bluuebunny/crossref_metadata_2025 huggingface dataset:
Inclusion Ratings: Past, Present, and Future
Authors: Vander Voort GF
Published: March 2009

Chart-based techniques, such as ASTM E 45, have been used to rate inclusion types and content for more than half a century. Chart ratings are subject to considerable error, reproducibility among raters is poor, and they lack precision for today's steels with very low inclusion contents. Image analysis procedures, using ASTM E 1122, where the rating system has been modified to generate improved JK-chart ratings, are now being used widely. A new, alternate approach using stereological relationships for inclusion measurements is given by ASTM E 1245. In this method, the inclusions are separated by type (oxide vs. sulfide usually) and the volume fraction, number per unit area, average length, average area, and spacing are determined. E 1245 is easy to do by image analysis and is fast. In this paper, heats of 52100 bearing steel, made by different technologies, were rated using the current E 45/E 1122 method and by the method of the future, E 1245. The greater merit of the E 1245 method was demonstrated statistically by comparing the test results for the steels made by the different procedures.
Rolling Contact Fatigue Behavior of Heat Resistant Bearing Steels at High Operational Temperatures
Authors: Böhmer H-J , Hirsch T , Streit E
Published: March 2009

An approach was made to estimate the endurance limit in rolling contact fatigue in dependence of the operational conditions for the bearing steels M50 (AMS 6491), M50 NiL (AMS 6278) and the nitrogen-alloyed Cronidur 30 (AMS 5898) by investigating the changes in the residual stress profiles after 5 million cycles of overrolling. Real main shaft bearings with a pitch diameter of 168 mm have been tested. To simulate the heat generated in the turbine engines even under boundary operational conditions oil inlet temperatures between 80° and 210°C have been applied, the rotational speed has been varied between 2500 and 14000 r/min and the interference fit has been changed to produce different hoop stress levels.
A New Type of Flaking Failure in Bearings for Electrical Instruments of Automotive Engines
Authors: Tamada K , Tanaka H , Tsushima N
Published: March 2009

The higher transmission efficiency of engine accessory drive belts has resulted in a new type of bearing damage, called “brittle flaking”. The type of grease used in the bearing was found to have a significant effect on the occurrence of brittle flaking. Thus, brittle flaking can be avoided by using specific greases. The amount of hydrogen measured in the inner rings, outer rings and balls of bearings run under acceleration-deceleration tests, was highest in the stationary ring, where brittle flaking was likely to occur. Brittle flaking was reproduced in rolling contact fatigue tests when the test specimens were charged with a sufficient amount of hydrogen prior to testing. The test results concluded that brittle flaking is caused by the diffusion of hydrogen into the steel due to the decomposition of the grease by a tribochemical reaction.
Bearing Steels 20/20 — A Steelmaker's View Point — A Look Back 20 Years and a Look Forward 20 Years
Authors: Glasgal BM
Published: March 2009

Historically, bearing steels have been manufactured using “clean steel technology” to produce a product that has reduced levels of non-metallic inclusions. Included in this review are the key steel production practices that have evolved over time to make steels with superior cleanliness. The evolution of steelmaking practices over the past twenty years has also given rise to more discriminating test and evaluation methods. The types of testing reviewed here include microscopic examination, oxygen analysis, and various types of fatigue testing. Further improvements in steelmaking technology in the future, such as the increased usage of continuous casting, are expected to result in further quality improvements.
Simulation of Heat Treatment Response and Distortion of Bearing Steels
Authors: Thuvander A , Höglund L , Melander A , From A , Jonsson S , Ågren J , Ölund P , Andersson J-E , Lund T , Beswick J , Slycke J
Published: March 2009

The present paper is a review of recent results on simulation of heat treatment response of bearing steels. Two aspects are considered namely firstly the evolution of the microstructure during heat treatment, especially the carbide structure and the corresponding distribution of alloying elements in the austenite around the carbides. This information is important in order to understand the hardening response of the steel. The analysis is based on thermodynamics and kinetics of multi component systems. Both single carbide sizes and realistic size distributions are considered. Secondly the evolution of the residual stresses and the distortion is considered during the full heat treatment cycle including heating and cooling. These latter simulations focus on the behaviour of full components. Special interest is devoted to origins of out of roundness of bearing rings. Factors like original geometrical imperfections, residual stresses from mechanical manufacturing steps, segregation and uneven cooling action during quenching are considered.
New Steels Now in Use for Automotive Rolling Element Bearings
Authors: Tsushima N , Maeda K , Nakashima H , Kashimura H
Published: March 2009

With the development of clean steels, the influence of retained austenite on the rolling contact fatigue (RCF) life has changed. Under clean oil lubrication, the favorable influence of retained austenite disappeared. Utilizing this phenomenon, a long life material for high temperature was developed with the use of the element Si which improves the heat resistance of steel. With the continuous casting becoming common steel making process, alloying elements should better be minimized because they cause segregation. From this point of view, a medium carbon through hardening steel which has competing RCF life with SUJ2 was developed. Under debris contaminated lubrication, retained austenite has ever favorable effect on RCF life. For these reason, surface modification is important. Long life bearings under debris contaminated lubrication were developed by carbonitriding a through hardening steel or a carburizing steel, respectively.
The New Low Nitrogen Steel LNS — A Material for Advanced Aircraft Engine and Aerospace Bearing Applications
Authors: Berns H , Ebert F-J , Zoch H-W
Published: March 2009

Development tendencies for future aircraft jet engines require new design concepts for rolling element bearings because of an overall increase of loads, temperatures, rotational speeds and the use of new high temperature lubricants.

This paper reviews some of the key parameters which in the past led to the development and application of the known aircraft bearing steels such as M50, M50 NiL and recently Cronidur 30®(AMS 5898). The performance limits of the currently used aerospace bearing steels and the increasing demands on bearing performance for future aerospace applications gave the impact to the design of a new corrosion resistant steel grade of the nitrogen alloyed type, which is suitable for case hardening by nitrogen — the so called “Low nitrogen steel (LNS)”.

The development of the alloy (U.S. pat. 5,503,797), the attainable properties and the corresponding heat treatment process are presented. Achievable hardness, case depth, residual stress pattern and corrosion resistance prove the new “LNS” to be a promising candidate for the next generation of aircraft engine bearings and for advanced, integrated bearing-gear-shaft design concepts.
High Temperature Aircraft Turbine Engine Bearing and Lubrication System Development
Authors: Grant DH , Chin HA , Klenke C , Galbato AT , Ragen MA , Spitzer RF
Published: March 2009

Results are reported for a project sponsored by the United States Air Force Wright Laboratories entitled “High Temperature Bearing / Lubricant System Development.” The major emphasis of this project was the evaluation of bearing materials with improved corrosion resistance, high hot hardness, and high fracture toughness, intended to meet the requirements of the Integrated High Performance Turbine Engine Technologies (IHPTET) Phase II engine. The project included material property studies on candidate bearing materials and lubricants which formed the selection basis for subscale and full-scale bearing rig verification tests. The carburizing stainless steel alloy Pyrowear 675 demonstrated significant fatigue life, fracture toughness, and corrosion resistance improvements relative to the M50 NiL baseline bearing material. The new Skylube II (MCS-2482) lubricant provided significant thermal degradation improvements with respect to the Skylube 600 (PWA-524, MIL-L-87100) lubricant. Two 130 mm bore Pyrowear 675 hybrid ball bearings with silicon nitride balls were run successfully for 231 hours with Skylube II lubricant at temperatures consistent with IHPTET II requirements.
Progress in Bearing Performance of Advanced Nitrogen Alloyed Stainless Steel, Cronidur 30
Authors: Trojahn W , Streit E , Chin HA , Ehlert D
Published: March 2009

The bearing rig tests performed in this study demonstrate superior bearing performance of Cronidur 30 steel over conventional bearing steels. In these tests the L10 life of Cronidur 30 steel as calculated by the DIN/ISO 281 method was 80 times the unfactored L10 life under full lubrication conditions. In boundary lubrication conditions, the Cronidur 30 steel demonstrated the L10 life capability typical of EHD lubrication conditions, whereas the other steels showed drastically reduced lives. In tests with predamaged races and boundary lubrication conditions, Cronidur 30 demonstrated 8 times the calculated L10 life, whereas the conventional steels exhibited further reduce in lives. The improved performance of Cronidur 30 steel over conventional bearing steels is attributed to its unique compositional formulation and microstructure that results in provision of balanced properties in the alloy — hardness, toughness, and corrosion resistance.
The Evaluation of Corrosion Resistant Rod End Rolling Element Bearings
Authors: Braza JF , Giuntoli K , Imundo JR
Published: March 2009

Recent developments on carburizing grades of stainless steels [1–3] have provided new materials to produce corrosion resistant airframe control bearings. This paper presents the application of one of these new carburizing grades of stainless steel to rod end ball bearings. The outer ring of the rod end bearing is made out of carburized stainless steel, while the inner ring and balls are made out of through-hardened stainless steel. The stainless steel rod end bearings were evaluated according to various ASTM and Military specifications for performance and corrosion resistance. The stainless steel rod end bearings exceeded the performance requirements of standard rod end bearings (which are comprised of a carburized 8620 steel outer ring and 52100 steel inner ring and balls) in accordance with MIL-8-6039. The rod end bearings were evaluated in the radial fracture load, axial fracture load, and radial dynamic load tests. Also, salt spray and alternate immersion corrosion tests (ASTM B 117-85 and G 44-88, respectively) were conducted on the stainless steel rod end bearings. The stainless steel rod end bearings exhibited superior corrosion resistance to the standard 8620/52100 steel rod end bearings.
Rolling Contact Fatigue Properties of TIN/NBN Superlattice Coatings on M-50 Steel
Authors: Liston M-JA
Published: March 2009

A superlattice coating (TiN/NbN) was evaluated and shown to successfully increase the rolling contact fatigue (RCF) performance of M-50 steel when tested on the Ball/Rod RCF tester at 3.4 GPa contact stress and a lambda condition of 0.7. The L10 life of the M-50 steel improved from 2 to 10 times when coated with the TiN/NbN superlattice coating. Lives of the coated M-50 specimens varied depending on the approximated thickness of the individual coating layers. Thinner layers resulted in better RCF performance. The superlattice coating consisted of alternating layers of TiN and NbN, deposited using an unbalance magnetron sputtering system. Due to the two fold symmetry of the cylindrical samples, the individual layers were not deposited in perfectly distinct layers.
Occurrence and Distribution of Semivolatile Organic Compounds in Stream Bed Sediments, United States, 1992–95
Authors: Lopes TJ , Furlong ET , Pritt JW
Published: March 2009

Bed-sediment samples from streams were collected from 443 sites in 19 major river basins during 1992–95 and analyzed for semivolatile organic compounds (SVOCs) to assess the occurrence and distribution of selected hydrophobic contaminants. Forty SVOCs were detected in more than 5 percent of samples. Of these 40 SVOCs, 27 were polycyclic aromatic hydrocarbons (PAHs), 5 were azaarenes, 5 were phthalates, 2 were phenols, and 1 was a quinone. Statistically higher concentrations of the sum of PAHs, azaarenes, and phthalates were measured in samples from urban drainage basins in comparison to other land uses. The frequency of detection and concentrations of PAHs, azaarenes, and phthalates were highest in the northeastern part and lowest in the western part of the United States. Concentrations of the sum of PAHs and sum of phthalates had statistically significant, but weak, correlations with toxic releases to air, population density, and urban land use. Urban activities could be significant sources and the atmosphere could be a significant transport mechanism affecting the distribution of certain SVOCs.
Experiences with EPA's Proposed Screening Analyses for Bioconcentratable Compounds
Authors: Louch JR , LaFleur LE , Woodrow DM , Wilson GR
Published: March 2009

EPA has proposed screening analyses for the identification of unknown, potentially bioconcentratable chemicals in effluent and sediment, and for determining tissue residues. As part of an EPA-sponsored round robin study, NCASI analyzed effluent, tissue, and sediment samples following EPA's procedures. NCASI's results suggest that surrogate recovery criteria can be met and that volatilization can be a significant factor leading to low recoveries; results also suggest that the specified tissue and sediment cleanups are simply not rugged enough to deal with all samples. To more thoroughly characterize the efficacy of the methods, NCASI also undertook laboratory evaluations of the proposed effluent and tissue screens using a suite of chemicals representing a wide range of chemical moieties. Results from these experiments demonstrate that the effluent analysis gives a greater rate of false negatives than the tissue analysis, where a false negative is the non-detect of a bioaccumulative chemical. In addition, the effluent and sediment screens are shown to be subject to false positives and negatives arising from the specified acid celite cleanup. Overall, the proposed analyses cannot be considered effective tools for assessing bioconcentration potential in complex matrices.
Comparison of LC50 Results from Commonly Used Computer Programs
Authors: Sebaugh JL
Published: March 2009

Using 50 data sets, this paper compares LC50s computed by several, commonly used computer programs. Programs evaluated include: Stephan, TOXSTAT®, ToxCalc™, U.S. Environmental Protection Agency (PROBIT and TSK), and this author's SAS® program. Numeric comparisons are made of both the LC50 estimate and its 95% confidence limits. An evaluation was made of the robustness of the programs to unusual data sets, the ease of use, and the clarity with which the programs provide results or error messages. The SAS LC50 program provided estimates for the greatest number of data sets. The probit LC50 point estimates provided by the EPA program and the SAS LC50 program were in the greatest agreement. TOXSTAT had the greatest disagreement with the other programs for the probit confidence limits. There was more agreement among the TSK estimates than among the probit estimates. Both EPA programs and the Stephan program require manual data entry with no ability to store the data. If a Windows® operating system environment is desired, either the SAS LC50 or the ToxCalc program is useful. Since SAS LC50 runs in the SAS environment and ToxCalc runs in the Excel™ environment, each is easier to use if one is already familiar with the respective environment.
High-Temperature Accelerant Arson—Revisited
Authors: Keltner NR , Hasegawa HK , White JA
Published: March 2009

In the 1980's, there were a number of unusual arson fires involving very fast fire growth and in some cases premature structural failure. These characteristics posed great risks for fire fighters. The evidence, such as melted steel, indicated that a high temperature accelerant was involved. To support their investigation into these fires, the Seattle Fire Department organized a large scale demonstration. An accelerant with characteristics similar to rocket propellant was used to initiate a fire in a 1900 m2 room in a single story building. The accelerant produced peak heat fluxes of 250–300 kW/m2 in approximately five seconds. Approximately two minutes after ignition of the accelerant, there was an apparent backdraft event and then flashover occurred. The building was heavily involved within four minutes.

From this demonstration, the Seattle Fire Department developed and distributed information to help other fire departments recognize certain characteristics of this type of arson and modify their procedures to protect their personnel.
Large Compartment Fire Tests on a Full-Scale Eight Storey Building
Authors: Lennon T
Published: March 2009

A series of fire tests have been undertaken on a purpose built eight storey, three bay by five bay steel frame building with composite floors and overall dimensions 33.5m by 21m by 45m. The building has been constructed at the BRE's Large Building Test Facility at Cardington, near Bedford, England. As part of the overall fire programme, BRE have carried out fire tests on a compartment (9m x 6m) representative of a corner office and a large compartment (21m x 18m) representative of a large open plan office. The objectives of the programme are to examine the behaviour of multi-storey steel-framed buildings subject to real fires and to use the data from the tests to validate computer models for structural analysis at elevated temperatures. The work will provide substantial benefits and produce high quality data which will inform decisions on the degree of fire protection required for steel framed buildings, which could significantly reduce costs while maintaining existing levels of safety.
Reconstruction of Very Large-Scale Fires
Authors: Saito K
Published: March 2009

This paper describes scale modeling of very large scale fires as a practically useful means to investigate thoroughly their mechanisms in laboratory. A good example of very large scale fires is “fire whirls”. If they are generated in urban and wildland fires, they can be dangerous for the fire fighters nearby the fire whirls and will cause extensive damage in environments. For over 20 years we have collected information and conducted experimental studies of fire whirls in mass fires using scale models. These studies indicated that a large mass fire often broke out when a large earthquake hit a city of dense population. The mass fire-related casualties and destruction were far more serious than those caused by destruction of buildings and houses by the earthquake itself. A good example is the 1938 Tokyo earthquake which caused mass fires and fire whirls claiming 38,000 deaths.
Experimental Measurement of a Shipboard Fire Environment with Simulated Radioactive Materials Packages
Authors: Koski JA , Wix SD , Beene DE
Published: March 2009

Results from a series of eight test fires ranging in size from 2.2 to 18.8 MW conducted aboard the Coast Guard fire test ship Mayo Lykes at Mobile, Alabama are presented and discussed. Tests aboard the break-bulk type cargo ship consisted of heptane spray fires simulating engine room and galley fires (across bulkhead assault), wood crib fires simulating cargo hold fires (direct assault), and pool fires staged for comparison to land-based regulatory fire results. Primary instrumentation for the tests consisted of two pipe calorimeters that simulated a typical package shape for radioactive materials packages. The calorimeters were both located adjacent to the fires and on the opposite side of the cargo hold bulkhead nearest the fire. The calorimeters were constructed from 1.5 m length sections of nominal 2 foot diameter schedule 60 steel pipe. Type K thermocouples were attached at 12 locations on the circumference and ends of the calorimeter. Fire heat fluxes to the calorimeter surfaces were estimated with the use of the Sandia SODDIT inverse heat conduction code. Experimental results from all types of tests are discussed, and some comparisons are made between the environments found on the ship and those found in land-based pool fire tests.
A Food Web Model of Mercury Transfer from Stream Sediment to Predators of Fish for Ecological Risk Based Clean-Up Goals
Authors: Burns TP , Hadden CT , Cornaby BW , Mitz SV
Published: March 2009

A linear steady state model of the food web linking sediment to piscivorous predators was used to derive ecological risk based clean-up concentrations for mercury in sediment of East Fork Poplar Creek (EFPC), Oak Ridge, TN. The model partitions aquatic invertebrates into two classes based on the primary source of exposure to mercury in sediment, and the prey-fish community into three classes based on differences in their diets and feeding habits. Biotransfer factors for the links between sediment and sediment-dwelling invertebrates, water and aquatic biota and fish, and prey and predators are published values. The model uses site specific data on the fraction of methylmercury in sediment, the relative abundance of prey fish, and the predicted flux of mercury from sediment. Monte Carlo analysis quantifies the uncertainty in the risk to top predators of fish. At 96 mg/kg mercury in sediment, less than 20% of the exposures exceed dietary limits for endpoint receptors. The fraction of methylmercury in sediment, the three biotransfer factors for methylmercury, and diet are sensitive parameters.
Graphical Determination of Metal Bioavailability to Soil Invertebrates Utilizing the Langmuir Sorption Model
Authors: Donkin SG
Published: March 2009

A new method of performing soil toxicity tests with free-living nematodes exposed to several metals and soil types has been adapted to the Langmuir sorption model in an attempt at bridging the gap between physico-chemical and biological data gathered in the complex soil matrix. Pseudo-Langmuir sorption isotherms have been developed using nematode toxic responses (lethality, in this case) in place of measured solvated metal, in order to more accurately model bioavailability. This method allows the graphical determination of Langmuir coefficients describing maximum sorption capacities and sorption affinities of various metal-soil combinations in the context of real biological responses of indigenous organisms. Results from nematode mortality tests with zinc, cadmium, copper, and lead in four soil types and water were used for isotherm construction. The level of agreement between these results and available literature data on metal sorption behavior in soils suggests that biologically relevant data may be successfully fitted to sorption models such as the Langmuir. This would allow for accurate prediction of soil contaminant concentrations which have minimal effect on indigenous invertebrates.
Indicators of Chemical Stressor Levels Derived from Population Time Series: A Retrospective Modeling Approach
Authors: Hallam TG , Funasaki ET
Published: March 2009

Transient and asymptotic behavior of a physiologically structured, chemically stressed, individually based Daphnia population model developed for assessment purposes is investigated. An analysis employing this model as a foundation is performed to determine indicators for the magnitude of chemical stress. Using summary statistics, such as total population biomass and total population size time-series data, various approaches, including dynamical systems methodology and a technique based on the mean and variance of total population biomass, were used to generate indicators from these data that could specify the concentration of chemical producing the observed Daphnia population dynamics. In this model setting, only the last approach exhibits promise for identifying indicators of chemical stress.
Environmental Monitoring at Two Department of Energy Sites
Authors: Gray RH
Published: March 2009

The U.S. Department of Energy's Hanford Site was established in southeastern Washington to produce plutonium during World War II. The Pantex Plant in the Texas Panhandle was originally used for loading conventional ammunition shells and bombs, but was rehabilitated and enhanced in the 1950s to assemble nuclear weapons. Environmental monitoring has been ongoing at both locations for several decades. Monitoring objectives are to detect and assess potential impacts of facility operations on air, surface and ground waters, foodstuffs, fish, wildlife, soils, and vegetation. Measured concentrations of airborne radionuclides around the perimeters of both sites are currently below applicable guidelines. Concentrations of radionuclides and nonradiological water quality in the Columbia River at Hanford, and radiological and nonradiological water quality in the Ogallala Aquifer beneath the Pantex Plant are in compliance with applicable standards. Foodstuffs irrigated with river water downstream from the Hanford Site show levels of radionuclides that are similar to those found in foodstuffs from control areas. The low levels of 137Cs and 90Sr in some onsite Hanford wildlife samples and concentrations of radionuclides in soils and vegetation from onsite and offsite at both locations are typical of those attributable to naturally occurring radioactivity and to worldwide fallout. The calculated dose potentially received by a maximally exposed individual (i.e., based on hypothetical, worst-case assumptions for all routes of exposure) at both sites in 1994 was ≤0.05 mrem. Ironically, by virtue of its size (1,450 km2 [560 mi2]), restricted public access, and conservative use of undeveloped land, the Hanford Site has provided a sanctuary for plant and animal populations that have been eliminated from, or greatly reduced on, surrounding agricultural and range lands. Ongoing studies will determine if this is also true at Pantex Plant.
Ecological Risk Assessments of Priority Substances in Canada: Identification and Resolution of Difficult Issues
Authors: Moore DRJ , Breton RL , Doyle P , Elliott BJ , Taylor K , Windle WM
Published: March 2009

Environment Canada has revised its guidance manual for ecological risk assessments of priority substances under the Canadian Environmental Protection Act. This paper briefly summarizes the guidance provided on: problem formulation; data collection and generation; analysis of entry, exposure and effects; and risk characterization. The purpose of this paper is to discuss some of the difficult issues common to all programs conducting ecological risk assessments of substances, and to describe the approaches we have taken. Example issues include: (1) how should low toxic effects be determined, (2) how should risks be quantified, and (3) how can the ecological consequences of exposures to substances be determined? Finally, comments are provided on the process followed during the preparation of the revised manual. These comments are provided because we believe that the open and transparent process followed was beneficial to the identification and resolution of these and other difficult issues.
Methods for Assessing Watershed-Scale Aquatic Risks for Multiple Stressors
Authors: Parkhurst BR , Warren-Hicks WJ , Creager CS
Published: March 2009

We demonstrate how watershed-scale aquatic ecological risk assessments (ERAs) for multiple Stressors are conducted. Most ERAs focus on toxic chemicals, however, many Stressors may affect aquatic ecosystems within watersheds. Other watershed-scale aquatic Stressors include physical and hydrologic Stressors, and physical habitat degradation. We demonstrate a method for quantifying the risks of these other Stressors and comparing the resultant non-toxic chemical risks with toxic chemical risks, using habitat models to estimate the effects of non-toxic chemicals on habitat quality. This information is then compared to the risks from chemical toxicity, and the results used to compare the relative risks of chemical toxicity with the risks of other types of Stressors, to identify the most limiting factors. With this information, the most beneficial types of ecological restoration can be identified and resources allocated to provide the greatest ecological benefit to the watershed.
Screening Level Model for Vadose Zone and Ground Water Transport Evaluation
Authors: Rzepecki PA , Edlund MD
Published: March 2009

This paper hypothesizes that equations used by numerous screening models to calculate ground water mixing zone depth are conceptually incorrect. The models incorrectly omit contaminated infiltration volumes in calculating the resulting aquifer contaminant mixing and concentrations. As a consequence dilution factor, DF, and site cleanup criteria are also calculated incorrectly. The paper proposes a conservative, yet more reliable, method of estimating dilution factor which takes into account mixing by a receptor point pumping well and downward contaminant displacement due to natural infiltration. Aquifer contaminant concentrations are calculated at the down-gradient edge of the vadose zone source's planar projection on the water table. Processes addressed include advection, degradation, sorption, and volatilization. Using a spreadsheet setup, model equations allow the user to quickly evaluate multiple modeling scenarios with varying source geometry, vadose zone thickness, and soil heterogeneity.
Ecological Risk Assessment Procedures for U.S. Army Sites
Authors: Wentsel RS , Simini M , Checkai RT , Ludwig D , La Point TW
Published: March 2009

This paper discusses U.S. Army guidance procedures for ecological risk assessments (ERA) for risk assessors under contract to the U.S. Army. Using this approach provides the Army with cost-effective, tiered procedures with which to direct and coordinate the scientific and technical efforts of contractors involved in ERA. Employing a common framework across sites can assure the Army that requirements of state and federal regulators are satisfied. The process described in this report follows the EPA “Framework” paradigm put forward in 1992. This document is a technical “road map”, with examples and discussion of the thought process to lead environmental scientists through this effort. A tiered or phased approach has been put forward as a rational procedure by several scientists. The purpose of a tiered approach is to do the necessary and sufficient amount of work to characterize the risk to an ecological system with an acceptable degree of uncertainty. The assessment should proceed if risk is possible, but complete characterization of risk cannot be determined due to significant data gaps. The assessment should not proceed if no significant risk is apparent, or if the risk is so great that action (e.g., remediation, containment, etc.) is immediately warranted.
Predicting Dermal Absorption from Contact with Chemically Contaminated Soils
Authors: Bunge AL , Parks JM
Published: March 2009

Dermal absorption from contaminated soils is poorly understood and more experimental study is needed. To guide selection of experimental variables for testing and to facilitate interpretation of resulting data, we have developed mathematical models describing dermal absorption of organic chemicals (1.59 ≤ log10Kow ≤ 5.53 and MW≤ 700) from contaminated soils (with about 0.2% or more organic carbon and with clay fractions which are less than 60 times the weight fraction of organic carbon). Assumptions about the kinetics of soil desorption relative to dermal absorption must be included in these models, although little quantitative information is presently available. Consequently, the models presented here represent two extreme situations in which either the dermal barrier, or the soil controls the rate of dermal absorption. For estimating the relative effect of changing exposure conditions (e.g., changes in soil loading, contamination levels, chemical, etc.), the predictions from both models are generally consistent with experimental results. However, the models assuming fast soil release kinetics predict more absorption than was observed experimentally for lindane and 2,4-D. This suggests that soil release kinetics may limit the amount of dermal absorption in at least some situations.
Indirect Exposure Screening Model for Evaluating Contaminant Intake from Air Emissions Via Ingestion of Milk and Beef: Risk-Based Air Concentrations
Authors: Chew CM , Lorenzana RM , Garry M
Published: March 2009

A conceptual model has been developed to estimate screening level, risk-based contaminant air concentrations with respect to human health risks from indirect exposures to air emissions. The model can evaluate risks from products of incomplete combustion, principal organic hazardous constituents associated with hazardous waste incinerator emissions and other air emittants. Derivation of screening levels is facilitated with a computer spreadsheet requiring six input values. To avoid complex air modeling, estimates are used for some parameters, such as particle deposition rate. The risk-based air concentrations can be used in the early stages of a risk investigation (prior to the trial burn at some incinerator sites) for screening purposes. These risk-based air concentrations can be compared to air concentrations extrapolated from trial burn or other relevant site historical data to determine whether or not a significant risk due to indirect exposures may be present. If screening comparisons reveal the possibility of significant risks, a more extensive risk assessment analysis can be performed and risk-drivers can be identified early in the process. Conversely, if significant risk is clearly not present for contaminants of concern, the analysis can be concluded cost-effectively with the screening process.
Science, Science Policy, and Risk-Based Management
Authors: Midgley LP
Published: March 2009

Recent national awareness of the economic infeasibility of remediating hazardous waste sites to background levels has sparked increased interest in the role of science policy in the environmental risk assessment and risk management process. As individual states develop guidelines for addressing environmental risks at hazardous waste sites, the role of science policy decisions and uncertainty must be carefully evaluated to achieve long-term environmental goals and solutions that are economically feasible and optimally beneficial to all stakeholders. Amendment to Oregon Revised Statute 465.315 (1995; Oregon House Bill 3352) establishes policy and Utah Cleanup Action and Risk-Based Closure Standards (R315-101) sets requirements for risk-based cleanup and closure at sites where remediation or removal of hazardous constituents to background levels will not be achieved. This paper discusses the difficulties in effectively integrating potential current and future impacts on human health and the environment, technical feasibility, economic considerations, and political realities into environmental policy and standards, using these references as models.

Substantive revision of policy and processes requires the managing of science policy to prevent layering of biased assumptions within the risk assessment and risk management processes. The challenges facing process change are many, and include both technically complex and politically sensitive issues. Techniques such as probabilistic risk assessment and decision analysis can be used to quantitate risks and tradeoffs, and introduce a degree of reasonableness and objectivity to the risk assessment and management processes. However, the achievement of meaningful change will also require confronting subjective emotional issues and the development of total systems which will ultimately produce the desired results. This paper considers the role of both objective and subjective criteria in the risk-based closure and management processes and makes suggestions for improving the system by which these sites may be reclaimed.
Performance and Reliability of Intermedia Transfer Models Used in Human Exposure Assessment
Authors: Sheldon AB , Dawson HE , Siegrist RL
Published: March 2009

This paper explores the reliability of intermedia transfer models as a function of both performance (i.e., validity) and specific decision objectives. The performance of selected models is gaged by measuring the error associated with practical model applications. Published volatile organic contaminant leaching and volatilization data are compared with deterministic and stochastic modeling results. The observed intermedia transfer modeling error ranges from 6 to 894%. A hypothetical residential exposure scenario is developed for inhalation of benzene vapors volatilized from soil. Experimentally determined and modeled vapor flux rates are translated into time-averaged air concentrations using a simple box model for air mixing. Health risk estimates based on experimental data are compared with the model-based estimates. Contributions to the overall uncertainty in predicted risk from exposure parameter uncertainty is compared with contributions from volatilization model parameter uncertainty. Modeling parameter uncertainty contribution is found to be dominated by the parameter uncertainty contributed from the exposure evaluation. Implications of error and uncertainty for intermedia transfer model usability in human exposure assessment are explored by considering 1) the sensitivity of predicted health risk values to model performance and 2) the consequences of making an incorrect decision.
Macrophage Aggregates: Biomarker for Immune Function in Fishes?
Authors: Blazer VS , Fournie JW , Weeks-Perkins BA
Published: March 2009

Macrophage aggregates (MAs) are believed to be functional equivalents of germinal centers, active in storage of exogenous and endogenous waste products, the immune response, and iron storage and recycling. Numerous studies have shown an increase in their number, size or hemosiderin content in fish collected at contaminated sites. For this reason, MAs have been suggested as potentially sensitive biomarkers of contaminant exposure. Although they are structures observed histologically, it has also been suggested they may be immunotoxicologic biomarkers. To determine possible relationships between MA formation and macrophage function, we examined data from two field studies and one laboratory study. We found a significant correlation between a decreased chemotaxic response of macrophages and the formation of more numerous, smaller MAs in mummichog from a contaminated site. In laboratory-exposures to arsenic, macrophage function appeared to be a more sensitive indicator at the lower levels of dietary arsenic. However, MA appeared to provide a more dose-dependent and comprehensive indicator of toxicity.
Development of Short-Term, Whole-Embryo Assays to Evaluate Detrimental Effects on Amphibian Limb Development and Metamorphosis Using Xenopus Laevis
Authors: Fort DJ , Stover EL
Published: March 2009

Short-term static-renewal studies were performed on Xenopus embryos from day 5 (Stage 46) to day 26 (Stage 54) [21-d test] with copper and acetyl hydrazide to evaluate effects on limb development. Studies with pentachlorophenol, nonylphenol, methimazole (anti-triiodothyronine [T3]), and tamoxifen (anti-estradiol) were also performed from day 50 (Stage 60) to day 64 (Stage 66) [14-d test] to evaluate effects on tail resorption. Both copper and acetyl hydrazide caused abnormal development of the hind limbs at concentrations of ⩾0.5 mg/L and ⩾25.0 mg/L, respectively. Malformation of the hind limbs were primarily characterized as reduction deficiencies, but acetyl hydrazide also caused flexure defects. Pentachlorophenol and methimazole decreased the rate of tail resorption significantly in metamorphs, whereas nonylphenol increased the rate of tail resorption. Tamoxifen had no effect on the rate of tail resorption. These results suggested that alteration in the rate of tail resorption during metamorphosis in Xenopus is at least partially under the control of T3 and/or T3-like hormones. The stimulatory effects observed with nonylphenol did not appear to be associated with estrogenic activity since tamoxifen did not alter the rate of tail resorption.
Chick Embryo Limb Bud Cell Culture for Screening Environmental Contaminants
Authors: Smith MA , Kanti A
Published: March 2009

Few non-mammalian systems have been used as models for assessing the developmental toxicity of environmental contaminants although the U. S. Environmental Protection Agency recognizes mammalian in vitro systems as appropriate developmental toxicity screens. The chick embryo micromass cell culture system was tested for its predictability to screen developmental toxicants to the skeletal system. Four toxicants with known toxicities in the rodent limb bud cell culture system (arsenate, aspirin, caffeine and methylmercury) were chosen for testing in the chick culture system. Cartilage-specific products, proteoglycans, were used to determine differentiation of the cells in culture by staining with Alcian Green then measured using a spectrophotometric method. Proliferation was determined by staining with Crystal Violet. Dose and temporal response experiments were conducted to determine the most sensitive dose and time of exposure to cells in culture. Overall, the micromass cultures of the chick limb buds responded in a manner similar to those seen in the rodent culture.
An Overview of Metals Permitting Alternatives the Importance of Clean Chemistry Techniques for Trace Metal Sampling of Domestic Wastewater and Paper Mill Treated Effluents and Receiving Waters
Authors: Fergen RE , Cooke JP , Boothe P , Bloetscher F
Published: March 2009

Recent years have shown a trend by regulatory agencies towards increased scrutiny of metals in effluent discharges. As a result, stricter enforcement and lower water quality criteria for metals have become more commonplace. Additionally, EPA policy,adopted in May of 1995, promotes the use of dissolved metals to set and measure compliance with water quality standards and presents alternatives to metals permitting.Implementation of such criterion leaves no room for sampling and analysis error, thus putting a premium on obtaining accurate, low concentration trace metal data. At stake are potential noncompliance fines, unnecessary treatment plant modifications, hampering the industrial development of an area, loss of discharge permits, and exposure to increasingly common third-party lawsuits. The scientific and regulatory communities are now in general agreement that historical background receiving water metal concentrations are substantially overestimated (U.S. EPA 1992, Windom et al. 1991). It is therefore reasonable to assume that the same contamination has and is occurring with conventional sampling and analytical methods for effluents. Historically the total recoverable form of the metal was used for evaluation of environmental impact. Recently the EPA (U.S. EPA 1995, U.S. EPA 1994) has recommended the only way to obtain such accurate metal data at low concentrations is through the implementation of clean chemistry techniques. These techniques have been developed in the Oceanographic Community over the past twenty years out of the necessity to minimize contamination and analyze ambient trace metal concentrations which are very low (Bruland et al. 1979, Patterson and Settle 1976, Shiller and Boyle 1985 and 1987). Case studies involving a paper mill effluent copper study, an estuarine receiving water zinc study, and a Virginia municipal wastewater facility are examples of the application and importance of such techniques for the domestic and industrial community. Data are not only defensible to regulators, but provide a more accurate view of background and effluent concentrations. These results improve the integrity of the database and typically resolve the majority of concerns. However, if the metal concentrations are above levels of concern, various permitting alternatives such as the chemical translator approach, water effects ratios, recalculation of mixing zones,seasonally tiered permits or variances could be pursued. These alternatives focus on the toxic forms of the metals. This approach accommodates improved information and data to protect the environment, without diverting significant funds from other needs.
Inhibition of Photosynthesis as an Endpoint for the Photoinduced Toxicity of Intact and Photomodified PAHs
Authors: Huang X-D , Babu TS , Marwood CA , Gensemer RW , Solomon KR , Greenberg BM
Published: March 2009

Light, especially UV radiation, greatly elevates the toxicity of PAHs to plants. We have previously shown that chlorosis is an excellent indicator of PAH toxicity. Usually when chlorophyll (Chl) content is diminished, photosynthesis is also inhibited. Therefore, we tested if photosynthesis was indeed inhibited by PAHs in the presence of Simulated Solar Radiation. A Commonly used measure of in vivo photosynthetic activity in plants is chlorophyll a (Chl a) fluorescence, an assay of electron transport in photosystem II (PSII). This assay can be performed in situ on intact plants within 24 h of application of the chemical. In this study, two methods of collecting Chl a fluorescence data are described. Fluorescence induction was used to measure maximal PS II efficiency and photosynthesis downstream from PS II, with the finding that both were predictive of growth inhibition. Pulse amplitude modulated (PAM) fluorometry which measures steady state PS II efficiency was also used. This technique also detected negative impacts of photomodified anthracene on the plants.
A Field Screening Method Using Earthworms (Eisenia Foetida Andrei) to Evaluate Contaminated Soils
Authors: Wilborn DC , Bollman MA , Gillett CS , Ott SL , Linder GL
Published: March 2009

An on-site biological assessment for soil toxicity was performed using a lumbricid earthworm, Eisenia foetida andrei(Bouche), at the Milltown Reservoir Superfund Site on the Clark Fork River near Missoula, MT. The assessment provided an opportunity to evaluate test containers and methodologies. Sixty-four field test stations, each consisting of three test containers of site soil, a control container of artificial soil, and a container to house soil moisture and temperature recording devices, were used. Laboratory tests were conducted on soil samples from selected field stations. The test containers were constructed from sections of polyvinyl chloride pipe and were found to be suitable in preventing escape of test organisms and damage by animals. The site soils had levels of arsenic, lead, cadmium, copper, and zinc higher than those in surrounding watersheds. Combined mortality for exposure to the site soil was similar in both the laboratory and field tests (1 to 3%). Combined sublethal responses to the site soil were also similar in both laboratory and field tests (3 to 4%). Artificial soil controls in both field and laboratory tests resulted in combined mortality rates of 1% or less. The methodologies employed proved successful in maintaining an adequate soil moisture level and allowed for measurement of soil temperature.