Environmental Forensic Investigation of Historical Landfill Contamination, Contaminant Transport, and Community Exposure Assessment
Project Overview
This environmental forensic investigation evaluated historical contamination associated with a former industrial landfill that accepted municipal and industrial wastes over multiple decades. The objective was to reconstruct historical waste disposal practices, characterize contaminants present at the site and in adjacent residential areas, evaluate environmental transport pathways, and assess potential human exposure using historical records, environmental sampling, regulatory documentation, and scientific literature. The investigation integrated environmental chemistry, contaminant fate and transport, exposure science, and regulatory review to develop a comprehensive understanding of historical environmental conditions.
A multidisciplinary approach was used to evaluate how contaminants released from historical waste disposal activities may have migrated beyond the landfill boundary into surrounding communities. The investigation reviewed historical remedial investigation reports, environmental sampling data, groundwater investigations, soil chemistry, indoor dust sampling, and published scientific literature addressing contaminant persistence, environmental transport, and human exposure. By combining multiple independent lines of evidence, the investigation reconstructed likely exposure pathways while accounting for uncertainties commonly encountered during historical environmental investigations.
Unlike investigations focused on a single chemical or release event, this project addressed complex mixtures of persistent contaminants originating from numerous historical industrial activities. The investigation therefore emphasized evaluating cumulative contaminant behavior, multiple environmental media, and overlapping transport mechanisms rather than considering each contaminant independently. This approach reflects accepted environmental forensic practices for assessing legacy contamination at former industrial waste disposal sites.
Chemicals of Concern
The investigation focused on numerous persistent organic pollutants (POPs), chlorinated organic compounds, petroleum-related chemicals, metals, and other hazardous substances historically associated with industrial waste disposal. Historical records indicated disposal of municipal refuse together with industrial wastes containing chlorinated pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), metals, fly ash, laboratory wastes, plating sludge, graphite residues, and other industrial byproducts.
Particular attention was given to persistent organic pollutants because of their resistance to environmental degradation, ability to bioaccumulate, and potential for long-range environmental transport. These compounds included chlorinated pesticides such as DDT, DDE, DDD, aldrin, dieldrin, chlordane, heptachlor, toxaphene, lindane, hexachlorobenzene, polychlorinated biphenyls, dioxins, and furans. Scientific literature has demonstrated that many of these contaminants remain in soils and sediments for decades after their original release, making them important chemicals of concern during historical environmental investigations.
The investigation also evaluated heavy metals including arsenic, lead, mercury, cadmium, copper, and barium. These metals are frequently associated with industrial waste disposal and combustion residues and may remain within surface soils, groundwater, and sediments long after disposal activities have ceased. Additional contaminants of concern included benzene, toluene, chlorinated solvents, chlorobenzenes, phenols, phthalates, and other volatile and semi-volatile organic compounds identified during historical environmental investigations.
Because historical industrial disposal frequently involved complex mixtures rather than individual chemicals, the investigation also considered scientific literature evaluating the combined effects of persistent organic pollutant mixtures. Published research indicates that mixtures of chlorinated compounds, pesticides, and PCBs may exhibit cumulative toxicological behavior and therefore warrant evaluation as integrated contaminant groups rather than isolated compounds.
Methods
The investigation employed accepted environmental forensic methods to reconstruct historical contamination and evaluate potential exposure pathways. Historical regulatory reports, remedial investigation documents, engineering studies, environmental sampling results, and scientific publications were reviewed to establish site history, identify waste sources, characterize contaminant distributions, and evaluate historical environmental conditions. This comprehensive document review was supplemented by evaluation of contaminant chemistry, transport mechanisms, and published toxicological information.
Environmental sampling data from soil, groundwater, observation wells, and residential media were evaluated to identify contaminants exceeding applicable regulatory criteria. Soil chemistry was compared with representative background concentrations and published cleanup objectives to assess the spatial distribution of contamination and distinguish site-related contamination from naturally occurring background conditions. Review of contaminant occurrence across multiple environmental media provided insight into the persistence and migration of hazardous substances over time.
The investigation also evaluated contaminant transport through multiple environmental pathways. Particular emphasis was placed on groundwater migration, surface runoff, airborne dust, indoor dust accumulation, soil transport, and the influence of nonaqueous phase liquids (NAPL) and dense nonaqueous phase liquids (DNAPL). Because these dense organic liquids may migrate independently of groundwater flow and penetrate preferential pathways within subsurface materials, understanding their behavior was essential for evaluating long-term contaminant migration and remediation challenges.
Indoor dust exposure represented another important component of the investigation. Published guidance from the Agency for Toxic Substances and Disease Registry (ATSDR) recognizes indoor dust as a significant exposure pathway that should be evaluated together with soil ingestion, particularly in residential settings. The investigation therefore considered indoor dust concentrations, contaminant adsorption to fine particles, historical occupational studies involving settled dust, and established soil and dust ingestion assumptions when evaluating potential community exposures.
Scientific literature describing persistent organic pollutants, environmental persistence, bioaccumulation, mixture toxicology, and contaminant transport was incorporated throughout the evaluation to support interpretation of sampling results and historical environmental conditions. Integrating field observations with peer-reviewed scientific literature strengthened the technical basis of the investigation and provided additional context for evaluating long-term environmental contamination.
Results
Review of the historical information demonstrated that the former disposal area received a broad range of municipal and industrial wastes containing persistent organic pollutants, metals, petroleum-related compounds, chlorinated solvents, combustion byproducts, and other hazardous materials over an extended operational period. Environmental investigations identified contaminants in surface soils, subsurface soils, groundwater, and observation wells that exceeded applicable regulatory criteria, indicating the presence of widespread historical contamination affecting multiple environmental media.
The investigation found that persistent organic pollutants represented a particularly significant component of historical contamination. Numerous chlorinated pesticides, PCBs, dioxins, furans, and related compounds were documented in environmental samples. Because these chemicals degrade slowly, bioaccumulate within biological systems, and may be transported through soil, groundwater, sediment, dust, and surface water, they remain important contaminants during long-term environmental investigations.
Historical data further demonstrated that contamination involved mixtures of hazardous chemicals rather than isolated compounds. Scientific literature reviewed during the investigation indicates that exposure to mixtures of persistent organic pollutants may produce biological responses that differ from exposures to individual chemicals alone. This underscores the importance of evaluating cumulative contaminant behavior when assessing legacy industrial sites.
Another significant finding involved the role of NAPL and DNAPL in contaminant migration. Historical investigations documented dense organic liquids within portions of the site, indicating the potential for complex subsurface transport behavior. Unlike dissolved contaminants transported primarily through groundwater, dense nonaqueous phase liquids may migrate through preferential pathways, penetrate low-permeability materials, and continue serving as long-term contaminant sources. These characteristics complicate site characterization and often increase the difficulty of remediation.
The investigation also highlighted the importance of indoor dust as an exposure pathway. Published federal guidance recognizes that soil and indoor dust ingestion are closely related exposure mechanisms, particularly for residential populations. Historical occupational studies and environmental health guidance support evaluation of settled dust as an indicator of long-term contaminant exposure, reinforcing the need to consider multiple exposure pathways when evaluating legacy contamination.
Collectively, the environmental data demonstrated that historical industrial disposal practices may create persistent contamination affecting soil, groundwater, indoor dust, and surrounding residential environments for decades after disposal activities have ceased. These findings illustrate the value of integrating historical records, environmental sampling, contaminant transport analyses, and scientific literature within a comprehensive environmental forensic investigation.
Conclusions
This investigation demonstrates how environmental forensic science can be applied to reconstruct historical contamination associated with former industrial landfills and evaluate potential community exposure through multiple environmental pathways. By integrating historical operational records, environmental sampling, groundwater investigations, contaminant chemistry, toxicology, and regulatory guidance, investigators can develop a scientifically supported understanding of contaminant sources, migration mechanisms, and long-term environmental conditions.
The project also illustrates the importance of evaluating contaminant mixtures rather than individual chemicals in isolation. Former industrial disposal sites frequently contain persistent organic pollutants, chlorinated compounds, petroleum-related contaminants, metals, and other hazardous substances that interact across multiple environmental media. Considering these contaminants collectively provides a more realistic representation of historical environmental conditions and potential exposure scenarios.
Finally, the investigation highlights the value of multidisciplinary environmental forensic methods for addressing complex historical contamination. Combining environmental chemistry, contaminant fate and transport, hydrogeology, exposure assessment, toxicology, and regulatory analysis allows historical industrial activities to be reconstructed in a technically defensible manner while supporting informed decision-making regarding environmental characterization and remediation.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and President of RoseyFields LLC with more than 30 years of experience in environmental consulting, forensic investigations, and exposure assessment. Dr. Rosenfeld specializes in evaluating complex environmental contamination cases involving hazardous waste sites, industrial facilities, landfills, air emissions, groundwater contamination, and historical releases of hazardous substances. His expertise includes contaminant fate and transport, environmental chemistry, air dispersion modeling, risk assessment, exposure reconstruction, and the interpretation of environmental sampling data.
References
Agency for Toxic Substances and Disease Registry. (2005). Public health assessment guidance manual. U.S. Department of Health and Human Services. https://www.atsdr.cdc.gov
Agency for Toxic Substances and Disease Registry. (2018). ATSDR soil and sediment ingestion guidance. U.S. Department of Health and Human Services. https://www.atsdr.cdc.gov
Amber, K. T., Bloomer, R. J., & colleagues. (2021). Effects of defined mixtures of persistent organic pollutants (POPs) on pre-lethal cytotoxicity in the human A-498 kidney cell line in vitro. Exposure and Health, 13, 465–475.
Davidsen, N., et al. (2021). Exposure to human relevant mixtures of halogenated persistent organic pollutants alters neurodevelopmental processes in human neural stem cells undergoing differentiation. Reproductive Toxicology, 100, 17–34. https://doi.org/10.1016/j.reprotox.2020.12.013
New York State Department of Environmental Conservation. (2019). Remedial investigation report: Former municipal landfill site. New York State Department of Environmental Conservation.
Ouidir, M., et al. (2020). Association of maternal exposure to persistent organic pollutants in early pregnancy with fetal growth. JAMA Pediatrics, 174(2), 149–161. https://doi.org/10.1001/jamapediatrics.2019.5104
U.S. Environmental Protection Agency. (1991). Dense nonaqueous phase liquids (DNAPL): Groundwater issue(EPA/540/4-91-002). Office of Solid Waste and Emergency Response.
U.S. Environmental Protection Agency. (2003). World Trade Center indoor environmental assessment: Selecting contaminants of potential concern and setting health-based benchmarks. U.S. Environmental Protection Agency.
U.S. Environmental Protection Agency. (2023). Persistent organic pollutants (POPs). https://www.epa.gov/international-cooperation/persistent-organic-pollutants-global-issue
U.S. Environmental Protection Agency. (2023). Hazardous waste cleanup information and chlor-alkali industry resources. https://www.epa.gov