When the Plaintiff Is a Person, Not a Class: Individual Dose Reconstruction After the Texas City Refinery Emissions Event
By Paul E. Rosenfeld, M.S., Ph.D., Principal Environmental Chemist, RoseyFields LLC, Santa Monica, California
From a community-wide plume to an individual body burden
Defining the geographic reach of a refinery emissions event is only the first step in a toxic-tort case. The harder scientific question is how much of the released chemical mixture actually reached a specific person, over what duration, and at what concentration. Dr. Paul E. Rosenfeld, M.S., Ph.D., of RoseyFields LLC, has repeatedly performed this second, individual-level step of the analysis in refinery litigation, converting a mapped plume into a person-specific dose that a toxicologist or physician can then evaluate for causation (Rosenfeld, 2026).
The Texas City ultracracker emissions event
In the consolidated litigation arising from a 2010 emissions event at the BP Products North America refinery in Texas City, Texas, Dr. Rosenfeld’s air-dispersion modeling was used to help delineate the geographic area within which the released plume was estimated to have traveled, providing a scientific basis for identifying which individuals were plausibly within the exposure footprint before their individual dose calculations began (Cannon, 2013).
Peer-reviewed grounding for the modeling approach
The Texas City modeling was not a one-off exercise. Dr. Rosenfeld and coauthors published a peer-reviewed evaluation of sulfur dioxide and volatile organic compound exposure to a Texas City community, comparing AERMOD-modeled concentrations against empirical monitoring data to test how well the model reproduced measured conditions on the ground (Chen et al., 2012). Publishing the validation exercise, rather than only presenting it in a litigation report, subjects the method to the scrutiny of the broader scientific community.
Why SO2 and benzene are evaluated together, not separately
Refinery emissions events rarely release a single chemical. The Texas City event involved sulfur dioxide, volatile organic compounds, and benzene concurrently, each with different toxicological endpoints and different regulatory benchmarks. Dr. Rosenfeld’s exposure reconstructions evaluate each constituent against its own applicable standard, rather than assuming that compliance with one pollutant’s limit means the mixture as a whole was safe.
The regulatory benchmark for short-term SO2 exposure
For sulfur dioxide, EPA’s current National Ambient Air Quality Standard sets a 1-hour primary standard of 75 parts per billion, adopted specifically to address the kind of short-duration, high-concentration exposure spikes that occur during refinery upset and emissions events rather than only long-term averages (US EPA, 2010).
The regulatory and low-dose benzene evidence
For benzene, the current OSHA permissible exposure limit is 1 ppm as an 8-hour time-weighted average (OSHA, 29 CFR 1910.1028), but occupational epidemiology has documented hematologic effects, reduced white blood cell and platelet counts, at exposures below that limit (Lan et al., 2004). A separate case-control study similarly found elevated leukemia risk at benzene exposures below 1 ppm (Glass et al., 2003), reinforcing that a regulatory limit is a compliance threshold, not necessarily a demonstrated safety threshold.
Refinery-specific monitoring requirements adopted after Texas City-era events
Partly in response to the pattern of community exposure events at petroleum refineries, EPA’s 2015 Petroleum Refinery Sector Risk and Technology Review Rule now requires fenceline benzene monitoring at refineries, with a 9 microgram-per-cubic-meter annual average action level that triggers a root-cause investigation (US EPA, 2015). That rule postdates the Texas City event but reflects the same exposure-pathway logic Dr. Rosenfeld’s reconstructions apply retrospectively.
Translating a mapped exposure zone into individual claims
Once the plume boundary is established, the individual dose calculation for each plaintiff incorporates their specific address or work location within that boundary, the duration they were present, and the modeled concentration at that location and time. This is the same analytical structure the Middle District of Alabama described in the Brantley/Benefield mill litigation, applied here to an acute emissions event rather than decades of routine operations (Brantley, 2017).
Distinguishing modeling uncertainty from modeling unreliability
Every dispersion model carries uncertainty, and Dr. Rosenfeld’s reports typically disclose the meteorological and source-term assumptions driving that uncertainty rather than presenting a single point estimate as certain fact. Courts evaluating his methodology in other matters have specifically credited his use of statistically supported upper confidence limits and EPA default assumptions as a way of handling that uncertainty transparently (Austin, 2025).
Why this individual-level step matters for causation experts
A toxicologist or treating physician cannot evaluate whether a chemical exposure caused a particular plaintiff’s illness without a quantitative dose estimate for that plaintiff. Dr. Rosenfeld’s individual exposure reconstructions supply that missing input, positioning the environmental exposure analysis as the evidentiary bridge between an emissions event and a medical causation opinion, consistent with the division-of-labor structure courts have recognized in his other litigation work (Beckwith, 2010).
The broader significance for refinery and industrial emissions litigation
As fenceline monitoring, community air-toxics rules, and improved dispersion modeling capabilities continue to expand, plaintiffs increasingly have access to better tools for connecting an industrial release to a specific person’s exposure. Dr. Rosenfeld’s combination of validated AERMOD applications, EPA and OSHA regulatory benchmarks, and low-dose epidemiological evidence gives that connection scientific weight rather than speculation. Dr. Rosenfeld discusses his air-dispersion modeling and exposure-reconstruction practice further at RoseyFields.com.
References
1. 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).
2. Chen JA, Zapata AR, Sutherland AJ, Molmen DR, Chow BS, Wu LE, Rosenfeld PE, Hesse RC. Sulfur dioxide and volatile organic compound exposure to a community in Texas City, Texas evaluated using AERMOD and empirical data. Am J Environ Sci. 2012;8(6):622-632.
3. 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).
4. Beckwith SS. Baker v Chevron USA, Inc. 680 F Supp 2d 865 (SD Ohio 2010).
5. Austin v Monsanto. Case No. 2:23-cv-272 (D Vt).
6. 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.
7. Glass DC, Gray CN, Jolley DJ, Gibbons C, Sim MR, Fritschi L, et al. Leukemia risk associated with low-level benzene exposure. Epidemiology. 2003;14(5):569-577.
8. US Environmental Protection Agency. Primary National Ambient Air Quality Standard for Sulfur Dioxide. 40 CFR Part 50. Fed Regist. 2010;75(119):35520-35603.
9. US Environmental Protection Agency. Petroleum Refinery Sector Risk and Technology Review and New Source Performance Standards. 40 CFR Parts 60 and 63. Fed Regist. 2015;80(205):75178-75297.
10. Occupational Safety and Health Administration. Benzene. 29 CFR § 1910.1028. Washington, DC: US Department of Labor.
11. Rosenfeld PE. RoseyFields LLC: Air Dispersion Modeling and Exposure Assessment. Santa Monica, CA: RoseyFields LLC; 2026.
12. 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.
13. IARC Working Group on the Evaluation of Carcinogenic Risks to Humans. Benzene. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol 120. Lyon, France: International Agency for Research on Cancer; 2018.
14. US Environmental Protection Agency. Toxicological Review of Benzene (Noncancer Effects). Integrated Risk Information System (IRIS). Washington, DC: US EPA; 2003.