M3 AM Ecological Risk Assessment (Part 1)|
Monday, 14 November 2005: 8:00 AM - 11:40 AM in Ballroom 3
19 (GEN-1117-801130) Ecological Significance of the Exxon Valdez Oil Spill.
Start time: 8:00 AM
Harwell, M1, Gentile, J2, 1 Harwell Gentile & Associates, LC, Palm Coast, Florida, US2 Harwell Gentile & Associates, LC, Cape Cod, Massachusetts, USA
The ecological risk assessment framework is used to assess the current ecological significance of risks to Prince William Sound (PWS), Alaska, from the Exxon Valdez oil spill (EVOS) after 15 years. Criteria to assess ecological significance include whether a change in a valued ecosystem component (VEC) is sufficient to affect the structure, function, and/or health of the system and whether such a change exceeds natural variability. EVOS occurred on 24 March 1989, releasing over 250,000 barrels of crude oil into PWS. Because PWS is highly dynamic, the residual oil was largely eliminated in the first few years, and now only widely dispersed, highly weathered or isolated small pockets of residual sources remain. Many other sources of PAHs exist from past or present human activities or natural seeps. Multiple-lines-of-evidence analyses indicate residual PAHs from EVOS no longer represent a significant ecological risk to PWS. To assess the ecological significance of any residual effects from EVOS, we examined the extensive literature on more than 20 VECs, including primary producers, filter feeders, fish and bird primary consumers, fish and bird top predators, a bird scavenger, mammalian primary consumers and top predators, biotic communities, ecosystem-level properties of trophodynamics and biogeochemical processes, and landscape-level properties of habitat mosaic and wilderness quality. None of these has any ecologically significant effects at present, with the possible exception of one pod of orcas and one subpopulation of sea otters; however, in both those cases, PWS-wide populations have fully recovered. Many other stressors continue to affect PWS adversely, including climate and oceanographic variability, increased tourism and shipping, invasive species, the 1964 earthquake, and over-exploitation of marine resources, with associated cascading effects on populations of PWS fish and predators, but the ecosystems of PWS have now recovered from EVOS.
20 (ZWI-1117-773778) Mink and PCDD/Fs in the Tittabawassee River basin.
Start time: 8:20 AM
Zwiernik, Matthew1, Moore, Jeremy1, Tazelaar, Dustin1, Kay, Denise2, Hamman, David1, Blankenship, Alan 2, Giesy, John1, 1 National Food Safety and Toxicology Center, Center for Integrative Toxicology,Zoology Department, Michigan State University, East Lansing, MI, United States2 Entrix, Inc, Okemos, MI, United States
The Tittabawassee River, located in central Michigan, USA, contains polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the sediments, floodplain soils, and biota downstream of the city of Midland. Mink (Mustela vision) as top predators and year round residence of the river basin have a high potential for exposure. Their sensitivity to adverse effects from this class of compounds makes them of special concern. An ongoing risk of harm evaluation for these animals utilizes a multiple line of evidence approach. Measurement endpoints include dietary and tissue based exposure assessments as well as population health criteria including population demographics, nutritional state and reproductive potential. Concentrations of seventeen 2,3,7,8 PCDD and PCDF congeners were measured in dietary items including composite samples of forage fish, and crayfish, as well as individual small mammals, all collected from multiple locations within the floodplain both upstream and downstream of Midland. Total 2,3,7,8-PCDD/DF concentrations of reference area dietary items ranged from 4.06 to 5.06 ng/kg wet weight (n=2), 2.15 to 2.39 ng/kg ww (n=2) and 1.48 to 530 (n=34) ng/kg ww respectively while target area dietary items exhibited total PCDD/DF concentrations ranging from 200 to 610 ng/kg ww (n=5). 86.3 to 1280 ng/kg ww (n=8) and 10.6 to 12700 (n=136) respectively. Additionally, 32 adult mink have been sampled from the site including 18 reference and 14 target area mink. All female mink of reproductive age presented placental scaring regardless of location. Mink mean body weights for both males and females were slightly greater for target area mink, 917.06 g and 517.38 g respectively vs. 871.55 and 482.29 for reference area mink. Overall nutritional state followed this same pattern with target mink receiving slightly higher scores ranging from good to excellent. Additional data will include brain to liver weight relationships and a dietary exposure assessment based on both a literature and site-specific dietary composition.
21 (PFI-1117-750458) Relative Risk Assessment of the Androscoggin River Watershed in Maine and New Hampshire.
Start time: 8:40 AM
Pfingst, Amanda1, Chen, Valerie1, Landis, Wayne1, 1 Institute of Environmental Toxicology, Huxley College of the Environment, Western Washington University, Bellingham, WA, USA
A regional risk assessment is being conducted for the Androscoggin River Watershed in Maine and New Hampshire, using the Relative Risk Model of Landis and Weigers. This large watershed supports industry, agriculture, forestry, recreation, residential communities and much wildlife, including many threatened/endangered species. Assessment endpoints were determined after meeting with stakeholders. The stakeholders represent large and small businesses, industry, governments, non-profits and citizens. Efforts were made to choose measurable entities that represent the values that such parties hold in the watershed. Sources of stress to endpoints include, but are not limited to, three pulp and paper mills, 30 dams, logging, agricultural runoff, development/urbanization, and atmospheric mercury deposition from industry in the Midwest. The watershed was divided into sub-regions to better characterize risk. The conceptual model, results, and uncertainty analysis for sub-regions 1-6 are presented in this poster. These sub-regions cover the Androscoggin River from its headwaters in Errol, NH to the Gulf Island dam near Lewiston, ME. Continuing research on the remaining sub-regions, from Lewiston to the end of the river in Merrymeeting Bay, is also presented. This research includes characterization of the lower watershed, additions to the conceptual model and risk results, and uncertainty reduction.
22 (JOH-1117-765772) Use of the SPMD-TOX paradigm for toxicological risk assessment of urban streams in six major metropolitan areas of the United States.
Start time: 9:00 AM
Johnson, B1, Goodbred, S2, Huckins, J1, 1 USGS, Columbia Environmental Research Center, Columbia, MO, USA2 USGS, Sacramentp, CA, USA
Toxicological risk assessments to determine the effects of urban land-use on aquatic communities in six major metropolitan areas in the United States were conducted as part of the National Water Quality Assessment (NAWQA) program effects of urbanization on stream ecosystems (EUSE) study. Managing aquatic resources in rapidly developing urban areas though out the U.S. is becoming a challenge. One hundred and sixty sites in urban streams, from MidAtlantic, Midwestern, Southern, and Western states were monitored over 30-day periods for the bioavailability of hydrophobic organic contaminants. Toxicological risk assessments were made using the SPMD-TOX paradigm: semipermeable membrane devices (SPMD) to collect and concentrate bioavailable aquatic contaminants in situ and short-term microscale toxicity tests (TOX) -- Fluoroscan, Microtox, Mutatox, and three direct small scale invertebrate tests -- to detect waterborne bioavailable ecotoxins. SPMD-TOX assessment clearly indicated that hydrophobic contaminants and potential toxicity increase in streams as urban intensity increases in all six major metropolitan areas. Hot spots or areas of concern for the resource managers were also identified and may be caused by specific point sources of pollution. SPMD-TOX was a sensitive, technically simple, and cost-effective tool to monitor and assess urban streams for chemical contaminants that may adversely affect aquatic communities and water quality.
(58202) Morning Break.
Start time: 9:20 AM
23 (HIN-1117-637871) Piscivorous Wildlife Risk Assessment: Evaluations based on a national monitoring program.
Start time: 10:00 AM
Hinck, J1, Tillitt, D1, 1 USGS-Columbia Environmental Reseach Center, Columbia, Missouri, USA
The Large River Monitoring Network (LRMN) of the BEST Program has measured organochlorine and elemental concentrations in fish from large river basins throughout the U.S. including the Mississippi, Rio Grande, Columbia, Yukon, and Colorado. Potential contaminant sources such as urban and agricultural runoff, industrial discharges, mine drainage, and irrigation varied among the sampling sites. Birds and mammals may be exposed to contaminants through the fish they consume from these sites; however, an assessment of potential risks to piscivorous wildlife has not been conducted. Allometric relationships, consumption rates, and other species-specific metrics of exposure models were estimated for selected mammalian and avian wildlife. Exposure and subsequent hazard evaluation models were developed for such species as mink, Northern river otter, bald eagle, Great blue heron, and belted kingfisher. Toxicity reference values (TRVs), which were derived from chemical specific effects on reproductive performance, growth, and survival in a species, were determined for each chemical and species combination. Hazard quotients (HQs) were then calculated by comparing the expected environmental concentrations (EEC) in a species, developed from fish concentrations and the species-specific exposure models, with the TRVs (HQ = EEC/TRV). The HQs indicted which contaminants pose a risk to piscivorous wildlife and which sites warrant further investigation.
24 (COH-1117-833306) Amphibian Risk Assessment, Risk Management, and Habitat Conservation for Golf Course Developments.
Start time: 10:20 AM
cohen, s1, klemens, m2, klein, m3, 1 environmental & turf services, inc., wheaton, md, usa2 wildlife conservation society, bronx, ny, usa3 environmental planning services, west hartford, ct, usa
There is a general consensus that amphibian populations are in a state of worldwide decline, and there is anecdotal evidence that the rate of deformities is increasing. Pesticides and fertilizers are among several possible causes cited for the increased rate of declines and deformities, although a cause-effect relationship has not been established, except for habitat destruction as a significant cause of population decline. Golf courses, which regularly receive pesticide and fertilizer applications, can be home to a variety of wildlife, including amphibians. Golf course developments often have the potential to be suitable sites for amphibian habitats because their large areas frequently couple prime upland habitat with wetlands and other surface water bodies. The planning of golf course developments, especially those that include housing, requires an integrated and interdisciplinary approach to ensure that the development and the environment can coexist. The first step is to characterize the water resources, identify potential amphibian habitats, and identify and characterize amphibian populations on the proposed site. The next step is to rank the habitats – typically vernal pools associated with wetland systems – according to their productivity and species diversity. Concurrently, two-part development envelopes should be drawn around each priority habitat that provide total protection for 100 ft (30.4 m) and minimal disruption for 750 ft (228 m). The rankings and the protection envelopes should be used to guide the development of the site plan. The third step is to conduct a pesticide and fertilizer risk assessment based on computer modeling estimates of exposure to the larvae in the aquatic phase, as well as dermal exposure to juveniles and adults in the terrestrial/upland phase. Amphibian toxicology studies are not required by regulatory agencies, therefore we developed a methodology to calculate maximum allowable concentrations (MACs) for amphibian exposure to turf pesticides, as well as nitrates. The final step is to integrate this information into a risk management program, which can include turf management, civil engineering, and design mitigation measures. A case study of a proposed development in coastal Connecticut will be presented.
25 (HAR-1117-823333) Evaluating Risk of Essential and Biologically Important Substances.
Start time: 10:40 AM
Harrass, M1, 1 Rio Tinto Borax, Valencia, California, US
Hazard characterization describes what adverse effects are associated with exposures to substances of concern. The relevant information is typically displayed as an S-shaped curve, showing how the frequency of effects increases as exposure increases. Typically the curve is assumed to pass through the origin, i.e., no adverse effects at zero exposure. However, for substances that are essential or biologically important, deficiencies may result in an increasing incidence of adverse effects as exposures decrease. For such substances, the exposure/response pattern is a U-shaped distribution, with adverse effects increasing as exposures approach zero. Standard approaches to risk characterization do not easily accommodate a U-shaped distribution of effects. For example, a PNEC is typically calculated using divisors (application factors or uncertainty factors) and a selected point along the toxicity distribution. Such values may be below exposures where adverse effects due to deficiency occur. Several modifications of hazard characterization and risk characterization may be considered. One option is to ignore adverse effects due to deficiency during hazard characterization and perhaps address deficiencies when considering risk management options. A second is to incorporate total risk into the derivation of an endpoint, e.g. to explicitly consider risk of deficiency as well as risk of toxicity. A third approach is to modify selection of the application or uncertainty factor to reflect the range between regions of toxicity and regions of deficiency. Boron, known to be essential for plants and some animals while also being toxic at higher concentrations, will be used to illustrate these approaches.
26 (BEL-1123-267692) Risk Overview of a New and Advanced Global Environmental Assessment of Alcohol Ethoxylate Surfactant Mixtures.
Start time: 11:00 AM
Belanger, S1, Boeije, G2, Cano, M3, Dorn, P3, Eadsforth, C4, Federle, T1, Gumbel, H4, Marshall, S5, Morrall, S1, Toy, R7, 1 Procter & Gamble Company, USA2 Procter & Gamble, Brussels, Belgium3 Shell Global Solutions, USA4 Shell Global Solutions, UK5 BASF, Ludwigshafen, Germany7 Shell Chemicals, Ltd., UK
Alcohol ethoxylates (AE), a class of nonionic surfactants, are produced at >1 million metric tons/year globally. Commercial alcohol ethoxylate surfactants are mixtures that range from 12 to 18 alkyl carbons with varying degrees of ethylene oxide (ethoxylate) substitution that range from no (zero) to 18 units per molecule. Risk assessments conducted in the 1990's in both Europe and the US were updated based on collective advancements in analytical methods, ecotoxicology and environmental fate studies and data analysis techniques. The environmental fate and effects of AE are linked to the pattern (environmental fingerprint) of the AE homologue distribution in a mixture. New analytical methods enable detailed understanding of the distribution of AE homologues in sewage treatment plant effluents at sub-part-per-billion levels (ng/L). These methods were deployed in waste water treatment plant effluent monitoring studies across Europe, Canada and the USA. Fate studies were performed to understand sorptive behavior of AE in effluents and receiving waters. Evaluations using benchtop sewage treatment plant test systems and batch die-away studies provided detailed insight into metabolism of AE and its short-lived intermediates. Chronic toxicity QSARs for algae, invertebrates and fish from laboratory and stream mesocosm studies were developed to allow quantitative interpretation of the relationships between commercial mixtures and actual environmental distributions. Using species sensitivity distributions to estimate PNECs for each homologue, and then applying a concentration addition approach, we calculated a toxic unit fraction for individual AE homologues. These were then summed to obtain the toxic unit fraction for the whole effluent distribution as a descriptor for the risk potential of AEs. Collectively, the application of cutting edge technology has resulted in an updated global environmental risk assessment of AE. This process re-affirmed the very low risk of AE to aquatic life in all monitored geographies.
27 (ARN-1117-740007) A screening level risk assessment model for chemical fate and effects in the environment.
Start time: 11:20 AM
Arnot, J1, Mackay, D1, Webster, E1, Southwood, J2, 1 Trent University, Peterborough, ON, Canada2 Golder Associates, Ottawa, ON, Canada
A screening level risk assessment model is developed and described that seeks to assess and prioritise chemicals by estimating environmental fate and transport, bioaccumulation and exposure to humans and wildlife for a unit emission rate to identify the most sensitive risk endpoint. A critical emission rate is then calculated as a result of that endpoint being reached. Finally, an estimated emission rate is compared with the critical emission rate as a risk assessment factor. This "back tracking" process avoids the use of suspect emission rate data as model input. To illustrate its applicability the model is applied to four chemicals for detailed discussion and to a group of 70 chemicals drawn from the Canadian Domestic Substances List. It is shown that both the simple Level II and the more complex Level III models can be used to "bin" substances into categories of similar probable risk. The model brings together information on chemical partitioning, reactivity, environmental fate and transport, bioaccumulation, exposure, objective or effect levels and emission rates in a coherent system for assessing risk at a screening level. It is hoped that the approach may be useful for identifying and prioritising those chemicals of commerce that are of greatest potential concern. Following such an assessment, selected chemicals can be more fully and accurately evaluated using monitoring data in conjunction with models describing chemical fate and effects in more detail in real regional environments and food webs.