Sediment toxicity assessment: comparison of standard and new testing designs

Comparison of microplastic isolation and extraction procedures from marine sediments

Microplastics (MPs) are small (<5 mm) plastic particles which pose a threat to marine ecosystems. Identifying MPs is crucial for understanding their fate and effects. Many MP extraction methods exist, but procedural differences prevent meaningful comparisons across datasets. This method comparison examines the efficiency of five methods for extracting MPs (40-710 μm) from marine sediments. Known quantities of MPs were spiked into sediments. The MPs were extracted and enumerated to demonstrate percent recovery. Findings determined that sediment matrix, MP properties, and extraction method affect the percent recovery of MPs from sediments. Average recoveries of spiked microplastics were between 0 and 87.4% and varied greatly by sediment type, microplastic, and method of extraction. In general, larger particle and lower density MPs were more effectively recovered. Marine sediments low in organic matter and with larger grain size also had higher percent recoveries of MPs. These findings support the need for method optimization and unified procedures.

Magnitude of acute toxicity of marine sediments amended with conventional copper and nanocopper

It is well known that copper (Cu) is toxic to marine organisms. We measured and compared the acute toxicity of several forms of Cu (including nanoCu) amended into a marine sediment with mysids and amphipods. For all the forms of Cu tested, toxicity, measured as the median lethal concentration, ranged from 708 to > 2400 mg Cu/kg (dry sediment) for mysids and 258 to 1070 mg Cu/kg (dry sediment) for amphipods. Environ Toxicol Chem 2018;37:2677-2681. © 2018 SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Effects of micronized and nano-copper azole on marine benthic communities

The widespread use of copper nanomaterials (CuNMs) as antibacterial and antifouling agents in consumer products increases the risk for metal contamination and adverse effects in aquatic environments. Information gaps exist on the potential toxicity of CuNMs in marine environments. We exposed field-collected marine meio- and macrobenthic communities to sediments spiked with micronized copper azole (MCA) using a novel method that brings intact benthic cores into the laboratory and exposes the organisms via surface application of sediments. Treatments included field and laboratory controls, 3 spiked sediments: low-MCA (51.9 mg/kg sediment), high-MCA (519 mg/kg sediment), and CuSO₄ (519 mg/kg sediment). In addition, single-species acute testing was performed with both MCA and CuSO_4. Our results indicate that meio- and macrofaunal assemblages exposed to High-MCA and CuSO₄ treatments differed significantly from both the laboratory control and the low-MCA treatments. Differences in macrofauna were driven by decreases in 3 Podocopa ostracod species, the bivalve Gemma gemma, and the polychaetes Exogone verugera and Prionospio heterobranchia relative to the laboratory control. Differences in the meiofaunal community are largely driven by nematodes. The benthic community test results were more sensitive than the single-species test results. Findings of this investigation indicate that CuNMs represent a source of risk to marine benthic communities comparable to that of dissolved Cu. Environ Toxicol Chem 2018;37:362-375. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Aggregation, Sedimentation, Dissolution, and Bioavailability of Quantum Dots in Estuarine Systems

To understand their fate and transport in estuarine systems, the aggregation, sedimentation, and dissolution of CdSe quantum dots (QDs) in seawater were investigated. Hydrodynamic size increased from 40 to 60 nm to >1 mm within 1 h in seawater, and the aggregates were highly polydispersed. Their sedimentation rates in seawater were measured to be 4-10 mm/day. Humic acid (HA), further increased their size and polydispersity, and slowed sedimentation. Light increased their dissolution and release of dissolved Cd. The ZnS shell also slowed release of Cd ions. With sufficient light, HA increased the dissolution of QDs, while with low light, HA alone did not change their dissolution. The benthic zone in estuarine systems is the most probable long-term destination of QDs due to aggregation and sedimentation. The bioavailability of was evaluated using the mysid Americamysis bahia. The 7-day LC50s of particulate and dissolved QDs were 290 and 23 μg (total Cd)/L, respectively. For mysids, the acute toxicity appears to be from Cd ions; however, research on the effects of QDs should be conducted with other organisms where QDs may be lodged in critical tissues such as gills or filtering apparatus and Cd ions may be released and delivered directly to those tissues.

Diagnosis of potential stressors adversely affecting benthic invertebrate communities in Greenwich Bay, Rhode Island, USA

Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was impaired. Second, the presence of source, stressor, and effect were established. Then linkages between source, stressor, and effect were developed. This allows identification of probable stressors adversely affecting the waterbody. Three pollutant categories were assessed: chemicals, nutrients, and suspended sediments. This weight of evidence approach indicated that Greenwich Bay was primarily impacted by eutrophication-related stressors. The sediments of Greenwich Bay were carbon enriched and low dissolved oxygen concentrations were commonly seen, especially in the western portions of Greenwich Bay. The benthic community was depauperate, as would be expected under oxygen stress. Although our analysis indicated that contaminant loads in Greenwich Bay were at concentrations where adverse effects might be expected, no toxicity was observed, as a result of high levels of organic carbon in these sediments reducing contaminant bioavailability. Our analysis also indicated that suspended sediment impacts were likely nonexistent for much of the Bay. This analysis demonstrates that the diagnostic procedure was useful to organize and assess the potential stressors impacting the ecological well-being of Greenwich Bay. This diagnostic procedure is useful for management of waterbodies impacted by multiple stressors. Environ Toxicol Chem 2017;36:449-462. © 2016 SETAC.

Toxicity, bioaccumulation, and biotransformation of silver nanoparticles in marine organisms

The toxicity, bioaccumulation, and biotransformation of citrate and polyvinylpyrrolidone (PVP) coated silver nanoparticles (NPs) (AgNP-citrate and AgNP-PVP) in marine organisms via marine sediment exposure was investigated. Results from 7-d sediment toxicity tests indicate that AgNP-citrate and AgNP-PVP did not exhibit toxicity to the amphipod (Ampelisca abdita) and mysid (Americamysis bahia) at ≤75 mg/kg dry wt. A 28-d bioaccumulation study showed that Ag was significantly accumulated in the marine polychaete Nereis virens (N. virens) in the AgNP-citrate, AgNP-PVP and a conventional salt (AgNO3) treatments. Synchrotron X-ray absorption spectroscopy (XAS) results showed the distribution of Ag species in marine sediments amended with AgNP-citrate, AgNP-PVP, and AgNO3 was AgCl (50–65%) > Ag2S (32–42%) > Ag metal (Ag0) (3–11%). In N virens, AgCl (25–59%) and Ag2S (10–31%) generally decreased and, Ag metal (32–44%) increased, relative to the sediments. The patterns of speciation in the worm were different depending upon the coating of the AgNP and both types of AgNPs were different than the AgNO3 salt. These results show that the AgNP surface capping agents influenced Ag uptake, biotransformation, and/or excretion. To our knowledge, this is the first demonstration of the bioaccumulation and speciation of AgNPs in a marine organism (N. virens).

Bioaccumulation and toxicity of single-walled carbon nanotubes to benthic organisms at the base of the marine food chain

As the use of single-walled carbon nanotubes (SWNTs) increases over time, so does the potential for environmental release. This research aimed to determine the toxicity, bioavailability, and bioaccumulation of SWNTs in marine benthic organisms at the base of the food chain. The toxicity of SWNTs was tested in a whole sediment exposure with the amphipod Ampelisca abdita and the mysid Americamysis bahia. In addition, SWNTs were amended to sediment and/or food matrices to determine their bioavailability and bioaccumulation through these routes in A. abdita, A. bahia, and the estuarine amphipod Leptocheirus plumulosus. No significant mortality to any species via sediment or food matrices was observed at concentrations up to 100 ppm. A novel near-infrared fluorescence spectroscopic method was utilized to measure and characterize the body burdens of pristine SWNTs in nondepurated and depurated organisms. We did not detect SWNTs in depurated organisms but quantified them in nondepurated A. abdita fed SWNT-amended algae. After a 28-d exposure to [(14) C]SWNT-amended sediment (100 µg/g) and algae (100 µg/g), [(14) C]SWNT was detected in depurated and nondepurated L. plumulosus amphipods at 0.50 µg/g and 5.38 µg/g, respectively. The results indicate that SWNTs are bioaccessible to marine benthic organisms but do not appear to accumulate or cause toxicity.

Use of a novel sediment exposure to determine the effects of triclosan on estuarine benthic communities

Triclosan (5-chloro-2-[2,4-dichlorophenoxy]phenol) is a relatively new, commonly used antimicrobial compound found in many personal care products. Triclosan is toxic to marine organisms at the micrograms per liter level, can photodegrade to a dioxin, can accumulate in humans, and has been found to be stable in marine sediments for over 30 years. To determine the effects of triclosan on marine benthic communities, intact sediment cores were brought into the laboratory and held under flowing seawater conditions. A 2-cm layer of triclosan-spiked sediment was applied to the surface, and after a two-week exposure the meio- and macrofaunal communities were assessed for differences in composition relative to nonspiked cores. A high triclosan treatment (180 mg/kg dry wt) affected both the meio- and the macrobenthic communities. There were no discernible differences with a low-triclosan treatment (14 mg/kg dry wt). This exposure method is effective for testing the benthic community response to sediment contaminants, but improvements should be made with regard to the amount and method of applying the overlying sediment to prevent smothering of fragile benthic organisms.

Distribution, magnitude and characterization of the toxicity of Ukrainian estuarine sediments

During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine's estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation.

Assessment of supercritical fluid extraction use in whole sediment toxicity identification evaluations

Supercritical fluid extraction (SFE) with pure CO(2) was assessed as a confirmatory tool in phase III of whole sediment toxicity identification evaluations (TIEs). The SFE procedure was assessed on two reference sediments and three contaminated sediments by using a combination of toxicological and chemical measurements to quantify effectiveness. Sediment toxicity pre- and post-SFE treatment was quantified with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia), and nonionic organic contaminants (NOCs) polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in sediments, overlying waters, and interstitial waters. In general, use of SFE with the reference sediments was successful, with survival averaging 91% in post-SFE treatments. Substantial toxicity reductions and contaminant removal from sediments and water samples generated from extracted sediments of up to 99% in two of the contaminated sediments demonstrated SFE effectiveness. Furthermore, toxicological responses for these SFE-treated sediments showed comparable results to those from the same sediments treated with the powdered coconut charcoal addition manipulation. These data demonstrated the utility of SFE in phase III of a whole sediment TIE. Conversely, in one of the contaminated sediments, the SFE treatments had no effect on sediment toxicity, whereas sediment concentrations of PCBs and PAHs were reduced. We propose that, for some sediments, the SFE treatment may result in the release of otherwise nonbioavailable cationic metals that subsequently cause toxicity to test organisms. Overall, SFE treatment was found to be effective for reducing the toxicity and concentrations of NOCs in some contaminated sediments. However, these studies suggest that SFE treatment may enhance toxicity with some sediments, indicating that care must be taken when applying SFE and interpreting the results.

Limitations of reverse polyethylene samplers (RePES) for evaluating toxicity of field contaminated sediments

Passive samplers are used to measure dissolved nonionic organic contaminants (NOCs) in environmental media. More recently, reverse polyethylene samplers (RePES) have been used with spiked sediments to recreate interstitial water exposure concentrations and observed toxicity. In the present study, RePES were used with field contaminated sediments. The RePES was not capable of recreating the pattern of toxicity with the amphipod and mysid observed with intact field sediments. Decreased survival in the RePES exposures as compared to the whole sediment exposures was most likely caused by an overexposure to NOCs due to a lack of surrogate black carbon in the RePES system. As an alternative, aqueous phase studies were performed in which polyethylene was allowed to equilibrate with slurries of intact sediments for 3 weeks. Three weeks was found to be an insufficient amount of time for the polyethylene to equilibrate with the sediment. An additional study demonstrated 3 months was sufficient for lower contaminant concentrations, but might not be an adequate amount of time for more highly contaminated sediments. The aqueous phase transfer approach may be useful if equilibration is sufficiently long, although this length of time may be impractical for use in certain applications, such as toxicity identification evaluations (TIEs).

Bioavailability assessment of a contaminated field sediment from Patrick Bayou, Texas, USA: toxicity identification evaluation and equilibrium partitioning

Contaminated sediments are commonly found in urbanized harbors. At sufficiently high contaminant levels, sediments can cause toxicity to aquatic organisms and impair benthic communities. As a result, remediation is necessary and diagnosing the cause of sediment toxicity becomes imperative. In the present study, six sediments from a highly industrialized area in Patrick Bayou (TX, USA) were subjected to initial toxicity testing with the mysid, Americamysis bahia, and the amphipod, Ampelisca abdita. All sediments were toxic to the amphipods, while sites PB4A, PB6A, and PB9 were the only sites toxic to mysids. Due to its toxicity to both test organisms, site PB6A was chosen for a marine whole sediment phase I toxicity identification evaluation (TIE). Results of the TIE found toxicity to amphipods was primarily due to nonionic organic contaminants (NOCs), rather than cationic metals or ammonia. Causes of mysid toxicity in the TIE were less clear. An assessment of metal bioavailability using equilibrium partitioning (EqP) approaches supported the results of the TIE that cationic metals were not responsible for observed toxicity in PB6A for either organism. Toxic units (TU) calculated on measured concentrations of NOCs in the sediment yielded a total TU of 1.25, indicating these contaminants are contributing to the observed sediment toxicity. Using a combination of these TIE and EqP assessment tools, this investigation was capable of identifying NOCs as the likely class of contaminants causing acute toxicity to amphipods exposed to Patrick Bayou sediment. The cause of mysid toxicity was not definitively determined, but unmeasured NOCs are suspected.

A comparison of acute and chronic toxicity methods for marine sediments

Sediment toxicity tests are valuable tools for assessing the potential effects of contaminated sediments in dredged material evaluations because they inherently address complexity (e.g., unknown contaminants, mixtures, bioavailability). Although there is a need to understand the chronic and sublethal impacts of contaminants, it is common to conduct only short-term lethality tests in evaluations of marine sediments. Chronic toxicity methods for marine sediments have been developed but the efficacy of these methods is less documented. In this evaluation of marine sediments collected from the New York/New Jersey (NY/NJ) Harbor, three 10-d acute toxicity test methods (Ampelisca abdita, Leptocheirus plumulosus, Americamysis bahia) and three chronic and sublethal test methods (28-d L. plumulosus, 20- and 28-d Neanthes arenaceodentata) were applied by three testing laboratories. Although the N. arenaceodentata and A. bahia tests did not indicate significant toxicity for the sediments tested in this study, these methods have been reported useful in evaluating other sediments. The 10-d A. abdita, 10-d L. plumulosus and 28-d L. plumulosus tests were comparable between laboratories, indicating 29-43%, 29%, and 43-71% of the tested sediments as potentially toxic. The 28-d L. plumulosus method was the only chronic toxicity test that responded to the test sediments in this study. The 28-d L. plumulosus endpoint magnitudes were related to sediment chemistry and the sublethal endpoints were reduced as much or more than acute lethality endpoints. However, intra-treatment sublethal endpoint variability was greater, compromising detection of statistical significance. In this study, the chronic L. plumulosus test method was less consistent among laboratories relative to acute test methods, identifying potential for toxicity in a similar number (or slightly more) NY/NJ Harbor sediments.

Do toxicity identification and evaluation laboratory-based methods reflect causes of field impairment?

Sediment toxicity identification and evaluation (TIE) methods are relatively simple laboratory methods designed to identify specific toxicants or classes of toxicants in sediments; however, the question of whether the same toxicant identified in the laboratory is causing effects in the field remains unanswered. The objective of our study was to determine if laboratory TIE methods accurately reflect field effects. A TIE performed on sediments collected from the Elizabeth River (ER) in Virginia identified polycyclic aromatic hydrocarbons (PAHs) as the major toxicants. Several lines of evidence indicated PAHs were the major toxic agents in the field, including elevated PAH concentrations in ER sediments, comet assay results from in situ caged Merceneria merceneria, and chemical analyses of exposed M. merceneria, which indicated high PAH concentrations in the bivalve tissue. Our final evidence was the response from test organisms exposed to ER sediment extracts and then ultraviolet (UV) radiation. UV radiation caused a toxic diagnostic response unique to PAHs. The aggregation of these various lines of evidence supports the conclusion that PAHs were the likely cause of effects in laboratory- and field-exposed organisms, and that laboratory-based TIE findings reflect causes of field impairment

Passaic river sediment interstitial water phase I toxicity identification evaluation

A suite of tests was conducted to evaluate and identify the cause or causes of toxicity in Passaic River sediments. Sediment toxicity was measured with three types of bioassays: a whole sediment bioassay with the marine amphipod, Ampelisca abdita, and interstitial water bioassays with A. abdita and the bioluminescent bacterium Vibrio fisheri (Microtox((R))). In addition, a Phase I Toxicity Identification Evaluation (TIE) was conducted to elucidate the cause of observed toxicity. Analytical concentrations of selected residues in whole sediment and interstitial water from the five sampling stations were considered in conjunction with the conclusions drawn from the toxicity tests and Phase I TIE results. Finally, a toxic units approach was used to evaluate the predicted toxicity of measured interstitial water residue concentrations. There was a lack of toxic response in the short-term interstitial water bioassays, indicating that oxidants, soluble forms of metals, and dissolved phase neutral organics were not likely toxicants. However, there was significant toxicity indicated by the whole sediment A. abidita bioassays. After 10 days, there was complete or near complete mortality in amphipods exposed to all of the sediment samples tested. Removal of interstitial water toxicity by filtration was common to all four stations that exhibited measurable initial toxicity. The observed toxicity characteristics are consistent with particle associated neutral organics. This conclusion is supported by toxicity removal via filtration, lack of toxicity in the Microtox((R)) assays, and the fact that whole sediments were more toxic than was interstitial water.

Applications of carboxylesterase activity in environmental monitoring and toxicity identification evaluations (TIEs)

This review has examined a number of issues surrounding the use of carboxylesterase activity in environmental monitoring. It is clear that carboxylesterases are important enzymes that deserve increased study. This class of enzymes appears to have promise for employment in environmental monitoring with a number of organisms and testing scenarios, and it is appropriate for inclusion in standard monitoring assays. Given the ease of most activity assays, it is logical to report carboxylesterase activity levels as well as other esterases (e.g., acetylcholinesterase). Although it is still unclear as to whether acetylcholinesterase or carboxylesterase is the most "appropriate" biomarker, there are sufficient data to suggest that at the very least further studies should be performed with carboxylesterases. Most likely, data will show that it is optimal to measure activity for both enzymes whenever possible. Acetylcholinesterase has the distinct advantage of a clear biological function, whereas the endogenous role of carboxylesterases is still unclear. However, a combination of activity measurements for the two enzyme systems will provide a much more detailed picture of organism health and insecticide exposure. The main outstanding issues are the choice of substrate for activity assays and which tissues/organisms are most appropriate for monitoring studies. Substrate choice is very important, because carboxylesterase activity consists of multiple isozymes that most likely fluctuate on an organism- and tissue-specific basis. It is therefore difficult to compare work in one organism with a specific substrate with work performed in a different organism with a different substrate. An attempt should therefore be made to standardize the method. The most logical choice is PNPA (p-nitrophenyl acetate), as this substrate is commercially available, requires inexpensive optics for assay measurements, and has been used extensively in the literature. However, none of these beneficial properties indicates that the substrate is an appropriate surrogate for a specific compound, e.g., pyrethroid-hydrolyzing activity. It will most likely be necessary to have more specific surrogate substrates for use in assays that require information on the ability to detoxify/hydrolyze specific environmental contaminants. The use of carboxylesterase activity in TIE protocols appears to have excellent promise, but there are further technical issues that should be addressed to increase the utility of the method. The main concerns include the large amount of nonspecific protein added to the testing system, which can lead to undesirable side effects including nonspecific reductions in observed toxicity, decrease in dissolved oxygen content, and organism growth. It is probable that these issues can be resolved with further assay development. The ideal solution would be to have a commercial recombinant carboxylesterase that possessed elevated pyrethroid-hydrolysis activity and which was readily available, homogeneous, and inexpensive. The availability of such an enzyme would address nearly all the current method shortcomings. Such a preparation would be extremely useful for the aquatic toxicology community. Further work should focus on screening available esterases for stability, cost, and activity on pyrethroids, with specific focus on esterases capable of distinguishing type I from type II pyrethroids. It would also be beneficial to identify esterases that are not sensitive to OP insecticides. Many esterases and lipases are available as sets to test chemical reactions for green chemistry, enabling large-scale screening. Other potential approaches to increase the utility of the enzyme include derivatization with polyethylene glycol (PEG) or cyanuric acid chloride to increase stability and reduce microbial degradation. It is also possible that the enzyme could be formulated in a sol gel preparation to increase stability. It is likely that the use of carboxylesterase addition will increase for applications in sediment TIEs. Carboxylesterases are an interesting and useful enzyme family that deserves further study for applications in environmental monitoring as well as to increase our understanding of the fundamental biological role(s) of these enzymes. There are, of course, other enzymes that show high esterase activity on pyrethroids but are not technically carboxylesterases in the alpha/beta-hydrolase fold protein family. These enzymes should also be examined for use in TIE protocols and "esterase" arrays as well as for general applications in environmental monitoring. One can envision the creation of a standardized screen of enzymes with esterase activity to (1) identify environmental contaminants, (2) estimate the potential toxic effects of new compounds on a range of organisms, and (3) monitor organism exposure to agrochemicals (and potentially other contaminants). This approach would provide a multibiomarker integrative assessment of esterase-inhibiting potential of a compound or mixture. In conclusion, much is still unknown about this enzyme family, indicating that this area is still wide open to researchers interested in the applications of carboxylesterase activity as well as basic biological questions into the nature of enzyme activity and the endogenous role of the enzyme.

Removal of ammonia toxicity in marine sediment TIEs: a comparison of Ulva lactuca, zeolite and aeration methods

Toxicity Identification Evaluations (TIEs) can be used to determine the specific toxicant(s), including ammonia, causing toxicity observed in marine sediments. Two primary TIE manipulations are available for characterizing and identifying ammonia in marine sediments: Ulva lactuca addition and zeolite addition. In this study, we compared the efficacy of these methods to (1) remove NH(x) and NH(3) from overlying and interstitial waters and (2) reduce toxicity to the amphipod Ampelisca abdita and mysid Americamysis bahia using both spiked and environmentally contaminated sediments. The utility of aeration for removing NH(x) and NH(3) during a marine sediment TIE was also evaluated preliminarily. In general, the U. lactuca and zeolite addition methods performed similarly well at removing spiked NH(x) and NH(3) from overlying and interstitial waters compared to an unmanipulated sediment. Toxicity to the amphipod was reduced approximately the same by both methods. However, toxicity to the mysid was most effectively reduced by the U. lactuca addition indicating this method functions best with epibenthic species exposed to ammonia in the water column. Aeration removed NH(x) and NH(3) from seawater when the pH was adjusted to 10; however, very little ammonia was removed at ambient pHs ( approximately 8.0). This comparison demonstrates both U. lactuca and zeolite addition methods are effective TIE tools for reducing the concentrations and toxicity of ammonia in whole sediment toxicity tests.

Pore water testing and analysis: the good, the bad, and the ugly

The increasingly common practice of collecting and assessing sediment pore water as a primary measure of sediment quality is reviewed. Good features of this practice include: pore water is a key exposure route for some organisms associated with sediments; pore water testing eliminates particle size effects; pore water analyses and tests can provide useful information regarding contamination and pollution. Bad features include: pore water is not the only exposure route; pore water tests lack chemical or biological realism: their "sensitivity" relative to other tests may be meaningless due to manipulation and laboratory artifacts; many sediment and surface dwelling organisms are not directly influenced by pore water. Bad features can become ugly if: other exposure pathways are not considered (for toxicity or bioaccumulation); manipulation techniques are not appropriate; pore water tests are inappropriately linked to population-level effects. Pore water testing and analyses can be effective tools provided their limitations are well understood by researchers and managers.