Dietary Uptake of Highly Hydrophobic Chemicals by Rainbow Trout (Oncorhynchus Mykiss).

Rainbow trout (Oncorhynchus mykiss) was exposed through the diet to a mixture of non-ionic organic chemicals for 28 d, followed by a depuration phase, in accordance with OECD method 305. The mixture included hexachlorobenzene (HCB), 2,2',5,5'-tetrachlorobiphenyl (PCB-52), 2,2',5,5'-hexachlorobiphenyl (PCB-153), decachlorobiphenyl (PCB-209), decabromodiphenyl ether (BDE209), decabromodiphenyl ethane (DBDPE), bis-(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH), perchloro-p-terphenyl (p-TCP), perchloro-m-terphenyl (m-TCP), and perchloro-p-quaterphenyl (p-QTCP), the latter six of which are considered highly hydrophobic based on n-octanol/water partition coefficients (K) greater than 10. All chemicals had first-order uptake and elimination kinetics except p-QTCP, whose kinetics could not be verified due to limitations of analytical detection in the elimination phase.

Review of DDT, DDE, DDD, DDMU and DDMS Toxicity Data for Organisms Used in Estuarine and Marine Sediment Toxicity Tests.

The open literature was searched for laboratory toxicity data for marine/estuarine organisms exposed to dichlorodiphenyltrichloroethane (DDT) and its degradation products of dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD), dichlorodiphenylchloroethylene (DDMU), and dichlorodiphenylchloroethane (DDMS). The goal of the review was to determine water-column toxicity values that could be used for porewater-based assessment of sediment toxicity. Data for individual compounds (and isomers thereof) in this group were very limited; most available data were for mixtures of multiple compounds, some defined and others undefined.

Review of per- and polyfluoroalkyl substances (PFAS) bioaccumulation in earthworms.

Per- and polyfluoroalkyl substances (PFAS) are widely used across the globe in commercial products such textiles, firefighting foams, and surface coatings. Some PFAS, such as perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are known to be bioaccumulative. Numerous terrestrial ecosystems including sites near PFAS manufacturing facilities, facilities using PFAS in their manufacturing processes, firefighting training areas, landfills, and agricultural fields treated with some pesticide formulations, have been contaminated with PFAS.

Biota-Sediment Accumulation Factors for Per- and Polyfluoroalkyl Substances.

Per- and polyfluoroalkyl substances (PFAS) are widely used in commercial products such textiles, firefighting foams, and surface coatings across the globe and some PFAS are known to be bioaccumulative in aquatic species. The ultimate sink for numerous anthropogenic chemicals is the sediments in lakes, rivers, and oceans. To understand the relationship between sediment and aquatic species, a literature search was performed and biota-sediment accumulation factors (BSAFs) data for 17 taxonomic classes were assembled.

Bioaccumulation of Bis-(2-ethylhexyl)-3,4,5,6-tetrabromophthalate and Mono-(2-ethylhexyl)-3,4,5,6-tetrabromophthalate by Lumbriculus variegatus.

The brominated flame retardant bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) is used widely in consumer items including polyurethane foam used in furniture. Information on its bioaccumulation in aquatic species is limited. In the current study, sediment bioaccumulation tests with the oligochaete Lumbriculus variegatus were performed on a spiked natural sediment equilibrated for 14.

Evaluation of Published Bioconcentration Factor (BCF) and Bioaccumulation Factor (BAF) Data for Per- and Polyfluoroalkyl Substances Across Aquatic Species.

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals of concern across the globe, and some of the PFAS chemicals are known to be bioaccumulative in aquatic species. A literature search for bioconcentration factors (BCFs) and bioaccumulation factors (BAFs) for PFAS has been done, and data for 22 taxonomic classes were assembled. The assembled data were evaluated for quality, and for gaps and limitations in bioaccumulation information for the PFAS universe of chemicals.

Estimating n-octanol-water partition coefficients for neutral highly hydrophobic chemicals using measured n-butanol-water partition coefficients.

Direct measurement of the n-octanol partition coefficients (K) for highly hydrophobic organic chemicals is extremely difficult because of the extremely low concentrations present in the water phase. n-Butanol/water partition coefficients (K) are generally much lower than K due to the increased solubility of solute in the alcohol saturated aqueous phase, and therefore become easier to measure. We measured the K for 25 neutral organic chemicals having measured log Ks ranging from 2 to 9 and 4 additional highly hydrophobic chemicals, with unmeasured Ks, having estimated log Ks ranging from 6 to 18.

Practical advice for selecting or determining trophic magnification factors for application under the European Union Water Framework Directive.

European Union Directive 2013/39/EU, which amended and updated the Water Framework Directive (WFD; 2000/60/EC) and its daughter directive (2008/105/EC), sets Environmental Quality Standards for biota (EQS ) for a number of bioaccumulative chemicals. These chemicals pose a threat to both aquatic wildlife and human health via the consumption of contaminated prey or the intake of contaminated food originating from the aquatic environment. EU member states will need to establish programs to monitor the concentration of 11 priority substances in biota and assess compliance against these new standards for the classification of surface water bodies.

Bioaccumulation of Highly Hydrophobic Chemicals by Lumbriculus variegatus.

Bioaccumulation of highly hydrophobic chemicals (log K> 8) from contaminated sediments by Lumbriculus variegatus has been studied for relatively few chemicals, and the measured and model predicted biota-sediment accumulation factors (BSAFs) can differ by orders of magnitude. In the current study, sediment bioaccumulation tests with L. variegatus were performed on sediments dosed with chemicals having a wide range of predicted n-octanol/water partition coefficients (K; 10-10), including some higher than most highly hydrophobic chemicals studied to date.

Sediment Bioaccumulation Test with Lumbriculus variegatus: Effects of Organism Loading.

At contaminated sediment sites, the bioavailability of contaminants in sediments is assessed using sediment-bioaccumulation tests with Lumbriculus variegates (Lv). The testing protocols recommend that ratio of total organic carbon (TOC) in sediment to L. variegatus (dry weight) (TOC/Lv) should be no less than 50:1.

Review of existing terrestrial bioaccumulation models and terrestrial bioaccumulation modeling needs for organic chemicals.

Protocols for terrestrial bioaccumulation assessments are far less-developed than for aquatic systems. This article reviews modeling approaches that can be used to assess the terrestrial bioaccumulation potential of commercial organic chemicals. Models exist for plant, invertebrate, mammal, and avian species and for entire terrestrial food webs, including some that consider spatial factors.

Sediment bioaccumulation test with Lumbriculus variegatus: effects of feeding.

Standard sediment-bioaccumulation test methods specify that Lumbriculus variegatus should not be fed during the 28-day exposure. This lack of feeding can lead to decreases in L. variegatus weight and lipid content during the 28-day exposure period.

Evaluation of micro-colorimetric lipid determination method with samples prepared using sonication and accelerated solvent extraction methods.

Two common laboratory extraction techniques were evaluated for routine use with the micro-colorimetric lipid determination method developed by Van Handel (1985) [2] and recently validated for small samples by Inouye and Lotufo (2006) [1]. With the accelerated solvent extraction method using chloroform:methanol solvent and the colorimetric lipid determination method, 28 of 30 samples had significant proportional bias (α=1%, determined using standard additions) and 1 of 30 samples had significant constant bias (α=1%, determined using Youden Blank measurements). With sonic extraction, 0 of 6 samples had significant proportional bias (α=1%) and 1 of 6 samples had significant constant bias (α=1%).

Evaluation of PCB bioaccumulation by Lumbriculus variegatus in field-collected sediments.

Review of data from several contaminated sediment sites suggested that biota-sediment accumulation factors (BSAFs) declined with increasing contaminant concentrations in the sediment. To evaluate the consistency and possible causes of this behavior, polychlorinated biphenyl (PCB)-contaminated sediment samples from the Hudson, Grasse, and Fox River Superfund sites were used in sediment bioaccumulation tests with the freshwater oligochaete, Lumbriculus variegatus, with PCB concentrations in interstitial water (IW) quantified using polyoxymethylene passive samplers. Measured BSAFs tended to decrease with increasing PCB concentration in sediment, especially for the more highly chlorinated congeners.

Comparing laboratory and field measured bioaccumulation endpoints.

An approach for comparing laboratory and field measures of bioaccumulation is presented to facilitate the interpretation of different sources of bioaccumulation data. Differences in numerical scales and units are eliminated by converting the data to dimensionless fugacity (or concentration-normalized) ratios. The approach expresses bioaccumulation metrics in terms of the equilibrium status of the chemical, with respect to a reference phase.

Comparing laboratory- and field-measured biota-sediment accumulation factors.

Standardized laboratory protocols for measuring the accumulation of chemicals from sediments are used in assessing new and existing chemicals, evaluating navigational dredging materials, and establishing site-specific biota-sediment accumulation factors (BSAFs) for contaminated sediment sites. The BSAFs resulting from the testing protocols provide insight into the behavior and risks associated with individual chemicals. In addition to laboratory measurement, BSAFs can also be calculated from field data, including samples from studies using in situ exposure chambers and caging studies.

Bioaccumulation data from laboratory and field studies: are they comparable?

Once they are released into the environment, a number of chemicals are known to bioaccumulate in organisms, sometimes to concentrations that may threaten the individual or their predators. However, use of physical or chemical properties or results from laboratory bioaccumulation tests to predict concentrations sometimes found in wild organisms remains a challenge. How well laboratory studies and field measurements agree or disagree, and the cause of any discrepancies, is a subject of great interest and discussion from both a scientific and a regulatory perspective.

Direct application of biota-sediment accumulation factors.

In the early stages of risk assessments for sites with contaminated sediments, predictions of risks are often complicated or limited by sparse or inadequate bioaccumulation data. These limitations often require risk assessors to estimate bioaccumulation relationships in order to complete the assessments of risk. In the present study, the errors are evaluated with the simple (direct) application of field measured biota-sediment accumulation factors (BSAFs) to other species at a specific location, and to the same species and/or other species at other locations within a site and to other sites.

Revisiting bioaccumulation criteria for POPs and PBT assessments.

Scientists from academia, industry, and government reviewed current international regulations for the screening of commercial chemicals for bioaccumulation in the context of the current state of bioaccumulation science. On the basis of this review, several recommendations were proposed, including a scientific definition for "bioaccumulative substances," improved criteria for the characterization of bioaccumulative substances (including the trophic magnification factor and the biomagnification factor), novel methods for measuring and calculating bioaccumulation properties, and a framework for screening commercial chemicals for bioaccumulative substances. The proposed framework for bioaccumulation screening improves current practices by reducing miscategorization, making more effective use of available bioaccumulation data that currently cannot be considered, reducing the need for animal testing, providing simpler and cheaper test protocols for animal studies in case animal studies are necessary, making use of alternative testing strategies, including in vitro and in silico metabolic transformation assays, and providing a scientific foundation for bioaccumulation screening that can act to harmonize bioaccumulation screening among various jurisdictions.

Guidance for evaluating in vivo fish bioaccumulation data.

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.

Toxicity equivalency values for polychlorinated biphenyl mixtures.

For aquatic, avian, and mammalian species, dioxin equivalency values (TEQs) were computed for Aroclor, Clophen, Kanechlor, Chlorofen, Sovol, Delor, Phenoclor, and Chinese polychlorinated biphenyl (PCB) mixtures by using World Health Organization toxicity equivalency factors (TEFs) and compound-specific compositional data for PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) for the individual mixtures. The TEQs were similar across the different PCB product lines for mixtures of similar chlorine content. Depending on the PCB mixture, the polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in the mixture contributed anywhere from 0 to 96% of the total TEQs, and the impact of PCDD/Fs was greatest for the fish TEQs.

In vitro-in vivo extrapolation of quantitative hepatic biotransformation data for fish. II. Modeled effects on chemical bioaccumulation.

Hypothetical in vitro biotransformation rate and affinity values for fish were extrapolated to a set of in vivo whole-body metabolism rate constants. A one-compartment model was then used to investigate potential effects of metabolism on chemical bioaccumulation as a function of octanol/water partitioning (Kow). In a second model-based effort, in vitro data were incorporated into a physiologically based toxicokinetic (PBTK) model for fish.

Workgroup report: review of fish bioaccumulation databases used to identify persistent, bioaccumulative, toxic substances.

Chemical management programs strive to protect human health and the environment by accurately identifying persistent, bioaccumulative, toxic substances and restricting their use in commerce. The advance of these programs is challenged by the reality that few empirical data are available for the tens of thousands of commercial substances that require evaluation. Therefore, most preliminary assessments rely on model predictions and data extrapolation.