Thirty Cases, One Method: What Three Decades of Historical Exposure Reconstruction Actually Look Like
By Paul E. Rosenfeld, M.S., Ph.D., Principal Environmental Chemist, RoseyFields LLC, Santa Monica, California
A single methodology applied across a remarkably wide range of chemicals
Across the litigation and research history described throughout this case study series, Dr. Paul E. Rosenfeld, M.S., Ph.D. of RoseyFields LLC has applied a strikingly consistent underlying methodology, historical source and emissions reconstruction, dispersion or transport modeling, and quantitative dose and risk calculation, to an unusually broad range of contaminants: benzene, diesel exhaust, PCBs and dioxins, PFAS, heavy metals, chlorinated solvents, silica, atrazine, and MTBE, among others.
Air, water, and soil as three interconnected pathways, not three separate practices
The Brantley and Cannon refinery matters, the Custer and Bethpage groundwater and dioxin matters, and the Duarte and Camp Lejeune soil and drinking-water matters illustrate that the same underlying fate-and-transport reasoning, tracking how a chemical moved from its source to a specific person over a specific period, applies across air, water, and soil pathways, even though the specific modeling tools differ, AERMOD for air, groundwater flow and transport modeling for water, spatial statistical analysis for soil.
Regulatory-grade tools as a recurring credibility anchor
In nearly every matter described in this series, the underlying modeling relied on EPA’s own preferred regulatory tools, AERMOD for air dispersion, EPA’s IRIS toxicity values, EPA’s Exposure Factors Handbook default parameters, giving courts and juries a basis for evaluating the methodology against the same standards the responsible federal regulatory agency itself uses, rather than a bespoke litigation-only approach.
Peer-reviewed publication as a check against litigation bias
A recurring pattern across this series is that key methodological elements, attic dust forensics, odor wheel classification, diesel exhaust cancer risk calculation, PFAS firefighter exposure assessment, Camp Lejeune historical drinking-water reconstruction, were developed and published in peer-reviewed scientific literature independent of any specific litigation, subjecting the underlying science to scrutiny beyond what any single case’s adversarial process provides.
Honest accounting of outcomes, including losses and limits
This series has also documented instances where the underlying legal theory did not prevail, Andrews v. Antero’s severance-deed doctrine, or where damages fell well short of what was sought despite a favorable liability finding, Red Hill’s bellwether trial, because an accurate professional record includes unfavorable outcomes and their specific legal reasons, not only favorable verdicts and settlements.
Low-dose epidemiology as the connective tissue between exposure and harm
Across chemical classes, this series has repeatedly returned to foundational, independently conducted epidemiological studies, Lan et al.’s benzene hematotoxicity findings, Garshick’s railroad diesel cohort, the C8 Science Panel’s PFOA findings, Bove et al.’s Camp Lejeune mortality study, illustrating that exposure reconstruction is only scientifically meaningful when paired with dose-response evidence developed independent of any specific defendant or plaintiff.
Why regulatory standards keep moving, and why that matters
Multiple matters in this series, PFAS drinking-water limits, ethylene oxide cancer potency, silica permissible exposure limits, occurred against a backdrop of regulatory standards tightening substantially over time as toxicological understanding improved, meaning historical exposure reconstruction must always specify which regulatory standard applied during the actual exposure period, rather than retroactively applying today’s tighter standard to yesterday’s exposure.
Novel combinations, not novel individual techniques
Few individual techniques described in this series, dispersion modeling, attic dust sampling, odor classification, cohort epidemiology, are themselves novel; the recurring contribution across this body of work has been combining established techniques from separate disciplines, atmospheric science, environmental forensics, industrial hygiene, and regulatory toxicology, into a single, internally consistent exposure reconstruction tailored to each specific contamination scenario.
Why this approach scales from a single plaintiff to a fourteen-thousand-claimant settlement
The same underlying methodology that reconstructs an individual railroad worker’s diesel exposure over a 38-year career also scales to allocate compensation across an estimated 14,000 claimants in the Grain Processing Iowa settlement, demonstrating that rigorous historical exposure reconstruction is equally applicable to single-plaintiff FELA litigation and to mass tort settlement administration.
Why historical exposure reconstruction will remain central to environmental litigation
As industrial facilities continue to close, change hands, or face newly discovered legacy contamination, and as regulatory science continues to identify health effects at exposure levels once considered safe, the demand for scientifically rigorous, historically grounded exposure reconstruction is unlikely to diminish. More on this area of Dr. Rosenfeld’s practice, environmental exposure reconstruction work, is posted at RoseyFields.com.
References
1. Brantley TL, et al. v International Paper Company. Civil Action No. 2:09-230-DCR-TFM, Memorandum Opinion and Order (MD Ala May 24, 2017).
2. Cannon K, Donovan E, Ramirez G, Sassler C, Walton H, et al. v BP Products North America, Inc. Case No. 3:10-cv-00622 (SD Tex).
3. Andrews RL, et al. v Antero Resources Corporation and Hall Drilling, LLC. No. 17-0126, Supreme Court of Appeals of West Virginia (June 10, 2019).
4. Feindt PJ, Jr., et al. v The United States of America. Case No. 1:22-cv-LEK-KJM, US District Court for the District of Hawaii; trial March 29-April 5, 2024.
5. Lan Q, Zhang L, Li G, Vermeulen R, Weinberg RS, Dosemeci M, et al. Hematotoxicity in workers exposed to low levels of benzene. Science. 2004;306(5702):1774-1776.
6. Garshick E, Schenker MB, Munoz A, Segal M, Smith TJ, Woskie SR, Hammond SK, Speizer FE. A retrospective cohort study of lung cancer and diesel exhaust exposure in railroad workers. Am Rev Respir Dis. 1988;137(4):820-825.
7. C8 Science Panel. Probable Link Reports: PFOA and Human Disease. Mid-Ohio Valley, WV/OH: C8 Science Panel; 2011-2012.
8. Bove FJ, Ruckart PZ, Maslia M, Larson TC. Evaluation of mortality among Marines and Navy personnel exposed to contaminated drinking water at USMC Base Camp Lejeune: a retrospective cohort study. Environ Health. 2014;13:10.
9. In re Grain Processing Corporation Litigation (Muscatine County, Iowa nuisance class action, filed 2012); settlement approved 2019.
10. US Environmental Protection Agency. Revisions to the Guideline on Air Quality Models. 40 CFR Part 51, Appendix W. Fed Regist. 2017;82(10):5182-5235.
11. US Environmental Protection Agency. PFAS National Primary Drinking Water Regulation. 40 CFR Parts 141 and 142. Fed Regist. 2024;89(81):32532-32757.
12. Occupational Safety and Health Administration. Occupational Exposure to Respirable Crystalline Silica. 29 CFR § 1910.1053.
13. US Environmental Protection Agency. Exposure Factors Handbook. Washington, DC: US EPA Office of Research and Development.
14. Rosenfeld PE. RoseyFields LLC: Historical Exposure Reconstruction Across Air, Water, and Soil Pathways. Santa Monica, CA: RoseyFields LLC; 2026.