Updated Summary of Regional and National Ambient Background Investigations for PAHs and Metals
Stephen Emsbo-Mattingly, NewFields Environmental Forensics Practice, Rockland, MA
William Swanson, CDM, Cambridge, MA
James Henderson, NewFields Atlanta, Atlanta, GA 

Comparison of International Risk-Based Screening Levels
Amy Quintin, AECOM, Westford, MA
Lucy H. Fraiser, AECOM, Austin, TX

Assessment of Oral and Dermal Exposure to Benzene from Contaminated Soils
Mohamed S. Abdel-Rahman, UMDNJ - New Jersey Medical School, Newark, NJ
Rita M. Turkall, UMDNJ - New Jersey Medical School, Newark, NJ                   

Differential Body Burdens of Various Metals and Organic Compounds in Co-Occurring Marine Bivalves: Implications for Ecological and Human Health Risk Assessment
Jerome Cura, The Science Collaborative, Winchester, MA      
Dr. Donna Vorhees, The Science Collaborative, Winchester, MA
James Occhialini, Alpha Analytical, Westborough, MA

Soil Metal Criteria Development Using the Terrestrial Biotic Ligand Model (TBLM) and Species Sensitivity Distributions
Sagar Thakali, Gradient Corporation, Cambridge, MA              
Herbert E. Allen, University of Delaware, Newark, DE
Dominic M. Di Toro, University of Delaware, Newark, DE

A Rapid Particle Toxicity Assay using Tetramitus rostratus Flagellates
Robert L. Jaffe, Environmental Toxicology Laboratory, Long Island City, NY

Updated Summary of Regional and National Ambient Background Investigations for PAHs and Metals

Stephen Emsbo-Mattingly, NewFields Environmental Forensics Practice, 100 Ledgewood Place, Suite 302, Rockland, MA 02370, Tel: 781-681-5040, Email: smattingly@newfields.com
William Swanson, CDM, 50 Hampshire Street, Cambridge, MA 02139, Tel: 617-452-6274, Email: swansonwr@cdm.com
James Henderson, NewFields Atlanta, 1349 West Peachtree Street, Suite 2000, Atlanta, GA  30309, Tel: 404-347-9050, Email: jhenderson@newfields.com

Ambient background generally refers to the presence of anthropogenic contaminants in various environmental media cumulatively generated by point and non-point sources and distributed by global, regional, and local processes.  The understanding of ambient background in soils, in particular historic fill soil/brownfields, has received a great deal of attention since 2000.  Research consortia including USGS, EPRI, Civic Agencies, and affiliated consultants are producing valuable reference data sets for demonstrating the influence of soil type and land use on contaminant analyte concentrations.  This presentation provides 1) an update on regional and national efforts to better quantify ambient background and 2) technical strategies to differentiate ambient background from point sources, such as former MGPs. 

Studies of urban background in Illinois and Massachusetts provide concentration benchmarks for comparison to surface soils based on land use (i.e., rural, suburban, or urban) and soil type (i.e., fill present or absent).  The presence or absence of fill is particularly important in residential, commercial, and industrial areas around MGPs as demonstrated by a comparison of the Illinois (fill absent) and Massachusetts (fill present) datasets.  This presentation will also discuss recent efforts on the part of the USGS to conduct a comprehensive national background study that includes a greatly expanded list of metals, PAHs, hydrocarbons, and other constituents.  Preliminary results from the New England phases of this project will be presented. 

Comparison of International Risk-Based Screening Levels

Amy Quintin, BS, AECOM, 2 Technology Park Drive, Westford, MA 01886-3140, USA, Tel: 978.589.3000, Fax: 978.589.3100, Email: amy.quintin@aecom.com
Lucy H. Fraiser, Ph.D., DABT, AECOM, 901 South MoPac Expwy, Building 3, Suite 120, Austin, TX, 78746-5776, USA, Tel: 512.330.0507, Fax: 512.330.0468, Email: lucy.fraiser@aecom.com

In response to a growing public concern over the potential environmental and human health-related effects associated with impacted sites, many countries have launched national frameworks for remediation of high priority sites.  Some countries have developed Risk-Based Screening Levels (RBSLs) as part of a national framework.  RBSLs are numerical media concentrations used to inform decision making about land contamination. Many countries have yet to develop their own RBSLs.  Those countries often require that the regulated community to use RBSLs developed for other countries and, in some cases, to select and defend the most appropriate RBSLs for use. 

Understanding the underlying assumptions used in developing internationally available RBSLs and their intended purpose is essential to making informed decisions regarding their use to manage contamination and mitigate risk.  This paper evaluates some of the underlying assumptions used by a representative group of countries in developing RBSLs.

This analysis was, by necessity, done at the level of primary assumptions, methods and technical elements. Despite this fact, some general conclusions regarding use of internationally available RBSLs have been drawn in the paper.

Assessment of Oral and Dermal Exposure to Benzene from Contaminated Soils

Mohamed S. Abdel-Rahman, Ph.D., Pharmacology and Physiology Dept., UMDNJ - New Jersey Medical School, 185 South Orange Avenue, Newark, NJ, 07101, Tel: 407-568-5122, Email: abdelrms@umdnj.edu
Rita M. Turkall, Ph.D., Clinical Laboratory Sciences Dept., UMDNJ - School of Health Related Professions, 65 Bergen Street, Newark, NJ, 07107, Tel: 407-568-5122, Email: turkalrm@umdnj.edu

Soil contamination with dangerous, toxic chemicals remains one of the most difficult problems in this era. Health risk assessments often do not consider the amount of chemicals in soil that are absorbed and their disposition (kinetics).  The aim of these studies was to compare the extent to which adsorption to sandy or clay soils affects the kinetics and the manner in which benzene is subsequently handled in orally or dermally exposed rats.  Dermal exposure increased absorption half-lives to 25-, 60- and 44-fold compared to oral exposure to pure, sandy and clay groups, respectively.  The elimination half-lives following dermal treatment were increased about 2-fold in pure and sandy groups compared to oral treatment, while in the clay group the increase was 13-fold.  The AUC of benzene in both soils was increased after oral and decreased after dermal exposure compared to pure treatments.  The urinary recovery of the dermal pure group was 3-fold of the oral pure group at 48 hours.  Tissue distribution after all oral treatments resulted in the highest concentrations of radioactivity in gastric contents > stomach > fat > duodenum > adrenal.  Highest tissue concentrations or radioactivity after dermal treatment were kidney > liver > treated skin for the pure group while that for soil-treated groups were treated skin > kidney > liver.  The results of these studies revealed that the presence of sandy and clay soil produced qualitative and quantitative differences in the disposition of benzene in the body following oral or dermal treatments.  These differences will impact risk assessment of benzene.  

Differential Body Burdens of Various Metals and Organic Compounds in Co-Occurring Marine Bivalves: Implications for Ecological and Human Health Risk Assessment

Dr. Jerome Cura, The Science Collaborative, Winchester, MA, Email: jjcura@gmail.com
Dr. Donna Vorhees, The Science Collaborative, Winchester, MA, Email: djvorhees@comcast.net
James Occhialini, Alpha Analytical, Westborough, MA, Email: jocchialini@alphalab.com

Research over the past ten years has demonstrated that bioaccumulation of chemicals depends variously on the chemical properties, the species of organism, temporal differences, environmental conditions, and the exposure history of an organism (Luoma and Rainbow, 2005).  There is ample evidence that under field and laboratory conditions, contaminant concentrations in tissue are often species-specific.  For example, investigators have observed species differences in bioaccumulation of: 

• Zinc (summarized in Luoma and Rainbow, 2005) between two filter feeding co-located epibenthic organisms (mussels and barnacles);  
• PCBs between a deposit feeding and a filter feeding bivalve in laboratory uptake experiments (Burgess and McKinney, 1998);
• Various metals and PCBs between mussels and oysters observed in long term regional monitoring data (San Francisco Estuary Institute, 1997);
• Cadmium and copper among grass shrimp, mussels, and quahogs in controlled muti-element laboratory exposures (Rule and Alden, 1996);
• PAHs among various benthic species (as reviewed in Rust et al., 2004). 

These authors comment upon the implications of differential uptake and accumulation when selecting organisms for toxicity testing, bioaccumulation testing, or monitoring. 

These differences pose an uncertainty of generally unknown magnitude in ecological and human health risk assessments which often depend upon a small number of representative species.   Risk assessors commonly select representative species to represent various trophic levels or vulnerabilities (ecological risk assessors) or ingested food types (human health risk assessors) with uncertain knowledge regarding the range of differences in bioaccumulation that may occur even among species of the same feeding type or taxonomic family.  This work measures the range of tissue concentrations for various metals and organic chemicals among co-located bivalves that are both prey for local animal species and a regular food source for recreational shell fishers.  We discuss the implications for selecting representative species in ecological risk assessment and selection of recreationally caught species in human health risk assessment. 

Burgess and McKinney, 1999, Environ. Poll. V 104 Issue 3. 
Luoma and Robinson, 2005, EST, v 39 no 7. 
Rule and Alden, 1996.  Environmental Toxicology and Chemistry, Vol. 15, No. 4
Rust et al., 2004, Environmental Toxicology and Chemistry, Vol. 23, No. 11
San Francisco Estuary Institute, Regional Monitoring Annual Report, 1997
http://www.sfei.org/rmp/1997/index.html 

Soil Metal Criteria Development Using the Terrestrial Biotic Ligand Model (TBLM) and Species Sensitivity Distributions

Sagar Thakali, Gradient Corporation, 20 University Rd., Cambridge, MA 02138, USA, Tel: 617-395-5000, Fax: 617-395-5001, Email: sthakali@gradientcorp.com
Herbert E. Allen, Center for Study of Metals in the Environment (CSME), Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA, Tel: 302-831-8449, Fax: 302-831-3640, Email: allen@udel.edu
Dominic M. Di Toro, Center for Study of Metals in the Environment (CSME), Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716, USA, Tel: 302-831-4092, Fax: 302-831-3640, Email: dditoro@udel.edu

It is widely accepted that critical metal concentration for a specific ecological receptor in different soils varies by orders of magnitude.  In addition the effects of soil chemistry on species sensitivity distributions (SSDs) are not well understood.  Consequently a suitable framework to develop soil metals criteria that is able to account for the variability in critical metal concentrations for individual receptors and the overall species sensitivity distribution—both affected by soil chemistry—does not exist.  A method to develop soil metals criteria is introduced here based on a recently proposed terrestrial biotic ligand model (TBLM) and soil-specific SSD [i.e., for a given soil pH, soil organic matter (SOM) content, and dissolved calcium (Ca) and magnesium (Mg) concentrations in soil solutions].  The TBLM was used to determine soil-specific critical copper (Cu) and nickel (Ni) concentrations (EC₅₀) for six biological endpoints: barley root elongation, tomato shoot yield, springtail juvenile production, red worm cocoon production, glucose induced respiration, and nitrification rate—representing terrestrial plants, invertebrates, and microbes.  A soil-specific SSD was then determined based on the six EC₅₀ values.  The SSD-based HC₅₀ (soil metal concentration protective of 50% of species) and HC₅ (soil metal concentration protective of 95% of species) for Cu and Ni are presented as function of soil pH and dissolved Ca and Mg concentrations in soil solutions.  The HC₅ are also compared to previously suggested soil Cu and Ni criteria.

A Rapid Particle Toxicity Assay using Tetramitus rostratus Flagellates

Robert L. Jaffe, Environmental Toxicology Laboratory, 45-10 Court Square, Long Island City, NY 11101, U.S.A., Tel: 718-392-0185, Fax: 718-392-8654, Email: rljaffe@verizon.net 

Tetramitus flagellates have been grown in the laboratory as stable populations for the last 25 years. Flagellate growth inhibition is the basis for the study of toxic agents found in the environment. Our research has demonstrated the utility of the Tetramitus Growth Inhibition Assay to measure toxic particles in drinking water and ambient water, to define a potential risk factor for increased incidence of  breast cancer on Long Island, to provide a cost-effective and sensitive alternative for compliance monitoring for NPDES permits, for use as an effective Particle Assay for monitoring Stormwater Effluents, and for real-time biomonitoring during environmental triage assessment following terrorist attacks. Using a process of sequential filtration, we were able to demonstrate the toxicity of a respirable subpopulation of dust particles obtained from a Deutsche Bank Dust Sample, provided by the EPA.

The Tetramitus Assay can be performed in less than 30 hours; thus retesting to resolve NPDES compliance issues can be accomplished within 3 days. A Michigan split-sample study on three industrial effluents revealed that the Tetramitus Assay was at least five (5) times more sensitive when compared to the Ceriodaphnia and fat head minnow tests conducted on the same samples.

First flush deposition of toxic particles after the onset of a rain event was also demonstrated in our stormwater monitoring of the Kisco River. The peak in particle toxicity at ~ 6 hours preceded the peak of total sediment deposition at 17 hours. We also present a rapid and simple method for preparation of particle suspensions for use with the Tetramitus Assay. In addition, we demonstrated the extraordinary growth stability of sixteen flagellate clones over 20 cycles of growth. 

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