Epidemiology & Toxicology Expert Witness Services for Asbestos, PFAS, Lead & Cr(VI)

Epidemiology is the study of the distribution and determinants of disease in human populations. It is the branch of science that determines, from the human record itself, whether a chemical or other agent causes a particular disease in people. In environmental and occupational exposure analysis, epidemiology is the evidence that answers the causation question directly: not whether an agent causes disease in a laboratory model, but whether it has been shown to cause that disease in human beings.

Dr. Paul Rosenfeld has expertise in epidemiology and uses epidemiologic evidence as a core component of his exposure and causation analyses. Epidemiologic studies are relied upon to establish that a given agent causes a specified disease in humans, and that conclusion is then integrated with the other elements of the analysis — exposure reconstruction, air dispersion modeling, environmental forensics, toxicology, and risk assessment — to form the overall opinion. Epidemiology establishes what the agent does to human health; the remainder of the analysis establishes the person’s connection to that agent.

Peer-Reviewed Epidemiologic Publications

Dr. Rosenfeld’s use of epidemiology is grounded in his own published, peer-reviewed research, which spans community health-burden analysis, occupational cohort exposures, and contaminated-media health assessment:

• Remy, L. L., Clay, T., Byers, V., & Rosenfeld, P. E. (2019). Hospital, health, and community burden after oil refinery fires, Richmond, California 2007 and 2012. Environmental Health, 18, 48.
• Rosenfeld, P. E., Spaeth, K., Hallman, R., Bressler, R., & Smith, G. (2022). Cancer risk and diesel exhaust exposure among railroad workers. Water, Air, & Soil Pollution, 233, 171.
• Rosenfeld, P. E., Spaeth, K. R., Remy, L. L., Byers, V., Muerth, S. A., Hallman, R. C., Summers-Evans, J., & Barker, S. (2023). Perfluoroalkyl substances exposure in firefighters: Sources and implications. Environmental Research, 220, 115164.
• Rosenfeld, P. E., Spaeth, K. R., McCarthy, S. J., et al. (2024). Camp Lejeune Marine cancer risk assessment for exposure to contaminated drinking water from 1955 to 1987. Water, Air, & Soil Pollution, 235, 124.

Dr. Rosenfeld has also taught epidemiologic practice — with an emphasis on the investigation of disease clusters — to physicians and nurses as an Adjunct Professor and Lecturer at the UCLA School of Public Health.

Selecting and Weighting the Epidemiologic Evidence

The first task is to identify the human studies that are actually informative for the agent and disease in question, and to characterize what each was capable of detecting.

Dr. Rosenfeld distinguishes among study designs by their structural strengths. Prospective cohort studies follow defined populations forward and permit direct estimation of disease incidence; occupational cohorts assembled from employment records are often the most informative human data for industrial agents, because employment history supplies a temporal framework linking exposure to later disease. Case-control studies are efficient for rare outcomes with long latency and are frequently the principal human evidence for low-incidence cancers. Population health and administrative-data analyses — hospital admissions and diagnosis-coded encounters before and after a discrete event — can measure community health burden where no monitoring network captured the exposure. Systematic reviews and authoritative evaluations, including IARC monographs and agency assessments, supply structured, pre-specified weight-of-evidence conclusions on whether an agent causes disease in humans (IARC, 2019; U.S. EPA, 2005).

Each study is assessed on the comparability of its population, outcome ascertainment, latency, follow-up completeness, statistical power, and the adequacy of its comparison group — not on the direction of its result (Checkoway et al., 2004; Rothman et al., 2008). Where a body of literature is assembled, the greatest weight is given to findings that are consistent across independent populations and methods: when studies conducted in different countries, using different designs and different exposure-assessment approaches, agree that an agent is associated with a disease, that consistency is strong evidence that the agent causes the disease rather than that the association arose by chance in a single study.

Establishing Causation and Integrating Epidemiology into the Analysis

The purpose of the epidemiologic evaluation is to establish general causation — that the agent is capable of causing the specified disease in humans. Where the peer-reviewed human literature, together with authoritative evaluations such as the IARC monographs, establishes that an agent causes a particular disease, that determination becomes a fixed foundation of the analysis.

Epidemiology is then integrated with the other elements of Dr. Rosenfeld’s work. Having established from the human evidence that the agent causes the disease, the analysis turns to the individual: characterizing the source, reconstructing the person’s exposure to the agent, and evaluating that exposure in light of the human health record. In this way the epidemiology and the exposure analysis are complementary — the epidemiology supplies the causal link between agent and disease, and the exposure reconstruction supplies the link between the person and the agent. Neither alone is sufficient; together they support a conclusion to a reasonable degree of scientific probability.

Methodologies applied in this practice are evaluated under Daubert and analogous standards.

Where This Applies

Dr. Rosenfeld applies epidemiologic data to distinct questions, each requiring distinct evidence:

• General causation — whether an agent causes a specified disease in humans. This is answered from the human evidence base, supported by the authoritative weight-of-evidence evaluations.
• Acute release and community health burden — population health effects following discrete industrial events, including analysis of hospital and health-service utilization where monitoring data are absent.
• Cluster investigation — evaluation of reported disease clusters, including the comparison of observed to expected disease counts.
• Critical review — evaluation of the methodology and conclusions of epidemiologic analyses offered by others, including identification of unstated assumptions and inferences that exceed what the underlying data support.

The frameworks governing epidemiologic evidence in adjudicative settings are summarized in the Reference Manual on Scientific Evidence (Federal Judicial Center & National Research Council, 2011). Epidemiologic literature is relied upon for what it establishes about disease causation in human populations, and it is integrated with the exposure and toxicological components of the analysis to form the overall opinion.

References