Spotlight On: Environmental Toxicology

Our toxicologists design, implement, conduct and manage a wide range of laboratory and field-based bioassays, investigations and other tests to fill key data gaps and increase our understanding of the adverse effects of chemicals, mixtures, and other stressors on numerous organisms, including bacteria, algae, invertebrates, fish, reptiles, birds, and mammals.

We utilize our in-house expertise, as well as our strategic collaborations and partnerships with university, private, federal, and state laboratories, to determine the toxicity of a wide range of contaminants under varying conditions while applying state-of-the-art toxicity metrics. We offer a holistic approach to assessing toxicity that includes a range of endpoints including standard, molecular, physiological, and behavioral metrics aimed at interpreting how contaminants and other stressors adversely affect plants and animals in the environment.

• Evaluation of the toxicity of major organic and inorganic contaminants (e.g., crude oil and derivatives, metals, metalloids, PCBs, PFAS, pesticides, etc.)

• Multiple stressor evaluations that include contaminants and/or other stressors such as UV light, temperature, and dissolved oxygen

• Standardized toxicity testing according to published protocols

• Customized project or site-specific toxicity testing

In addition to theoretical and applied research into the mechanisms and toxic effects of contaminants, we have extensive experience applying our expertise to practical problems such as regulatory standard setting, the development of adverse effects thresholds and response models, extrapolating laboratory observations to the field, expert testimony, ecological risk assessments, and natural resource damage assessments.

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Bristol Bay supports the largest commercial sockeye salmon fishery in the world, and also an important subsistence fishery for native communities. Abt designed and conducted bioassays using two model fish species (rainbow trout and fathead minnows) in close collaboration with Colorado Parks and Wildlife, using site water from the watershed and reconstituted laboratory water with similar properties to conduct a series of tests to evaluate the soundness of existing and alternative water quality criteria (hardness-criteria and Biotic Ligand Model derived criteria). As a follow-on study, Abt collaborated with the University of Alaska Fairbanks and conducted additional acute copper bioassays on sockeye, Chinook, and coho salmon fry using water collected from the field. We also conducted behavioral assays to investigate olfactory inhibition with copper exposure on rainbow trout, sockeye and coho salmon. Our research demonstrates that current copper criteria standards used by the state of Alaska and other states may not be sufficient to protect salmon in the Bristol Bay watershed.

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Warming water temperatures and altered hydrographs due to climate change can shift the timing of salmon embryo hatch and larval emergence. Shifts in timing of these developmental milestones can result in mismatched occurrence of critical resources when larvae need to begin feeding. Mismatched timing may also expose larval salmon to adverse flow conditions due to altered hydrographs. These and other stressors may contribute to decreased survival and reductions in salmon recruitment. Our research is focused on generating comprehensive developmental data under incubation temperatures salmon experience in natural spawning sites to improve the underlying data used to model the impacts of climate change on salmon reproduction. We are currently designing and testing novel in-situ monitoring systems that track sockeye salmon development and incubation temperatures in natural spawning sites in the Bristol Bay Watershed and conducting complementary laboratory work in collaboration with the University of Alaska Fairbanks and Colorado Parks and Wildlife.

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Abt has more than 25 years’ experience investigating the toxicity of metals to fish, aquatic invertebrates, birds and other wildlife. This work includes identifying the fate and transport of metals in impacted environments and biogeochemical influences on metal concentrations and diel metal cycling in aquatic environments. Our research also includes laboratory and field assays designed to determine the fate and transport as well as the waterborne and dietary toxicity and associated modes of action of several metals and metalloids associated with mining activities including arsenic, cadmium, cobalt, copper, lead, nickel and zinc. Additionally, we have conducted associated research on the influence of water quality (e.g., anions, cations, alkalinity, pH, and organic carbon) on metal toxicity and evaluated various regulatory guidelines and approaches to assessing toxicity under a range of environmental and chemical conditions.

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As part of Abt’s larger portfolio of PFAS-related research, Abt has conducted extensive field work collecting soil, water, sediment, invertebrate, fish, bird and mammal samples and conducted laboratory studies to investigate PFAS uptake into the food web and subsequent biomagnification. This work has focused on PFOA, PFOS and GenX and included uptake into coniferous and deciduous trees, several freshwater fish and invertebrates, white-tailed deer and loons. Our laboratory work focused on PFAS uptake from sediment to invertebrates and fish and was conducted with the University of North Texas.

• National Oceanic and Atmospheric Administration (NOAA)
• US Fish and Wildlife Service (USFWS)
• State of Louisiana

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The Deepwater Horizon (DWH) oil spill was of national significance, exposing and injuring natural resources in many areas of the northern Gulf of Mexico. As a result, natural resource trustees (e.g., state and federal agencies) initiated a natural resource damage assessment (NRDA). As part of the assessment, Abt assisted with assessing the exposure to contaminants such as oil and dispersant, injuries resulting from that exposure, and compensation (damages) for restoration. Abt also designed, directed, and managed the Trustee’s aquatic toxicity testing program and served as one of the Principal Investigators for this program as well as for the USFWS avian toxicity testing program. These programs have included 30 university, federal, state and private laboratories conducting research and analysis on the toxicity of oil, dispersant and their effects on 40 different phytoplankton, invertebrate, fish, reptile and bird species. Toxicity test data have been coupled with analytical chemistry data to aid in determining and quantifying injuries to a variety of marine, animal and plant life exposed to oil. We completed over 650 definitive bioassays and chemical characterizations of oil and dispersant in water and sediment and created a comprehensive database with these data (see NOAA's DIVER DWH Toxicity Testing Database). Abt also played a key role in authoring many sections of the DWH Programmatic Damage Assessment and Restoration Plan (PDARP) in close collaboration with NOAA and USFWS and authored several supporting technical appendices.

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Photo-induced toxicity of crude oil occurs when ultraviolet light (UV) contacts certain photo-active polycyclic aromatic hydrocarbons (PAHs). These PAHs set off chain reactions that cause cell and tissue damage, and results in death and other sublethal effects. There are at least 14 PAHs in crude oil that are known to be photo-active, and our recent work indicates that photo-activation increases toxicity by 10-100 times. In collaboration with Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the University of North Texas, we investigated photo-induced toxicity of crude oil from Australia’s North West Shelf (NWS) on two species of native fish at the Indian Ocean Marine Research Centre in Perth, Australia. Our laboratory tests determined that exposure to NWS oil and UV results in photo-induced toxicity through both photo-sensitization and photo-modification.

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Abt led the design, development and testing of an in-situ toxicity testing apparatus designed to assess toxicity of oil or chemical spills to small invertebrates or early life stage fish. The team, including researchers from Abt, the University of North Texas and Water Mapping, conducted onsite testing of the apparatus at the Coal Point natural oil seeps off the coast of Santa Barbara, CA as well as several tests in freshwater environments. The system allows for real-time toxicity testing of contaminants at the surface or at depth that include other natural stressors such as temperature, dissolved oxygen and UV radiation.

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Abt has led a collaborative effort to determine several adverse effects to zebrafish exposed to PCBs (primarily Aroclor 1254) as embryos. Our team included researchers from NOAA, University of North Texas, University of California Riverside, and Oregon State University. This research applied a wide range of comprehensive toxicological strategies that included: high-throughput screening; RNA-sequencing; early life stage developmental, cardiac and neurological assessments; and grow-out, reproduction and behavioral assays. Another novel aspect of this research included determining embryonic PCB tissue burdens that correlate to a range of toxicological endpoints.

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Abt supported Trustees as part of the Portland Harbor Natural Resource Damage Assessment on many aspects, including the injury assessment. Abt designed, implemented and managed a suite of sediment bioassays on Pacific lampreys, in close collaboration with Oregon State University, the Confederated Tribes of the Siletz Indians, and the US Fish and Wildlife Service. This work included collecting contaminated and reference sediment from the Willamette River, which was used to conduct a series of bioassays examining the effects of various contaminant mixtures on ammocoete survival, growth and behavior. This program also included detailed methods development for conducting work with this unique species/life stage.