HCRA: Research

Our research goals include improving risk analysis methods, developing insights into significant public health and environmental problems, and increasing understanding of risk analyses by policymakers and the general public. We work to better comprehend the causal links among various hazards and human health and environmental risks, and the costs, benefits, and effectiveness of different risk reduction options. Our interests are global: we address local, regional, national, and international problems and collaborate with other researchers world-wide.

This page provides examples of recent and ongoing projects. Clicking on the name of a HCRA faculty or staff member will link to his or her biography; see our publications page for information on past research efforts. For more information about our research, please contact the researchers named for each project.

Characterizing and Prioritizing Risks
Improving Exposure Assessment
Understanding Dose-Response Relationships
Valuing Risk Reductions

Characterizing and Prioritizing Risks

We conduct research to characterize risks from a variety of contaminants, in a wide range of environmental settings. Our results can be used to evaluate possible interventions and to prioritize problems for future research or policy consideration.

• Aviation-related air pollution: Dr. Jonathan Levy is leading a multi-year initiative to characterize risks from aviation-related activities - primarily near airports - and to determine the most important characteristics of these risks.
• Radon: HCRA Director James K. Hammitt is exploring the practical implications of substituting threshold and hormetic exposure-effect models for the conventional linear no-threshold model, focusing on a proposed regulation that might reduce lung cancer mortality by limiting the concentration of radon in drinking water.
• Contamination from pharmaceuticals and personal care products: Dr. James Shine is leading research on potential health and environmental risks from small amounts of pharmaceuticals and personal care products now routinely measured in the environment.
• Congestion pricing, traffic flow, and air pollution risks: Dr. Jonathan Levy is leading a team examining emissions from traffic flows in New York City, in order to evaluate the air quality and health implications of implementing a congestion pricing program.
• Measures of equity: Dr. Jonathan Levy is developing methods to characterize and quantify environmental equity within risk-based benefit calculations.
• Health benefits from reduced mercury emissions at power plants: HCRA Director James K. Hammitt is examining health risks (including fetal neurotoxicity and heart disease) from mercury emissions at US coal-fired power plants.
• Pesticide risks among low income populations: Drs. Jonathan Levy and Thomas Smith are leading a team using environmental monitoring data, the Stochastic Human Exposure and Dose Simulation Model (SHEDS), and physiologically-based pharmacokinetic (PBPK) modeling to explore potential health risks from pesticides used in low income urban settings.
• Precautionary principle in the US and Europe: HCRA Director James K. Hammitt is collaborating with American and European colleagues in a comparative study of the application of the precautionary principle to environmental health and safety regulation in the US and European Union.

Improving Exposure Assessment

We extend the scientific basis for human and ecological exposure assessment, including fate and transport processes and factors that influence variability and uncertainty in human exposure.

• Children's exposure to mining waste: Dr. James Shine is using a nested case-control study at a major Superfund site to examine how environmental and behavioral factors, including diet and activity patterns, explain differences in blood levels of mine waste contaminants in children.
• Population exposure variability: Dr. Jonathan Levy continues a series of investigations utilizing atmospheric dispersion models and the intake fraction concept to evaluate differences in population exposure and public health benefits across mobile sources in various geographic locations, and among source categories (such as power plants), in the US, China and Mexico.
• Acute exposures to particles and gases: Dr. Helen Suh is continuing her series of panel studies characterizing acute exposures to particles and gases for sensitive populations. Results from these studies are used to investigate the impact of exposure error in epidemiological studies, to identify factors that modify exposures, and to examine the potential for confounding in health effect studies.
• Mercury exposures from coastal ecosystems: Dr. James Shine is addressing whether coastal eutrophication and hypoxia play a role in controlling mercury methylation and biomagnification, and thereby affect human exposure to methyl mercury via seafood consumption.
• Exposure to traffic-related air pollution: Dr. Jonathan Levy is leading a team investigating indoor and outdoor concentrations of traffic-related air pollutants in low-income urban neighborhoods in Boston, to better understand source contributions to personal exposure and implications for asthma etiology.
• Exposure and risk variability across individuals: Drs. Thomas J. Smith and David Kim are investigating the use of physiologically-based toxicokinetic (PBTK) models to develop a better understanding of the effects of 1,3-butadiene exposures on human health.

Understanding Dose-Response Relationships

Dose-response relationships often can be the most uncertain component of a risk analysis. We work to better understand and characterize these uncertainties, and to reduce uncertainty as new scientific methods and results become available.

• Particulate matter: HCRA Director Joel Schwartz and Dr. Francine Laden are continuing the Harvard Six Cities Study to explore the shape of the dose-response curve and the potential existence of thresholds, using flexible regression techniques and Bayesian approaches.
• Diesel exhaust particles: Drs. Thomas J. Smith and Francine Laden are using a unique national cohort of trucking company workers to assess the association between diesel exhaust exposure and lung cancer mortality.
• Genetic characteristics and susceptibility to airborne particles: HCRA Director Joel Schwartz is using a cohort study of subjects who have been genotyped to identify naturally occurring variations in susceptibility through multiple pathways, and examining how those genetic variations modify the risk from particles.
• Spatial variability and dose-response associations: HCRA Director Joel Schwartz and Drs. Helen Suh and Francine Laden are using extensive monitoring data to develop spatio-temporal models to describe exposure to traffic-related pollutants, and then using these detailed models to reanalyze epidemiologic data to refine dose-response associations.
• Using experts to assess uncertainty: Dr. John Evans continues his research using expert elicitation methods, including recent work with six European experts in epidemiology and toxicology to develop a probabilistic characterization of the dose-response relationship for mortality associated with fine particulate matter in ambient air.
• Using PBPK modeling to reduce dose-response uncertainties: Dr. David Kim is examining the growing literature from PBPK modeling to explore less uncertain methods to extrapolate from animal toxicological data to humans, and from high to low doses.

Valuing Risk Reductions

Policy decisions often require weighing changes in human health risks, environmental changes, and costs. Determining the value of changes in health risk and environmental changes often is controversial and challenging.

• Integrating human health and ecological risk valuation: HCRA Director James K. Hammitt and Dr. Katherine von Stackelberg are conducting contingent valuation research to link analysis of risk reductions and benefit values for the effects of polychlorinated biphenyls (PCBs) on human health and ecological risks.
• Willingness to pay and health utility measures for adults and children: HCRA Director James K. Hammitt is leading a series of studies that estimate willingness to pay and/or health-related quality of life measures for reductions in the risks of mortality and acute or chronic illness from contaminants in food and the environment.
• Valuing statistical lives: HCRA Director James K. Hammitt is exploring theoretical issues and their practical implications related to differences between valuing identifiable and statistical lives and between applying approaches based on values per life extended versus per life year gained.