Currently, the laboratory-derived fish bioconcentration factor (BCF) serves as one of the primary data sources used to assess the potential for a chemical to bioaccumulate. Consequently, fish BCF values serve a central role in decision making and provide the basis for development of quantitative structure–property relationships (QSPRs) used to predict the bioaccumulation potential of untested compounds. However, practical guidance for critically reviewing experimental BCF studies is limited. This lack of transparent guidance hinders improvement in predictive models and can lead to uninformed chemical management decisions. To address this concern, a multiple-stakeholder workshop of experts from government, industry, and academia was convened by the International Life Sciences Institute Health and Environmental Sciences Institute to examine the data availability and quality issues associated with in vivo fish bioconcentration and bioaccumulation data. This paper provides guidance for evaluating key aspects of study design and conduct that must be considered when judging the reliability and adequacy of reported laboratory bioaccumulation data. Key criteria identified for judging study reliability include 1) clear specification of test substance and fish species investigated, 2) analysis of test substance in both fish tissue and exposure medium, 3) no significant adverse effects on exposed test fish, and 4) a reported test BCF that reflects steady-state conditions with unambiguous units. This guidance is then applied to 2 data-rich chemicals (anthracene and 2,3,7,8-tetrachlorodibenzo-p-dioxin) to illustrate the critical need for applying a systematic data quality assessment process. Use of these guidelines will foster development of more accurate QSPR models, improve the performance and reporting of future laboratory studies, and strengthen the technical basis for bioaccumulation assessment in chemicals management.

In 2000, a set of sediment effect concentrations (SECs) was published for evaluating the toxicity of polychlorinated biphenyls (PCBs) in freshwater, estuarine, and marine sediments. According to the developers, these consensus-based SECs reconcile existing sediment quality guidelines (SQGs) that have been developed using various approaches, reflect causal rather than correlative effects, and can be used to determine the spatial extent of injury to sediment-dwelling organisms. In the present study, a critical evaluation of the SECs was conducted based on the original documents and databases used to develop the underlying SQGs for the SECs, as well as the original documents and data sets used to determine the predictive ability of the SECs. Results of the critical evaluation indicated that the SECs are simple mathematical constructs that share the same limitations as their underlying SQGs. The SECs are questionable “consensus” values, because many of their underlying SQGs are dissimilar, misclassified, or redundant with other SQGs. Because nearly all of the data sets included in the databases used to calculate the underlying SQGs, or to validate the SECs, were affected by elevated concentrations of multiple co-occurring chemicals, it was not possible to conclusively identify PCBs as the cause of any of the observed sediment toxicity. The SECs, and most of their underlying SQGs, are likely biased by the fact that their underlying databases are composed primarily of PCB concentrations less than 0.5 mg/kg dry weight. Comparisons between the SECs and bioaccumulation-based SQGs calculated using the equilibrium partitioning approach provide no information on whether the SECs are causally related to sediment toxicity. The primary available median lethal concentration (LC50) value for PCBs, determined using spiked-sediment toxicity tests, has limited applicability to most contaminated aquatic environments, because it was determined using an unusually low total organic carbon content. Finally, site-specific application of the SECs indicated that their predictive ability was very low, that concentration–response relationships were not found for a variety of test species and toxicity endpoints at PCB concentrations greater than the SECs, and that some of the highest survival and growth values in the toxicity tests were found at PCB concentrations considerably greater than the SECs. Based on the results of this study, we conclude that the SECs for PCBs should be used only in the screening-level evaluations that typically precede more direct assessments of sediment toxicity at individual study sites, and should not be used to predict the presence of sediment toxicity. Contrary to the conclusions of the SEC developers, the SECs do not reconcile existing SQGs, do not reflect causal effects, and should not be used to determine the spatial extent of injury to sediment-dwelling organisms.

EDITOR'S NOTE: This is 1 of 5 papers reporting on the results of a 4-year project to develop an environmental risk-based decision support tool, to assist the oil industry in establishing cost-effective measures for reducing risk to the marine environment from drilling discharges.

This paper briefly summarizes the ERMS project and presents the developed model by showing results from environmental fates and risk calculations of a discharge from offshore drilling operations. The developed model calculates environmental risks for the water column and sediments resulting from exposure to toxic stressors (e.g., chemicals) and nontoxic stressors (e.g., suspended particles, sediment burial). The approach is based on existing risk assessment techniques described in the European Union technical guidance document on risk assessment and species sensitivity distributions. The model calculates an environmental impact factor, which characterizes the overall potential impact on the marine environment in terms of potentially impacted water volume and sediment area. The ERMS project started in 2003 and was finalized in 2007. In total, 28 scientific reports and 9 scientific papers have been delivered from the ERMS project ( http://www.sintef.no/erms).

EDITOR'S NOTE: This is 1 of 5 papers reporting on the results of a 4-year project to develop an environmental risk-based decision support tool, to assist the oil industry in establishing cost-effective measures for reducing risk to the marine environment from drilling discharges.

In order to improve the ecological status of aquatic systems, both toxic (e.g., chemical) and nontoxic stressors (e.g., suspended particles) should be evaluated. This paper describes an approach to environmental risk assessment of drilling discharges to the sea. These discharges might lead to concentrations of toxic compounds and suspended clay particles in the water compartment and concentrations of toxic compounds, burial of biota, change in sediment structure, and oxygen depletion in marine sediments. The main challenges were to apply existing protocols for environmental risk assessment to nontoxic stressors and to combine risks arising from exposure to these stressors with risk from chemical exposure. The defined approach is based on species sensitivity distributions (SSDs). In addition, precautionary principles from the EU-Technical Guidance Document were incorporated to assure that the method is acceptable in a regulatory context. For all stressors a protocol was defined to construct an SSD for no observed effect concentrations (or levels; NOEC(L)-SSD) to allow for the calculation of the potentially affected fraction of species from predicted exposures. Depending on the availability of data, a NOEC-SSD for toxicants can either be directly based on available NOECs or constructed from the predicted no effect concentration and the variation in sensitivity among species. For nontoxic stressors a NOEL-SSD can be extrapolated from an SSD based on effect or field data. Potentially affected fractions of species at predicted exposures are combined into an overall risk estimate. The developed approach facilitates environmental management of drilling discharges and can be applied to define risk-mitigating measures for both toxic and nontoxic stress.

EDITOR'S NOTE: This is 1 of 5 papers reporting on the results of a 4-year project to develop an environmental risk-based decision support tool, to assist the oil industry in establishing cost-effective measures for reducing risk to the marine environment from drilling discharges.

Drilling mud and associated drill cuttings are the largest volume wastes associated with drilling of oil and gas wells and often are discharged to the ocean from offshore drilling platforms. Barite (BaSO₄) often is added as a weighting agent to drilling muds to counteract pressure in the geologic formations being drilled, preventing a blowout. Some commercial drilling mud barites contain elevated (compared to marine sediments) concentrations of several metals. The metals, if bioavailable, may harm the local marine ecosystem. The bioavailable fraction of metals is the fraction that dissolves from the nearly insoluble, solid barite into seawater or sediment porewater. Barite–seawater and barite–porewater distribution coefficients (Kd) were calculated for determining the predicted environmental concentration (PEC; the bioavailable fraction) of metals from drilling mud barite in the water column and sediments, respectively. Values for Kd_{barite–seawater} and Kd_{barite–porewater} were calculated for barium, cadmium, chromium, copper, mercury, lead, and zinc in different grades of barite. Log Kd_{barite–seawater} values were higher (solubility was lower) for metals in the produced water plume than log Kd_{barite–porewater} values for metals in sediments. The most soluble metals were cadmium and zinc and the least soluble were mercury and copper. Log K_d values can be used with data on concentrations of metals in barite and of barite in the drilling mud–cuttings plume and in bottom sediments to calculate PEC_seawater and PEC_sediment.

EDITOR'S NOTE: This is 1 of 5 papers reporting on the results of a 4-year project to develop an environmental risk-based decision support tool, to assist the oil industry in establishing cost-effective measures for reducing risk to the marine environment from drilling discharges.

Drilling discharges are complex mixtures of chemical components and particles which might lead to toxic and nontoxic stress in the environment. In order to be able to evaluate the potential environmental consequences of such discharges in the water column and in sediments, a numerical model was developed. The model includes water column stratification, ocean currents and turbulence, natural burial, bioturbation, and biodegradation of organic matter in the sediment. Accounting for these processes, the fate of the discharge is modeled for the water column, including near-field mixing and plume motion, far-field mixing, and transport. The fate of the discharge is also modeled for the sediment, including sea floor deposition, and mixing due to bioturbation. Formulas are provided for the calculation of suspended matter and chemical concentrations in the water column, and burial, change in grain size, oxygen depletion, and chemical concentrations in the sediment. The model is fully 3-dimensional and time dependent. It uses a Lagrangian approach for the water column based on moving particles that represent the properties of the release and an Eulerian approach for the sediment based on calculation of the properties of matter in a grid. The model will be used to calculate the environmental risk, both in the water column and in sediments, from drilling discharges. It can serve as a tool to define risk mitigating measures, and as such it provides guidance towards the “zero harm” goal.

EDITOR'S NOTE: This is 1 of 5 papers reporting on the results of a 4-year project to develop an environmental risk-based decision support tool, to assist the oil industry in establishing cost-effective measures for reducing risk to the marine environment from drilling discharges.

In order to achieve the offshore petroleum industries “zero harm” goal to the environment, the environmental impact factor for drilling discharges was developed as a tool to identify and quantify the environmental risks associated with disposal of drilling discharges to the marine environment. As an initial step in this work the main categories of substances associated with drilling discharges and assumed to contribute to toxic or nontoxic stress were identified and evaluated for inclusion in the risk assessment. The selection were based on the known toxicological properties of the substances, or the total amount discharged together with their potential for accumulation in the water column or sediments to levels that could be expected to cause toxic or nontoxic stress to the biota. Based on these criteria 3 categories of chemicals were identified for risk assessment the water column and sediments: Natural organic substances, metals, and drilling fluid chemicals. Several approaches for deriving the environmentally safe threshold concentrations as predicted no effect concentrations were evaluated in the process. For the water column consensus were reached for using the species sensitivity distribution approach for metals and the assessment factor approach for natural organic substances and added drilling chemicals. For the sediments the equilibrium partitioning approach was selected for all three categories of chemicals. The theoretically derived sediment quality criteria were compared to field-derived threshold effect values based on statistical approaches applied on sediment monitoring data from the Norwegian Continental Shelf. The basis for derivation of predicted no effect concentration values for drilling discharges should be consistent with the principles of environmental risk assessment as described in the Technical Guidance Document on Risk Assessment issued by the European Union.

The purpose of this paper is to present a new risk-based approach developed by Environment Canada for ranking pesticides and their potential risk to aquatic life. These rankings are compared to those generated using a more traditional score-based approach. Two hundred and twelve active ingredients registered in Canada for use in agricultural field crops were included in this assessment. For each major aquatic taxon assessed (fish, insects, crustaceans, algae, and macrophytes), risk was calculated by dividing the 96-h estimated environmental concentration (modeled using parameters such as the application rate and method as well as physicochemical properties) by HC5 values (obtained through calculations of species sensitivity distribution–based toxicity endpoints). The traditional approach assigned scores based on toxicity endpoints in standard test species as well as physicochemical properties associated with the potential for aquatic contamination. A number of similarities were observed between the rankings but also notable differences. Only 22 active ingredients were common to the top 50 ranking positions from both approaches. The main reasons that accounted for the discrepancies between both rankings were the choice of toxicity endpoints, whether based on single or multiple species; the taxonomic breadth of retained data; the use of scores versus risk quotients; and the choices made in situations where multiple data points were available. We conclude that a risk-based approach that considers a broad representation of species toxicity data and estimates of runoff and drift concentration in receiving aquatic systems (even from generic application scenarios) is a more realistic representation of potential toxicological effects and a superior method of ranking products for the risk they pose to the aquatic environment.

Watersheds have historically been used as the appropriate spatial classification unit for managing water resources. However, geology, soil type, predominant vegetation, and climate have obvious influences on water quality and are not constrained by watercourses or political boundaries. This concept has evolved for several decades and developed the concept of ecoregions and other spatial schemes. While this approach to water resource management has considered the interaction between water quality and biological integrity (aquatic community structure and assemblage), it has not been applied in the context of predicting aquatic toxicity. As such, a previously published study providing a chemical and toxicological data set consisting of 24 sampling sites in South Carolina, USA, and was used to develop empirical models for predicting acute copper (Cu) toxicity to larval fathead minnows (Pimephales promelas). Moreover, numerous spatial classifications (hydrologic units, ecoregions, stream order, adjacent land use, and proximity to certain land uses) and seasonality were used to delineate sites and develop empirical models based on these different classifications. An independent sampling and testing regime was implemented to determine the performance of the empirical models and whether certain classifications could be used to extrapolate toxicity data across spatial landscapes. Additionally, a computational model (biotic ligand model [BLM]) for deriving site-specific water quality criteria for Cu also was used as a reference for current regulatory application. Empirical models based on delineations of stream order, hydrologic unit, and downstream distance to urbanization accurately predicted at least 60% of the observed Cu toxicity values within the supplemental data set. Delineations based on adjacent land use, ecoregions, and seasons were not as useful for predicting acute Cu toxicity but demonstrated better performance than the BLM.

When waterfowl (Anatidae) ingest sediment as they feed, they are exposed to the environmental contaminants in those sediments. The rate of ingestion may be key to assessing environmental risk. Rates of sediment ingestion were estimated as from <2% to 22% in 16 species of waterfowl collected in the northeastern United States. The piscivorous red-breasted merganser (Mergus serrator) ingested sediment at the lowest rate and the benthos-feeding canvasback (Aythya valisineria) at the highest rate. Sediment ingestion rates were related to diet and to the sediments where waterfowl fed. Waterfowl ingested the least sediment from hard-bottomed habitats with fast-moving water and ingested the most sediment from soft-bottomed areas with slow-moving water. Understanding the greater hazards from contaminants associated with low-flow habitats may help in prioritizing sites to be remediated. The tundra swan (Cygnus columbianus), which ingests sediment at an estimated 8.4% of its diet, dry weight, is suggested as a potential generic model for use in environmental risk assessments designed to protect waterfowl.

The basis for all US Environmental Protection Agency (USEPA) acute ambient water quality criteria is the chemical specific final acute value (FAV; an estimate of the concentration of the chemical corresponding to a cumulative probability of 0.05 of acute toxicity values for all genera with which acceptable acute tests have been conducted). The acute criterion for all chemicals is equal to the chemical's FAV divided by an application factor of 2. The intention of dividing the FAV by a factor of 2 is to convert the acute toxicity value to an incipient acute toxicity value, resulting in an acute criterion concentration that will protect against toxic effects to aquatic organisms. In the case of copper (Cu) in saltwater, the FAV is reduced from the normal 0.05 probability to equal to the genus mean acute value (GMAV; the geometric mean of copper effect concentration 50% [EC50] values) of the economically important marine bivalves of the genus Mytilus. Analyses to determine an application factor specific to Mytilus and copper were performed to assess the adequacy of the application factor of 2. An estimate of a dissolved copper application factor that is specific to and protective of Mytilus was determined using the results of sixty-four 48-h embryo survival and shell development copper toxicity tests of natural water samples collected from sites around the United States. A variety of point-estimate effects concentrations (EC1, EC5, EC10, EC20, and chronic values [ChV]) and statistical toxic-effect endpoints (no observed effect concentration [NOEC] and lowest observed effect concentration [LOEC]) were derived from the test results and compared. The most similar toxic effect endpoint estimates were EC1 ≈ NOEC, EC10 ≈ ChV, and EC20 ≈ LOEC. Probabilistic methods were used to determine a specific application factor with a high probability of providing protection. This analysis suggests that an application factor of 1.5 (rather than 2) is adequate to provide a high degree of protection against acute effects of dissolved copper to Mytilus. In context, this translates to an acute saltwater dissolved copper criterion of 6.4 μg Cu/L compared to the current acute criterion of 4.8 μg Cu/L.

Environment Canada's Disposal at Sea Programme hosted the Contaminated Dredged Material Management Decisions Workshop in Montreal, Quebec, Canada, on 28–30 November 2006. The workshop brought together over 50 sediment assessment and management experts from academic, industrial, and regulatory backgrounds and charged them with drafting a potential framework to assess contaminated dredged materials and compare the risks of various disposal alternatives. This article summarizes the recommendations made during the workshop concerning the development of sediment assessment tools, the interpretation of these tools, and the essential attributes of a comparative risk assessment process. The major outcomes of the workshop include a strong recommendation to develop a national dredging or sediment management strategy, a potential decision-making framework for the assessment of dredged materials and comparative risk assessment of disposal options, and the expansion of minimum sediment characterization requirements for nonroutine disposal permit applications.