Dioxin Fate-and-Transport Investigation and Human Exposure Assessment Near a Historic Herbicide Manufacturing Facility
Primary Category: Occupational ExposureSecondary Category: Air Dispersion Modeling
Project Overview
RoseyFields conducted a technical environmental forensic investigation involving historical dioxin and furan contamination associated with a former herbicide manufacturing facility in Nitro, West Virginia. The project focused on whether historical manufacturing, waste handling, and waste burning activities at the facility resulted in the airborne release, off-site transport, deposition, and long-term persistence of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in nearby residential and commercial areas. The work integrated historical operations review, fate-and-transport analysis, surface-soil and indoor-dust sampling data, and plaintiff-specific exposure reconstruction to evaluate how dioxin contamination from legacy 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) production could have migrated from the plant and created chronic exposure opportunities for nearby residents and workers. The historical technical materials indicate that Monsanto’s Nitro facility manufactured 2,4,5-T from 1948 through 1969, that dioxin impurities and byproducts were associated with that process, and that waste burning was treated as the dominant atmospheric release pathway for off-site contamination.
The investigation was not limited to a single environmental medium. Instead, it evaluated a multi-media contamination pathway in which dioxins generated during herbicide production and waste handling were released to the atmosphere, transported through the Kanawha Valley, deposited onto surrounding surface soils and structures, and ultimately accumulated in indoor dust and other residential media over time. This framework was particularly important because the available records included both historical dispersion/deposition modeling and later environmental samplingdocumenting dioxin/furan contamination in surface soil and indoor dust at properties in the surrounding community, including areas near 105 Pickens Road. The Graves affidavit also describes decades of presence at Southern Lumber and the Pickens Road property, including residence on-site, daily work at the property, regular entry into the Monsanto plant, and repeated presence in and around the “weed killer” building where 2,4,5-T-related operations occurred.
From a forensic perspective, this project required connecting facility operations, emission mechanisms, environmental measurements, and individual exposure history into a coherent technical assessment. RoseyFields reviewed historical manufacturing information, EPA corrective-action records for the former Solutia/Monsanto Nitro site, engineering analyses of dioxin emissions from waste burning, and multi-media environmental sampling performed in the surrounding community. The resulting case study illustrates RoseyFields’ ability to evaluate legacy industrial contamination, reconstruct historical emissions from incomplete records, interpret dioxin TEQ results in soil and dust, and assess how long-term residential and occupational presence near a contaminated facility can create repeated exposure to persistent organic pollutants decades after the original manufacturing activities occurred.
Chemicals of Concern
The principal chemicals of concern were polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), collectively evaluated as dioxins/furans and often expressed using toxic equivalency (TEQ)relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). The historical source materials identify 2,3,7,8-TCDD and other dioxin congeners as significant impurities and byproducts associated with the manufacture of 2,4,5-T, a chlorophenoxy herbicide historically produced at the Nitro facility from 1948 through 1969. According to the engineering analysis prepared for the Nitro matter, dioxin-containing wastes were disposed and burned at multiple locations over the 22-year production period, and atmospheric releases from that waste burning were treated as the principal source of off-site airborne dioxin contamination.
From a toxicological and environmental perspective, dioxins/furans are particularly significant because they are persistent, bioaccumulative, and strongly sorptive to particles and organic matter, allowing them to persist in soil, indoor dust, sediment, and other environmental media long after the original release. In historical community contamination cases, dioxin exposure is often evaluated through a combination of inhalation of contaminated air during the release period, soil contact and incidental ingestion, and long-term exposure to contaminated indoor dust generated from historical outdoor deposition and indoor accumulation. The Nitro materials reflect exactly that type of framework: atmospheric releases from waste burning were modeled for ambient air concentrations and deposition, while later field programs targeted surface soils and indoor dust to evaluate whether residual contamination remained in the surrounding community.
Methods
The first component of the project was reconstruction of the historical source term for dioxin releases from the former herbicide manufacturing facility. The Auberle report states that Monsanto and its predecessors operated an organic chemical manufacturing facility in Nitro and produced 2,4,5-T from 1948 through 1969, with dioxin generated as an impurity and byproduct of that process. The report further explains that dioxin escaped through multiple waste streams, including wastewater, solid waste disposal, and vents/stacks, but that the greatest atmospheric releases were associated with the burning of dioxin-containing waste materials such as packaging waste, off-specification product, and other solid wastes. Using plant records, employee recollections, and retrospective studies, the report estimated that approximately 2,384 pounds of dioxin were released during the 22-year production period, with a substantial portion associated with waste disposal and combustion.
The source reconstruction also evaluated where and how waste burning occurred. According to the engineering analysis, dioxin-bearing wastes were burned at multiple off-site and on-site locations over time, including the Old Nitro Landfill, Manila Creek, Heizer Creek, a tepee burner, and the former World War I building. A conservative emissions estimate assumed that 50% of the dioxin in waste sent to burning escaped to the atmosphere, resulting in approximately 954 pounds of dioxin emitted to air during the 1948–1969 period. This type of historical source reconstruction is central to environmental forensic work because direct air monitoring data almost never exist for legacy releases; instead, the analyst must reconstruct emissions using historical production records, waste-disposal practices, engineering assumptions, and plant-history evidence.
Once the source term was reconstructed, the project evaluated how those dioxin emissions would have moved through the surrounding environment. The Auberle analysis used AERMOD to model near-field dioxin impacts from historical waste burning and to estimate both ambient air concentrations and wet/dry deposition across the Nitro area. The report states that annual average ambient concentrations and deposition were calculated for each year from 1948 through 1969, and that multi-year averages were also developed for lower- and higher-exposure periods. Although the release period predated modern meteorological datasets, the modeling relied on five years of later Charleston, West Virginia meteorological data processed through AERMET, together with upper-air data from Wilmington, Ohio, to generate an AERMOD-compatible dataset. The report also indicates that AERMAP and digitized terrain data were used to incorporate valley terrain effects and derive receptor elevations.
The deposition component of the modeling was particularly important because dioxin exposure in the community was not conceptualized as a transient air-only event. Instead, the historical emissions were expected to deposit onto soil, structures, and outdoor surfaces, creating long-term reservoirs of contamination that could later contribute to residential and occupational exposure through soil contact, tracking, and indoor dust accumulation. The Auberle report states that AERMOD’s deposition algorithms were used to estimate total dioxin deposition for the 1948–1969 period and that both wet and dry deposition were evaluated using particle-size and density assumptions. This modeling framework is highly relevant in legacy dioxin cases because it provides a technical bridge between historical emissions and present-day environmental measurements, allowing analysts to assess whether observed contamination patterns in soil and dust are consistent with modeled deposition from the historical facility.
The project also relied on environmental sampling performed in the Nitro community to evaluate whether the modeled release/deposition pathway was supported by measured contamination. The 3TM reports describe a multi-phase field program involving surface-soil sampling at dozens of locations in Nitro and surrounding areas. According to the summary report, releases of dioxins/furans from a major source such as the Monsanto plant could affect multiple media, but surface soil was used as a practical means of evaluating the nature and extent of community contamination because airborne dioxins and dioxin-laden dust typically deposit and accumulate in near-surface soils. 3TM reported that its surface-soil sampling indicated widespread contamination in an area extending southward approximately 3.75 milesfrom the former plant and laterally approximately two miles, with the report noting that untested areas may also have been contaminated.
The Phase III field report and the property-specific testing results also show that 105 Pickens Road / lot next to 105 Pickens was one of the sampled locations. The excerpted testing results for Joel and Sandy Graves show surface-soil dioxin/furan measurements at or adjacent to 105 Pickens and report TEQ values in the hundreds of ppt range for both Phase I and Phase II samples. While the specific interpretation of those values depends on the TEQ method used, the table expressly compares results to the West Virginia DEP Tier 1 residential soil PRG of 3.9 ng/kg (ppt) and reports concentrations orders of magnitude above that benchmark. The broader 3TM soil report likewise states that sample results indicated dioxin/furan TEQs in excess of the West Virginia DEP Tier 1 value at sampled locations.
In addition to outdoor soil, the project evaluated indoor dust as a residential exposure medium. The 3TM Phase III report explains that indoor dust was collected from 16 residences in Nitro and surrounding communities using the HVS-3 forensic vacuum sampler, a method specifically developed for environmental forensic dust sampling. The report states that dust was collected from attics and other undisturbed indoor locations because those areas can preserve historical contamination and provide a meaningful record of long-term airborne deposition and indoor accumulation. Dust samples were analyzed for dioxins/furans using EPA Method 1613B with high-resolution gas chromatography / high-resolution mass spectrometry (HRGC/HRMS).
The indoor-dust results were significant because they provided evidence that dioxin contamination was not confined to outdoor soils. The 3TM summary report states that all indoor dust samples analyzed exceeded the West Virginia DEP Tier 1 residential soil value of 3.9 ppt TEQ, that 2,3,7,8-TCDD was detected in 15 of 16 indoor dust samples, and that the spatial pattern of indoor-dust contamination generally decreased with distance from the Monsanto plant. The report further concludes that, within a reasonable degree of environmental engineering and scientific probability, the dioxin/furan contamination detected in Nitro indoor dust was attributable to the Monsanto plant rather than another source. In legacy exposure cases, indoor dust is particularly important because it represents a medium through which outdoor deposition can be transferred into occupied buildings and can create chronic exposure through incidental ingestion, dermal contact, and re-entrainment of fine particles.
The final major component was plaintiff-specific exposure reconstruction. Joel Graves’ affidavit describes a lifetime pattern of residence, work, and repeated presence at 105 Pickens Road, where his family operated Southern Lumber adjacent to the Monsanto plant gate. The affidavit states that he was present at the lumber business regularly as a child beginning at approximately age two, later worked there daily as an adult, lived in a house on the property for approximately twenty years, and remained present at 105 Pickens Road from 1950 to 2016. He also states that he entered the Monsanto plant daily or multiple times per day for deliveries and sales and that he was in and out of the “weed killer” building during its construction and operation, where he believed he was exposed to fumes and dust from the process.
This type of time-location history is critical in an environmental forensic case because it allows the technical analysis to move beyond generalized community contamination and evaluate whether a specific individual experienced repeated residential, occupational, and facility-adjacent exposure opportunities over decades. In this matter, the exposure reconstruction could reasonably include multiple pathways: inhalation of airborne contaminants during the active release period; soil contact and incidental ingestion at the Pickens Road property; indoor-dust exposure in on-site residences or buildings; and repeated direct presence near process and waste-handling areas. RoseyFields’ work in a case like this is to integrate those personal-history facts with the engineering, sampling, and fate-and-transport record to assess whether the exposure scenario is scientifically coherent and whether the contamination pattern is consistent with the individual’s claimed exposure history.
Results
The first major finding is that the historical Monsanto herbicide operations created a plausible, technically supported source of off-site dioxin contamination in Nitro. The available engineering analyses identify 2,4,5-T production as a dioxin-generating process, estimate substantial total dioxin losses during the 1948–1969 production period, and identify waste burning as the dominant atmospheric release pathway for off-site impacts. The source reconstruction and AERMOD modeling framework provide a coherent explanation for how dioxin generated at the facility could have been released to the air and transported into nearby residential and commercial areas.
The second major finding is that the environmental measurements are broadly consistent with a historical airborne deposition scenario rather than an isolated on-site contamination problem. The 3TM materials describe widespread surface-soil contamination in Nitro and report indoor-dust TEQ concentrations above the West Virginia DEP Tier 1 residential soil benchmark at sampled residences. The report also notes a general decrease in indoor-dust concentrations with increasing distance from the former Monsanto plant, a spatial pattern consistent with a facility-related airborne source. For a legacy dioxin case, that combination of historical emissions reconstruction, modeled deposition, and measured off-site soil/dust contamination is especially important because it strengthens the causal link between the former plant and the surrounding community contamination footprint.
A third key finding is that 105 Pickens Road appears to sit within the contaminated exposure zone and is directly relevant to the plaintiff-specific exposure narrative. The affidavit places Joel Graves at 105 Pickens Road and the adjacent Southern Lumber property for decades, including childhood, adult work, and long-term residence. The testing results identify 105 Pickens / lot next to 105 Pickens as a sampled location and report dioxin/furan TEQ values in surface soil far above the 3.9 ppt residential screening benchmark. Although a full causation opinion would require careful review of sampling design, TEQ methodology, and temporal limitations, the available record supports the proposition that the property associated with Graves’ residential and occupational history was not merely near the plant, but was itself part of the environmental sampling record for dioxin contamination.
A fourth major finding is methodological: legacy dioxin cases require integration of multiple lines of evidence rather than reliance on a single sampling event or a single model output. Historical facility operations, waste-burning practices, air dispersion and deposition modeling, community soil data, indoor-dust sampling, and plaintiff-specific time-location histories each capture only part of the exposure story. RoseyFields’ role in a case like this is to evaluate how those lines of evidence fit together, where they corroborate one another, and where uncertainty remains. In this matter, the convergence of facility history, modeled atmospheric transport, community contamination measurements, and a long-term residential/occupational presence near the plant creates a technically robust framework for evaluating exposure to dioxins/furans from the former Nitro herbicide operations.
Conclusions
This project illustrates RoseyFields’ ability to perform environmental forensic investigations of historical dioxin contamination involving industrial operations, air dispersion modeling, multi-media sampling, and plaintiff-specific exposure reconstruction. The Nitro matter required more than identifying that dioxins were historically associated with herbicide production. It required reconstructing historical waste-burning emissions, evaluating how those emissions would have dispersed and deposited across the surrounding valley, interpreting later soil and indoor-dust measurements, and tying those findings to the long-term residential and occupational history of an individual who lived and worked adjacent to the former facility.
The case also demonstrates the value of integrating air modeling and exposure assessment in legacy contamination matters. Historical releases rarely come with contemporaneous air monitoring or complete operational records, so the technical assessment must bridge those gaps using engineering reconstruction, deposition modeling, and environmental media that preserve evidence of past releases, such as surface soil and indoor dust. By combining those tools with property-specific sampling and time-location information, RoseyFields can evaluate whether present-day contamination patterns are consistent with historical facility emissions and whether an individual’s claimed exposure history is scientifically plausible.
More broadly, this work reflects RoseyFields’ experience in occupational and community exposure assessment for persistent organic pollutants, especially where contamination from historic industrial operations extends beyond the plant boundary and into homes, businesses, and other occupied environments. Whether the question involves dioxins, PFAS, metals, combustion byproducts, or other persistent contaminants, RoseyFields can integrate source reconstruction, fate-and-transport analysis, environmental sampling, and exposure science into a defensible technical framework for litigation support and environmental forensic evaluation.
Dr. Paul Rosenfeld led the technical evaluation of historical dioxin contamination and exposure pathways for this matter, applying environmental forensics, air-dispersion modeling principles, surface-soil and indoor-dust interpretation, and human exposure assessment to evaluate how legacy releases from a herbicide manufacturing facility could affect nearby residents and workers. His work focused on integrating historical manufacturing and waste-management records, deposition and transport mechanisms, environmental sampling data, and plaintiff-specific residential and occupational histories into a defensible assessment of dioxin fate, transport, and long-term human exposure. The project reflects Dr. Rosenfeld’s broader expertise in industrial contamination investigations, persistent organic pollutants, exposure reconstruction, and risk evaluation for legacy chemical releases in residential, occupational, and community settings.
References
Auberle, W. M. (2010, February). Fate and transport of dioxin emissions from Monsanto Company, Nitro, West Virginia during the period 1948–1969.
3TM International, Inc. (2006, November 17). Phase III data report: Field sampling and analytical testing, Nitro, West Virginia and surrounding area.
U.S. Environmental Protection Agency. (2017 archived snapshot; site last updated September 2016). Hazardous waste cleanup: Solutia Nitro Site (formerly Flexsys, Solutia, Monsanto), Nitro, West Virginia.