My primary responsibility with the Indoor Environment Department at Lawrence Berkeley National Lab is to assist in the development, evaluation and application of multimedia environmental fate and multi-pathway exposure models. My research cuts across several areas related to the development and evaluation of regulatory environmental models. Specifically, I am working on the development and improvement of mass balance models used to characterize the fate of multimedia pollutants and evaluation of these models in the context of exposure assessment and regulatory decision making. To facilitate the evaluation of complex environmental models, I proposed a framework for evaluation of these models and developed an integrated sensitivity-uncertainty analysis method that is used to classify stochastic model inputs for specific applications. I've worked to improve experimental and analytical methods for quantifying relevant intermedia transfer factors and concentrations of semi-volatile organic pollutants in environmental media. I'm also working on constructing "default" distributions for exposure factors and development of a framework for evaluating the adequacy of probabilistic risk assessments.

After earning a B.S. in Environmental Toxicology (UC Davis, 1992) and a Ph.D. in Agricultural and Environmental Chemistry (UC Davis, 1998) I've continued to be interested in contributing to an understanding of how and/or to what extent plants influence the fate and transport of environmental pollutants. It has long been recognized that vegetation can accumulate pollutants from other environmental compartments. However, the role of vegetation in controlling the environmental fate of pollutants has not been well characterized. As a result, including vegetation in multimedia mass balance models in the context of exposure assessment remains highly uncertain. I have continued an involvement with laboratory investigations that we hope will lead to more robust and reliable plant models for inclusion into multimedia fate and exposure models.

I focused considerable effort over the past year on both the philosophical and the methodological issues related to the validation of complex regulatory environmental model. To get a handle on this important but challenging problem, I participated in workshops, organized sessions and authored presentations on the "Credibility of Regulatory Environmental Models". The lessons that I learned from this effort have gone into the development of an evaluation framework for complex models. I am also working on new sensitivity analysis methods that are designed to evaluate the explanatory power or internal workings of these models in order to better characterize the causality that is built into a given model application. The premise behind this effort is that understanding "why" a model makes a particular prediction can improve our ability to judge the credibility and adequacy of the model for the given task.

The recent release of the Risk Assessment Guidance for Superfund, Volume III (Draft), titled "Process for Conducting Probabilistic Risk Assessment" prompted the need for relevant default distributions and research into methods for evaluating the adequacy of probabilistic risk assessments (PRA). As with any model application, the credibility of the PRA is directly related to the credibility and adequacy of the input distributions used in the analysis. Prior to making a decision about the appropriateness of an exposure factor PDF for a given cohort or scenario, it is necessary to critically evaluate the entire process leading up to and including the use of the distribution in the probabilistic assessment. The range of information (both qualitative and quantitative) that comes out of the distribution development process is of critical importance when judging the adequacy of the distributions. Working with other members of the California Exposure Modeling Research Center we've developed a preliminary scoring methodology that moves toward combining the qualitative and quantitative information that emerges from the distribution development process in order to facilitate evaluation of distributions used in probabilistic risk assessments.

Maddalena, R.L., T.E. McKone and N.Y. Kado (submitted) “Exposure Chamber Measurements of Mass Transfer and Partitioning at the Plant/Air Interface” Environ. Sci. Technol.

Maddalena, R.L., T.E. McKone, D.P.H. Hsieh and S. Geng (2000) “Influential Parameter Classification in Probabilistic Multimedia Models” In Press. Stochastic Environmental Research and Risk Assessment.

Maddalena, R.L. (1998) "Model Directed Investigation and Measurment of the Fate of Polycyclic Aromatic Hydrocarbons Among the Atmosphere and Vegetation" Ph.D. Dissertation, University of California, Davis.

Maddalena, R.L., T.E. McKone and N.Y. Kado (1998) "Simple and Rapid Extraction of Polycyclic Aromatic Hydrocarbons Collected on Polyurethane Foam Adsorbent" Atmospheric Environment, 32 2497-2503

McKone, T.E. and R.L. Maddalena, (1997) “Soil Contamination and Human Exposure: A Comprehensive Assessment of Exposure Analysis Methodology” International Journal of Toxicology, 16 319-337.

Maddalena, R.L., T.E. McKone, D.W. Layton, D.P.H. Hsieh, (1995), “Comparison of Multi-Media Transport and Transformation Models: Regional Fugacity Model vs. CalTOX”, Chemosphere, 30 (5) 869-889.

Reports

Maddalena R.L., T.E. McKone, A. Bodnar and J. Jacobson (1999) “Development and Evaluation of Probability Density Functions for a Set of Human Exposure Factors” Submitted to U.S. Environmental Protection Agency, Office of Emergency and Remedial Response (DE-AC03-76SF00098)

Kado, N.Y., P.A. Kuzmicky., R.L. Maddalena, TL Huang, and R.A. Okamoto, (1998). Draft Final Report “Exposure to Emissions from Alternative Fuel Combustion: Bioassay and Chemical Analyses of the Particle and Semi-Volatile Emissions from Hydrogenated Biodiesel Fuels." Submitted to U.S. Department of Energy.

Kado, N.Y., P.A. Kuzmicky, K.L. Kiefer, R.L. Maddalena, T.L. Huang, and R.A. Okamoto, (1998). A. Draft Final Report "Chemical and Bioassay Analyses of the Particle and Semi-Volatile Emissions from Biodiesel Soy Methyl Ester Fuel." Submitted to U.S. Department of The National Renewable Energy Laboratory and the U.S. Department of Energy.

McKone, T.E., R.L. Maddalena, R. Currie, K. Kiefer, D.P.H. Hsieh, ” Representing Uncertainty in Risk Assessment: Part 4. Ranking Uncertain Parameters.” Submitted to The Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Berkeley CA, December 1995.

Recent Presentations

Maddalena, R.L (2000) “Process Level Sensitivity Analysis for Evaluating Complex Models” Presented at the Society of Environmental Toxicology and Chemistry North American Conference, Nashville TN

Maddalena, R.L, D.H. Bennett, R.G. Hetes and D.L. Murphy (2000) “Evaluation of a Complex Environmental Model: The TRIM.FaTE Example” Presented at the Society of Environmental Toxicology and Chemistry North American Conference, Nashville TN

Maddalena, R.L., T.E. McKone and A. Bodnar (2000) “Evaluation of Probability Density Functions – Case Studies at the Extremes” Society for Risk Analysis, Arlington VA.

Maddalena, R.L. and T.E. McKone (2000) “Relevance versus Reliability in Source-to-Dose Models for Particulate Matter” Presented at the International Society for Exposure Analysis, Monterey, CA

Maddalena. R.L. (1999) “Calibration and Validation in the Real Multimedia World” Society for Risk Analysis Conference, Atlanta, GA

Maddalena, R.L. and T.E. McKone (1998) “Measurement and Modeling Implications of Partitioning, Transfer and Transformation Processes at the Air/Plant Interface” Invited Paper – Annual SETAC Conference, Charlotte, NC

Maddalena, R.L.; T.E., McKone and N.Y. Kado (1998) “A Continuous Stirred Tank Reactor Exposure System for Investigating the Role of Vegetation in the Fate of Semivolatile Air Pollutants” Platform presentation presented at Annual SETAC Conference, Charlotte, NC