An intensification of interest in environmental assessment during the last 2 decades has driven corporate efforts to better document environmental goals, improve environmental management systems, and increase awareness of the environmental and ecological effects of business operations. This trend has been motivated partly by regulatory requirements (such as the Toxics Release Inventory in the United States) and partly by the inclination of some large manufacturing firms to embrace a broader social and environmental mission characterized as “sustainability” or “ecoefficiency.” Moreover, the importance of measurable objectives in the US government has been recognized at least since the Government Performance Results Act of 1993, which was intended to both improve the efficiency of government and the confidence of the American public in government managers. However, in management of environmental crises—such as catastrophic oil or chemical spills—development of measurable performance standards has lagged. Consequently, government spill managers are unable to define success in terms that are easily communicated to public and other stakeholder groups, and they could be disadvantaged in their efforts to deploy response resources with maximum efficiency. In this paper, we present a typological review of environmental assessment measures and summarize some of the current practices and strategic goals among federal agencies with regard to oil and chemical spills. A general approach to organizing metrics for oil spill response, restoration, and recovery is also presented. The results could improve planning efforts and communication among different federal, state, and local agencies and public or stakeholder groups involved in spill management.

In order to get insight into the variation in calculated human exposure, the outputs of 7 European exposure models have been compared. Twenty scenarios, differing with respect to land use, soil type, and contaminant, formed the basis for calculating human exposure to soil contaminants. All calculations were performed twice: Once with a standardized set of parameters for all models and once with the own default parameters. This led to the conclusion that the variation in calculated total exposure (combining all exposure pathways) is large (the majority of the outputs is in between a factor of 100 higher and a factor of 100 lower than the scenario medians). In addition, variation for exposure due to indoor air inhalation is also large. The variation for exposure due to crop consumption is substantial (the majority of the outputs is in between a factor of 10 higher and a factor of 10 lower than the scenario medians) and limited for exposure due to soil ingestion (limited = the majority of the outputs is within a factor of 5 higher and a factor of 5 lower than the scenario medians). The variation in calculated exposure increases when a contaminant is more mobile and, particularly, more volatile. The variation due to selection of input parameters does only yield an additional variation over the variation due to model algorithms for exposure due to soil ingestion and, to a lesser extent, for exposure due to crop consumption. The variation in calculated exposure is not dependent on the soil type and hardly dependent (only for exposure due to soil ingestion) on land use. The choice of model is a very significant factor for the absolute value of calculated exposure. For the promotion of uniformity it was recommended to construct a toolbox for the calculation of human exposure, for general use, including standardized tools and flexible tools, the latter to account for region-specific or country-specific (geographical, ethnological, and cultural) elements and national policy decisions.

Handling uncertainty in the current European Union (EU) risk assessment of new and existing substances is problematic for several reasons. The known or quantifiable sources of uncertainty are mainly considered. Uncertainty is insufficiently, explicitly communicated to risk managers and decision makers but hidden and concealed in risk quotient numbers that appear to be certain and, therefore, create a false sense of certainty and protectiveness. The new EU chemical policy legislation, REACH, is an opportunity to learn from interdisciplinary thinking in order to evolve to smart risk assessment: an assessment in which awareness and openness to uncertainty is used to produce better characterizations and evaluations of risks. In a smart risk assessment context, quantifying uncertainty is not an aim but just a productive means to refine the assessment or to find alternative solutions for the problem at stake. Guidance and examples are given on how to differentiate, assess, and use uncertainty.

In order to test the value of an integrated approach for the analysis of health risks at contaminated sites, an integrated health risk assessment in a mining area was performed following 3 steps: 1) Environmental monitoring of surface soil, 2) assessment of exposure to metals in children and native rodents, and 3) DNA damage evaluation (comet assay) in children and rodents. These aspects also were studied in less exposed populations. Our results in humans showed that children living in the most polluted area (Villa de la Paz, Mexico) had higher lead blood concentrations (geometric mean of 13.8 μg/dL) and urinary arsenic levels (geometric mean of 52.1 μg/g creatinine) compared to children living in a control area (Matehuala, Mexico; blood lead of 7.3 μg/dL; urinary arsenic of 16.8 μg/g creatinine). Furthermore, the exposed children also had increased DNA damage (tail moment mean in Villa de la Paz of 4.8 vs 3.9 in Matehuala; p < 0.05). Results in rodents were identical. Animals captured in the polluted area had higher levels of arsenic (geometric mean of 1.3 μg/g in liver and 1.8 μg/g in kidney), lead (0.2 μg/g in liver and 0.9 μg/g in kidney), and cadmium (0.8 μg/g in liver and 2.2 μg/g in kidney), and increased DNA damage (tail moment mean of 18.2) when compared to control animals (arsenic in liver of 0.08 μg/g and kidney of 0.1 μg/g; lead in liver of 0.06 μg/g and kidney of 0.3 μg/g; cadmium in liver of 0.06 μg/g and kidney of 0.6 μg/g; and tail moment of 14.2). With the data in children and rodents, the weight-of-evidence for health risks (in this case DNA damage) associated with metal exposure in Villa de la Paz was strengthened. Therefore, a remediation program was easier to justify, and a feasibility study at this site is under way.

The immediate and delayed effects of embryonic exposure to low levels of polynuclear aromatic hydrocarbons (PAHs) have been shown to reduce survival to maturity by 50% in exposed pink salmon populations. This suggests that chronically exposed populations could be extirpated over relatively few generations, but the effect of density dependence on extirpation rate is unknown. This study examines the interaction of PAH effects and randomly varying density dependence on a simulated population. The simulation derives from 70 years of observations made on a single pink salmon population and toxicity studies involving a hatchery population in the same watershed. Results from simulations involving exposure of 100% of the population to effects consistent with an aqueous PAH concentration of 18 nL/L indicate an 80% decrease in population productivity and an 11% probability of extinction after 35 generations. In contrast, population growth rate declined by only 5%. Further decreases in survival relative to that of observed PAH effects rapidly increase the probability of extinction. Data from these simulations demonstrate that, at low levels of exposure, density dependence can compensate for reduced population size and buffer the population against extinction. However, if equilibrium size is depressed sufficiently, random environmental variation overcomes the buffering effect of density dependence and extinction probability increases. These data demonstrate that extinction probability and population size are more sensitive measures of population effects than growth rate for wild populations regulated by density dependence.

Results of published pesticide mixture toxicity experiments conducted with aquatic organisms were compiled and evaluated to assess the accuracy of predictive mixture models. Three types of models were evaluated: Concentration addition (CA), independent action (IA), and simple interaction (SI). The CA model was the most often tested (207 experiments), followed by SI (59) and IA (37). The reviewed experiments are listed in the Supplemental material to provide a resource for future investigators. The predictive accuracy of each model was quantified for each experiment by the model deviation ratio (MDR), which was calculated by dividing the predicted toxicity by the observed toxicity. Eighty-eight percent of all experiments that evaluated the CA model had observed effective concentrations within a factor of 2 of predicted values (MDR values from 0.5–2.0). The median MDR was 1, about 5% of MDRs were less than 0.5, and about 5% were greater than 2, indicating unbiased estimates overall. The predictive accuracy of CA and IA models was influenced, however, by the different modes of action (MOA) of the pesticides. For experiments with pesticides with the same MOA, CA more accurately predicted effective concentrations for more experiments compared to IA, which tended to underpredict toxicity. The IA model was somewhat more accurate than the CA model for most mixtures with different MOAs, but in most cases there were relatively small differences between the models. Additionally, 80% of SI experiments had an MDR value below 2.0 despite a bias towards experiments that are likely to have an interaction. Thus, results indicate that the CA model may be used as a slightly conservative, but broadly applicable model with a relatively small likelihood of underestimating effects due to interactions.

West Nile virus (WNV) has been a concern for people across the United States since the disease was initially observed in the summer of 1999. Since 1999, WNV has caused the largest arboviral encephalitis epidemic in US history. Vector control management programs have been intensively implemented to control mosquitoes that carry WNV. Our deterministic ecological risk assessment focused on 6 common mosquito adulticides used in vector control, including 3 pyrethroids (d-phenothrin, resmethrin, and permethrin), pyrethrins, and 2 organophosphates (malathion and naled). Piperonyl butoxide, a synergist for the pyrethroids, was also assessed. Both aquatic and terrestrial nontarget organisms were considered for acute and chronic exposures to the adulticides. Tier I exposure estimates were derived from ISCST3 and AERMOD for deposition and air concentrations affecting terrestrial organisms and PRZM-EXAMS for standard pond concentrations affecting aquatic organisms. Nontargets exposed to adulticides included small mammals, birds, as well as aquatic vertebrates and invertebrates in a pond subject to receiving the chemical via drift and runoff. Risk quotients were obtained by comparing exposures to toxic endpoints. All risk quotients were low indicating that risks to ecological receptors most likely were small.

The discharge of urban stormwater may cause a sudden temperature increase in receiving waters that may be harmful to fish and other aquatic organisms. A screening procedure is proposed with temperature thresholds for the runoff from roofs and roads as well as for the receiving water system to protect brown trout from thermal damage. The stormwater temperature is calculated on the basis of a simple thermodynamic estimate for different latitudes. Only receiving waters with maximum daily mean temperatures of 22 °C (T1) are considered potential habitats for brown trout. The maximum temperature for a 1-h exposure time with a safety margin for 100% survival is 25 °C (T2), the sudden temperature change at the beginning of a rain event must not exceed 7 °C (T3), and fish-egg development requires the daily maximum temperature in winter to be below 12 °C (T4). Examples of stormwater runoff from roof or road surfaces from Switzerland validate our approach within ±0.5 °C. Effects of runoff into receiving waters without detailed data can be predicted within ±0.8 °C. With the restriction by T1, T2 seems not to be an acute problem at Swiss latitudes. T3 could play a role, especially if a large amount of runoff is discharged in small and rather cool rivers and streams. Finally, T4 deserves more attention than hitherto given. The proposed procedure may be a useful tool for assessing the influence of urban stormwater on the temperature of the receiving waters, particularly with regard to predicting the thermal impacts of urban or suburban runoff to populations of brown trout.

A number of studies carried out in recent years have shown the presence of a wide range of contaminants in the Venice Lagoon. It is important to have a good understanding of the ecological quality of Venice Lagoon sediments in order to 1) define and locate areas where a threat to the environment is present and therefore an intervention is needed (i.e., in situ assessment and management); and 2) define sustainable and environmentally correct ways of managing sediments that are to be dredged for navigational purposes or in relation to other interventions (i.e., ex situ management). This study reports on a critical comparison of chemical quality of sediments in Venice Lagoon and its subregions. Data on the Venice Lagoon were compiled from several studies conducted during the past decade on surface sediment contamination; temporal variation and risks for contaminants at depth were not addressed. The comparison of observed pollutant concentrations with local and internationally used sediment quality guidelines (SQGs) was used as a tool to benchmark different sites and for a tier I (screening) ecological risk assessment. Meaning and relevance of a number of SQGs are discussed, together with the options available for carrying out the comparison with sediment data. The screening of the Venice Lagoon sediment quality is discussed from a risk-assessment perspective and appropriate values for use in an in situ–ex situ management framework are suggested. Although there were some differences depending upon which specific SQGs were applied, different SQGs provided the same general picture of screening risk in Venice Lagoon: Although there are geographic differences, median levels for several contaminants in surface sediments exceeded a number of SQGs. Many contaminants exceed threshold effects SQGs, and Hg exceeds probable effects SQGs in most sub-basins except the southern Lagoon. Venice Lagoon south has the lowest screening risk levels, Venice Lagoon central/north has the highest (and is nearest to the Porto Marghera and Venice City Canals sites). Ranges are high in all areas, therefore any remedial or disposal decision should use site-specific data.

The objective of this study was to carry out a critical comparison of data on the screening quality of surface sediments in Venice Lagoon (VL; main lagoon and its subbasins, Porto Marghera [PM], and Venice City Canals) and in other transitional and coastal ecosystems with various levels of human impact (urbanization and industrialization). To put VL in terms of reference and industrialized sites in the region, case studies were selected from the North Adriatic Region; to gain insight into how VL sediments compared to transitional areas throughout the world, case studies also were selected from a number of regions internationally. In order to compare regional levels of contamination, statistically processed sediment contaminant levels within a region (minimum, maximum, mean, and median), not individual sample values, are compared. The screening quality (relative to a variety of sediment quality guidelines) and the drivers of screening risk (based upon contaminant mixtures) of the VL sediments and other coastal and transitional sites are compared and discussed. The VL sediments have hazard quotients on the low end of the range typical of moderately urbanized and industrialized sites and higher than background conditions among the case studies reviewed. The Hg levels in the VL were generally higher than at other sites, and other contaminants were either equivalent or lower. Although sediments have somewhat higher levels of some contaminants and lower levels of other contaminants in PM and Venice City (VC) canals, levels for most contaminants are comparable to case studies with high levels of anthropogenic impact. For many contaminants of interest, PM (and for some, VC) sediments have some of the highest levels of any case study reviewed. How PM and VC rank when compared to other highly industrialized sites depends upon how data are synthesized and how ranges are taken into account. Actual risk must be evaluated using a weight-of-evidence approach, because natural background levels and site-specific bioavailability will differ both regionally and internationally.

In the July 2006 issue of Integrated Environmental Assessment and Management, a paper by Harwell and Gentile was published assessing the present ecological significance of the impacts from the Exxon Valdez oil spill (EVOS). First, this paper compares the major conclusions of Harwell and Gentile and a paper reviewing the current impacts of EVOS by Peterson et al. as published by Science in 2003. Stark differences exist between the conclusions of the 2 papers regarding continuing impacts. Part of the difference appears to be the infusion of different social values or policy goals into each. Normative science is the use or interpretation of data in support of specific values or policies. Examples of values or policies intertwined with science are constructs such as ecosystem health, ecosystem integrity, ecological significance, and recovery. Examination of the environmental risk assessment and toxicology literature reveals that the symptoms of normative science are common and the implications widespread. Separation of science from policy or at a minimum a transparent acknowledgment of the science–policy interaction is clearly necessary in order to obtain a clear picture of the ecological system under investigation.

The purpose of this paper is to discuss the effective use of quantitative modeling in environmental decision making, with a particular focus on problems of contaminated sediment and surface water. The intended audience includes both model developers and model users. Our goal is to facilitate more effective communication among model developers and those using the information produced by models to aid decision making. We provide a series of observations or conclusions we have reached in our experience that are as follows. A model is a tool for evaluating alternate hypotheses; a model itself is not a hypothesis. All decisions are actually based upon models, either explicitly or implicitly. Models are used to address diagnostic and prognostic questions. Models can provide value added when applied throughout the lifetime of a project. Uncertainty, and therefore the need for models, is greater in systems near background. Models can provide useful information even when based on relatively small data sets. The utility of a model depends on the strength of the constraints placed upon it. The calibration process can be only partially specified a priori. Model calibration and evaluation require multiple lines of evidence. Uncertainty analysis is both qualitative and quantitative. Validation is provided by the application of the model under a wide range of conditions. Communication of the strength of model constraints is critical to model acceptance. We conclude that while models are often used in the evaluation of contaminated sediment problems, distrust in the use of models remains strong. The assessment of uncertainty is the factor most limiting acceptability.

Because ecological services often are tied to specific species, the risk to populations is a critical endpoint and important feature of ecological risk assessments. In Part 1 of this series it was demonstrated that population scale assessment endpoints are important expressions of the valued components of ecological structures. This commentary reviews several of the characteristics of populations that can be evaluated and used in population scale risk assessments. Two attributes are evaluated as promising. The 1st attribute is the change in potential productivity of the population over a specified time period. The 2nd attribute is the change in the age structure of a population, expressed graphically or as a normalized effects vector (NEV). The NEV is a description of the change in age structure due to a toxicant or other stressor and appears to be characteristic of specific stressor effects.