident in the “Occupy Movement,” to the ephemeral role of temporary, disruptive protest groups with very little of substance to communicate.     

Mercury,Polychlorinated Biphenyls,Selenium, and Fatty Acids in Tribal Fish Harvests of the Upper Great Lakes

The Chippewa Ottawa Resource Authority monitors fish contaminants in Anishinaabe (Great Lake Native American) tribal fisheries. This article updates previously reported trends in two persistent bioaccumulative toxic (PBT) substances that are the primary contributors to consumption advisory limits for these fish: methylmercury (MeHg) and polychlorinated biphenyls (PCBs). Also, we report, for the first time, an analysis of nutritional benefit bioindicators and metrics in these same Upper Great Lakes fish harvests: selenium (Se) and omega‐3 fatty acids (PUFA‐3s). A novel risk/benefit quantification originally presented by Ginsberg et al. is reported here to characterize the tradeoffs between fatty acid benefits and toxic MeHg health outcomes. We also report a Se benefit metric to characterize the possible protective value against MeHg neurotoxicity based on Ralston et al. Congruent with Anishinaabe cultural motivations to consume fish from their ancestral fisheries, nutritional content was high in locally caught fish and, in some respects, superior to farmed/store‐bought fish. These Great Lakes fish still contained levels of PBTs that require careful education and guidance for consumers. However, the contaminant trends suggest that these fish need not be abandoned as important (both culturally and nutritionally) food sources for the Anishinaabe who harvested them.     

A Risk Assessment for Selected Lead-Induced Health Effects: An Example of a General Methodology

The research described here is part of a larger risk assessment project to aid the U.S. Environmental Protection Agency (EPA) in its review of the primary National Ambient Air Quality Standard for lead. The methodology can be applied to many situations in which a policy decision about a toxic substance is required in the face of incomplete data. Numerical results are presented for three potentially adverse lead-induced effects of interest to EPA: elevated erythrocyte protoporphyrin (EP), hemoglobin (Hb) decrement, and intelligence quotient (IQ) decrement.     

Sampling Strategies for Toxic Air Contaminants

Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants.     

Upper Confidence Limits on Excess Risk for Quantitative Responses

The definition and observation of clear-cut adverse health effects for continuous (quantitative) responses, such as altered body weights or organ weights, are difficult propositions. Thus, methods of risk assessment commonly used for binary (quantal) toxic responses such as cancer are not directly applicable. In this paper, two methods for calculating upper confidence limits on excess risk for quantitative toxic effects are proposed, based on a particular definition of an adverse quantitative response. The methods are illustrated with data from a dose-response study, and their performance is evaluated with a Monte Carlo simulation study.     

Exposure Assessment: Methods of Analysis for Environmental Carcinogens1

Human populations are exposed to environmental carcinogens in both indoor and outdoor atmospheres. Recent studies indicate that pollutant concentrations are generally higher in indoor atmospheres than in outdoor. Environmental pollutants that occur in indoor air from a variety of sources include radon, asbestos, organic and inorganic compounds, and certain particles (e.g., tobacco smoke). Some of the gases or vapors are adsorbed on suspended particulate matter, whereas others exist entirely in the gas phase or are distributed between the latter and a particle-bound state. Because of differences in chemical and physical properties, each class of carcinogens generally requires different sampling and analytical methods. In addition, a single indoor environment may contain a wide variety of air pollutants from different sources. Unfortunately, no single best approach currently exists for the quantitative determination of such complex mixtures and, for practical reasons, only the more toxic or the more abundant pollutants are usually measured. This paper summarizes the currently available monitoring methods for selected environmental pollutants found in indoor atmospheres. In addition, some possible sources for those pollutants are identified.     

Costs of Health Damage from Atmospheric Emissions of Toxic Metals: Part 1—Methods and Results

Significant quantities of toxic metals are emitted to the air by the incineration of waste, as well as by the combustion of coal and oil. To optimize the regulations for their emissions one needs to know the cost of their damage. That requires an impact pathway analysis, with realistic dispersion models, exposure‐response functions, and monetary values. In this article we explain the method and assumptions and present results for arsenic, cadmium, mercury, and lead, the most important toxic metals in terms of damage cost. We also estimate their contribution to the damage cost of waste incineration and electric power from coal for typical situations in Europe. The damage costs of As, Cd, and Pb are much higher than previous estimates because of a large number of new epidemiological studies, implying more and more serious health effects than what had been known before. New cost‐benefit studies for the abatement of toxic metal emissions are advisable. The discussion of the epidemiological studies and the derivation of exposure‐response functions are presented in two companion articles, one for As and Cd, the other for Hg and Pb.     

The Risk of Photochemical Reactions

In January 1987, an incident occurred at a petrochemical complex in Salavat, Russia. The incident resulted in the poisioning of 17 people by the products of photochemical smog. This paper describes the incident and discusses the possibility of chemical reactions that pose toxic hazardous situations for chemical plant personnel. Pollutants present in the atmosphere as a result of continuous releases can result in the formation of toxic substances and the poisioning of people, even when permissible levels of concentrations are not exceeded for the initial pollutants. In addition, this paper addresses the need to consider the possibility of secondary chemical reactions in the environment while planning chemical plant activity.     

Risk assessment of major hazards and its application in urban planning: a case study

With the rapid development of industry in China, the number of establishments that are proposed or under construction is increasing year by year, and many are industries that handle flammable, explosive, toxic, harmful, and dangerous substances. Accidents such as fire, explosion, and toxic diffusion inevitably happen. Accidents resulting from these major hazards in cities cause a large number of casualties and property losses. It is increasingly important to analyze the risk of major hazards in cities realistically and to suitably plan and utilize the surrounding land based on the risk analysis results, thereby reducing the hazards. A theoretical system for risk assessment of major hazards in cities is proposed in this article, and the major hazard risk for the entire city is analyzed quantitatively. Risks of various major accidents are considered together, superposition effect is analyzed, individual risk contours of the entire city are drawn out, and the level of risk in the city is assessed using "as low as reasonably practicable" guidelines. After the entire city's individual risk distribution is obtained, risk zones are divided according to corresponding individual risk value of HSE, and land-use planning suggestions are proposed. Finally, a city in China is used as an example to illustrate the risk assessment process of the city's major hazard and its application in urban land-use planning. The proposed method has a certain theoretical and practical significance in establishing and improving risk analysis of major hazard and urban land-use planning. On the one hand, major urban public risk is avoided; further, the land is utilized in the best possible way in order to obtain the maximum benefit from its use.     

A Spatial Approach to Environmental Risk Assessment of PAH Contamination

The extent of remediation of contaminated industrial sites depends on spatial heterogeneity of contaminant concentration and spatially explicit risk characterization. We used sequential Gaussian simulation (SGS) and indicator kriging (IK) to describe the spatial distribution of polycyclic aromatic hydrocarbons (PAHs), pH, electric conductivity, particle aggregate distribution, water holding capacity, and total organic carbon, and quantitative relations among them, in a creosote polluted soil in southern Sweden. The geostatistical analyses were combined with risk analyses, in which the total toxic equivalent concentration of the PAH mixture was calculated from the soil concentrations of individual PAHs and compared with ecotoxicological effect concentrations and regulatory threshold values in block sizes of 1.8 × 1.8 m. Most PAHs were spatially autocorrelated and appeared in several hot spots. The risk calculated by SGS was more confined to specific hot spot areas than the risk calculated by IK, and 40–50% of the site had PAH concentrations exceeding the threshold values with a probability of 80% and higher. The toxic equivalent concentration of the PAH mixture was dependent on the spatial distribution of organic carbon, showing the importance of assessing risk by a combination of measurements of PAH and organic carbon concentrations. Essentially, the same risk distribution pattern was maintained when Monte Carlo simulations were used for implementation of risk in larger (5 × 5 m), economically more feasible remediation blocks, but a smaller area became of great concern for remediation when the simulations included PAH partitioning to two separate sources, creosote and natural, of organic matter, rather than one general.     

A Simple Data Transformation for Estimating Benchmark Doses in Developmental Toxicity Experiments

Developmental anomalies induced by toxic chemicals may be identified using laboratory experiments with rats, mice or rabbits. Multinomial responses of fetuses from the same mother are often positively correlated, resulting in overdispersion relative to multinomial variation. In this article, a simple data transformation based on the concept of generalized design effects due to Rao-Scott is proposed for dose-response modeling of developmental toxicity. After scaling the original multinomial data using the average design effect, standard methods for analysis of uncorrected multinomial data can be applied. Benchmark doses derived using this approach are comparable to those obtained using generalized estimating equations with an extended Dirichlet-trinomial covariance function to describe the dispersion of the original data. This empirical agreement, coupled with a large sample theoretical justification of the Rao-Scott transformation, confirms the applicability of the statistical methods proposed in this article for developmental toxicity risk assessment.     

Risk Characterization of Methyl tertiary Butyl Ether (MTBE) in Tap Water

Methyl tertiary butyl ether (MTBE) can enter surface water and groundwater through wet atmospheric deposition or as a result of fuel leaks and spills. About 30% of the U.S. population lives in areas where MTBE is in regular use. Ninety-five percent of this population is unlikely to be exposed to MTBE in tap water at concentrations exceeding 2 ppb, and most will be exposed to concentrations that are much lower and may be zero. About 5% of this population may be exposed to higher levels of MTBE in tap water, resulting from fuel tank leaks and spills into surface or groundwater used for potable water supplies. This paper describes the concentration ranges found and anticipated in surface and groundwater, and estimates the distribution of doses experienced by humans using water containing MTBE to drink, prepare food, and shower/bathe. The toxic properties (including potency) of MTBE when ingested, inhaled, and in contact with the skin are summarized. Using a range of human toxic potency values derived from animal studies, margins of exposure (MOE) associated with alternative chronic exposure scenarios are estimated to range from 1700 to 140,000. Maximum concentrations of MTBE in tap water anticipated not to cause adverse health effects are determined to range from 700 to 14,000 ppb. The results of this analysis demonstrate that no health risks are likely to be associated with chronic and subchronic human exposures to MTBE in tap water. Although some individuals may be exposed to very high concentrations of MTBE in tap water immediately following a localized spill, these exposures are likely to be brief in duration due to large-scale dilution and rapid volatilization of MTBE, the institution of emergency response and remediation measures to minimize human exposures, and the low taste and odor thresholds of MTBE which ensure that its presence in tap water is readily detected at concentrations well below the threshold for human injury.