Environmental Forensic Investigation of Indoor Air Quality, PCB Exposure Assessment, Building Material Evaluation, and Human Health Risk Assessment in an Educational Facility
Project Overview
Indoor environmental quality investigations have become increasingly important in older educational and public buildings following the recognition that certain construction materials manufactured prior to the federal phase-out of polychlorinated biphenyls (PCBs) may continue to release these compounds into indoor environments decades after installation. PCBs were widely incorporated into caulks, sealants, paints, electrical equipment, fluorescent light ballasts, and other building materials because of their chemical stability and insulating properties. Although their manufacture was prohibited in the United States in 1979, many older buildings continue to contain legacy PCB-containing materials that can slowly emit contaminants into indoor air and dust, creating potential long-term exposure for building occupants (U.S. EPA, 2024a; ATSDR, 2000).
This environmental forensic investigation evaluated historical PCB exposure within an educational facility constructed before the federal phase-out of PCB-containing building materials. The primary objective was to determine whether legacy building materials contributed to elevated indoor PCB concentrations and whether historical occupancy could have resulted in meaningful inhalation and dust exposure over extended periods. Rather than relying on a single dataset, the investigation integrated indoor air sampling, environmental chemistry, building science, exposure assessment, environmental sampling, toxicological literature, engineering evaluations, and human health risk assessment to reconstruct historical indoor environmental conditions. This multidisciplinary approach provided a scientifically rigorous framework for evaluating contaminant sources, exposure pathways, and potential human health risks associated with long-term occupancy of aging buildings (U.S. EPA, 2024b; World Health Organization, 2021).
A major component of the investigation focused on identifying potential PCB sources within the building and understanding how building characteristics influenced contaminant distribution. Historical construction records, building material inventories, renovation histories, ventilation characteristics, and indoor air sampling data were evaluated to determine how legacy materials may have contributed to indoor PCB concentrations. Because renovations may remove, encapsulate, or disturb PCB-containing materials, evaluating changes in building configuration and material replacement was an important part of reconstructing historical exposure conditions. Building science principles were integrated with environmental sampling data to better understand the relationship between contaminant sources, air movement, and occupant exposure (MacIntosh et al., 2012; U.S. EPA, 2024a).
The investigation also evaluated multiple exposure pathways associated with PCB contamination. Indoor air inhalation was considered the principal pathway because PCBs slowly volatilize from certain building materials over time. However, airborne PCBs may also adsorb to settled dust and interior surfaces, creating additional opportunities for exposure through incidental dust ingestion and secondary inhalation when indoor dust is disturbed. Consequently, evaluating both airborne concentrations and dust-related exposure provided a more comprehensive assessment than considering indoor air alone. Established exposure assessment methodologies were applied to estimate cumulative lifetime exposure using representative occupancy patterns and accepted toxicological assumptions (ATSDR, 2000; U.S. EPA, 1989).
Finally, this environmental forensic investigation integrated environmental chemistry, indoor air quality assessment, building science, contaminant fate and transport, exposure reconstruction, toxicology, and human health risk assessment into a unified scientific framework. By combining multiple independent lines of evidence rather than relying upon any individual measurement, the investigation developed a technically defensible assessment of historical PCB exposure suitable for environmental consulting, environmental litigation, regulatory investigations, indoor environmental quality evaluations, and expert witness testimony. This multidisciplinary approach reflects current best practices for investigating legacy contaminants in older buildings while supporting science-based decision-making regarding risk management and remediation (Morrison & Murphy, 2010; U.S. EPA, 2024b).
Chemicals of Concern
The primary contaminant evaluated during this environmental forensic investigation was polychlorinated biphenyls (PCBs), a class of synthetic chlorinated organic compounds historically manufactured for use in electrical equipment and numerous building materials because of their chemical stability, fire resistance, and insulating properties. Prior to the federal prohibition on PCB manufacture in 1979, these compounds were incorporated into caulks, sealants, paints, adhesives, fluorescent light ballasts, transformers, and other construction materials commonly used in schools, commercial buildings, and public facilities. Although production ceased decades ago, many older buildings continue to contain legacy PCB-containing materials capable of slowly releasing these compounds into indoor environments through volatilization and weathering, making PCBs one of the most important contaminants encountered during indoor environmental investigations (ATSDR, 2000; U.S. EPA, 2024a).
Unlike many volatile organic compounds that dissipate relatively quickly following installation, PCBs can remain within building materials for many decades while continuously emitting low concentrations into indoor air. The rate of emission depends upon numerous factors including the original PCB concentration, material composition, age, temperature, ventilation, and the condition of the building material itself. As materials deteriorate or are disturbed during renovation or maintenance activities, PCB emissions may increase, resulting in elevated indoor air concentrations and contamination of interior dust. Consequently, evaluating the condition, location, and distribution of suspect building materials represents an essential component of environmental forensic investigations involving legacy PCB contamination (MacIntosh et al., 2012; Herrick et al., 2004).
Indoor air inhalation is generally considered the primary exposure pathway for PCB contamination originating from building materials. As PCBs slowly volatilize into indoor air, occupants may inhale these compounds during routine occupancy over extended periods. Airborne PCBs may also adsorb onto airborne particulate matter and settle onto indoor surfaces where they become incorporated into household or classroom dust. Disturbance of settled dust through routine activities—including cleaning, maintenance, or normal occupant movement—can reintroduce contaminated particles into the breathing zone while also creating opportunities for incidental dust ingestion. Because these exposure pathways occur simultaneously, comprehensive environmental investigations typically evaluate both airborne PCB concentrations and dust-related exposures when assessing cumulative human exposure (ATSDR, 2000; U.S. EPA, 1989).
PCBs have been extensively studied because of their persistence, bioaccumulation, and potential adverse health effects. The International Agency for Research on Cancer (IARC) classifies PCBs as carcinogenic to humans (Group 1) based on sufficient evidence linking exposure to several forms of cancer. In addition to carcinogenicity, toxicological and epidemiological studies have associated PCB exposure with adverse effects involving the immune system, nervous system, endocrine system, liver, reproductive system, thyroid function, and neurodevelopment. Developing children are considered particularly sensitive because exposure during critical periods of development may affect learning, behavior, and cognitive performance. These well-established toxicological characteristics make PCB exposure an important consideration during investigations involving older educational facilities and other public buildings constructed before the federal phase-out of PCB-containing materials (IARC, 2016; ATSDR, 2000; World Health Organization, 2021).
Because PCB concentrations within buildings may vary substantially from room to room depending on building materials, renovation history, ventilation characteristics, and occupancy patterns, environmental forensic investigations require integration of building science, environmental chemistry, indoor air quality assessment, exposure science, and toxicology. Evaluating contaminant sources together with indoor air sampling, dust accumulation, building ventilation, and historical occupancy provides a more comprehensive understanding of long-term exposure than any individual dataset considered alone. This multidisciplinary framework supports scientifically rigorous evaluations of indoor environmental quality, human exposure, remediation planning, environmental consulting, regulatory investigations, and expert witness testimony involving legacy PCB contamination in older buildings (Morrison & Murphy, 2010; U.S. EPA, 2024b).
Methods
This environmental forensic investigation employed a multidisciplinary methodology integrating building science, environmental chemistry, indoor air quality assessment, exposure science, environmental sampling, contaminant fate and transport evaluation, toxicology, epidemiology, and human health risk assessment. Because legacy PCB contamination within buildings often results from multiple construction materials, varying renovation histories, and complex indoor air dynamics, the investigation adopted a weight-of-evidence approach that combined historical building information, indoor air sampling, building material evaluations, exposure reconstruction, and published scientific literature to characterize contaminant sources and estimate long-term human exposure. This integrated methodology is widely accepted within environmental forensics because it provides a more scientifically defensible assessment than reliance on any individual dataset or sampling event alone (Morrison & Murphy, 2010; U.S. EPA, 2024a).
The investigation began with a comprehensive review of historical building information, construction records, renovation histories, and building material inventories to identify potential sources of PCB contamination. Particular attention was given to materials historically known to contain PCBs, including caulks, sealants, paints, adhesives, electrical components, and fluorescent lighting systems. Building age, renovation activities, and the distribution of suspect materials were evaluated to determine how historical construction practices could influence present-day indoor PCB concentrations. Understanding the location and condition of these legacy materials provided the foundation for evaluating contaminant sources and developing representative indoor air sampling strategies (U.S. EPA, 2024a; Herrick et al., 2004).
Indoor air quality was evaluated using representative sampling methods designed to characterize airborne PCB concentrations throughout occupied portions of the building. Sampling locations were selected to represent areas with similar construction characteristics, building materials, occupancy patterns, and ventilation conditions. Air samples were collected over extended sampling periods using calibrated low-flow sampling equipment and laboratory-certified analytical methods capable of measuring low-level PCB concentrations in indoor air. Quality assurance and quality control procedures—including calibration verification, duplicate sampling, field blanks, and standardized laboratory analyses—were incorporated to ensure that sampling results were scientifically reliable and suitable for quantitative exposure assessment (U.S. EPA, 2013; ASTM International, 2019).
Building science evaluations were conducted alongside indoor air sampling to assess how ventilation characteristics, room configuration, air movement, and historical renovations influenced contaminant distribution. Because indoor PCB concentrations may vary depending on airflow patterns, HVAC operation, temperature, and the presence of legacy building materials, these factors were evaluated together rather than independently. Assessing building characteristics alongside environmental sampling allowed investigators to better distinguish potential contaminant sources, understand spatial variability within the building, and identify factors influencing occupant exposure (MacIntosh et al., 2012; Batterman et al., 2012).
Human exposure was evaluated by integrating indoor air concentrations with established exposure assessment methodologies developed by the U.S. Environmental Protection Agency. Multiple exposure pathways—including inhalation of indoor air and incidental ingestion of contaminated indoor dust—were evaluated using representative occupancy assumptions and published toxicological parameters. Lifetime cancer risk and non-cancer hazard were estimated using accepted risk assessment methodologies together with peer-reviewed toxicological literature. Integrating building science, indoor air quality, environmental chemistry, exposure reconstruction, and toxicology provided a scientifically rigorous framework for evaluating historical PCB exposure, identifying contaminant pathways, and supporting environmental consulting, indoor environmental quality investigations, remediation planning, regulatory evaluations, and expert witness testimony involving legacy PCB contamination in older buildings (U.S. EPA, 1989; U.S. EPA, 2024b; ATSDR, 2000).
Results
The environmental forensic investigation demonstrated that integrating building science, indoor air quality assessment, environmental chemistry, exposure science, and human health risk assessment provided a comprehensive framework for evaluating historical PCB contamination within an older educational facility. Rather than relying on a single sampling event or isolated analytical result, the investigation synthesized historical building information, indoor air measurements, building material evaluations, and exposure reconstruction to characterize contaminant sources and assess potential long-term occupant exposure. Collectively, these independent lines of evidence demonstrated that legacy PCB-containing building materials can remain important contributors to indoor air contamination decades after installation and that evaluating building characteristics alongside environmental sampling substantially improves understanding of contaminant distribution and exposure (Morrison & Murphy, 2010; U.S. EPA, 2024a).
Indoor air sampling identified measurable PCB concentrations throughout portions of the building, demonstrating that airborne PCB contamination may occur even in facilities that have undergone partial renovations or modernization. Variability among sampled locations reflected differences in building age, renovation history, remaining legacy materials, ventilation characteristics, and room-specific construction features. These findings are consistent with previous investigations demonstrating that indoor PCB concentrations often vary considerably within the same building depending upon the distribution and condition of PCB-containing materials rather than building age alone (MacIntosh et al., 2012; Herrick et al., 2004).
Building science evaluations further demonstrated that historical renovations can substantially influence indoor contaminant distribution without necessarily eliminating all potential PCB sources. While renovation activities may remove or encapsulate certain PCB-containing materials, original construction materials often remain concealed within walls, ceilings, flooring systems, utility spaces, or mechanical systems. Consequently, buildings containing both original and renovated components may exhibit complex spatial patterns of indoor PCB concentrations. Evaluating renovation history together with building material inventories and indoor air sampling therefore provided important context for interpreting environmental measurements and identifying potential contaminant sources (U.S. EPA, 2024a; Batterman et al., 2012).
Exposure assessment demonstrated that indoor air inhalation represented the primary route of PCB exposure, while contaminated indoor dust provided an additional pathway contributing to cumulative exposure. Airborne PCBs released from building materials may adsorb to settled dust, which can subsequently be redistributed through normal occupant activity, routine cleaning, or maintenance operations. This interaction between indoor air and settled dust illustrates why comprehensive exposure assessments should evaluate multiple exposure pathways rather than relying exclusively on airborne concentrations. Integrating indoor air quality data with exposure science provided a more realistic estimate of long-term occupant exposure and supported evaluation of both cancer and non-cancer health risks using established risk assessment methodologies (ATSDR, 2000; U.S. EPA, 1989).
Review of the toxicological and epidemiological literature further demonstrated that chronic PCB exposure has been associated with a range of adverse health outcomes, particularly following long-term exposure in indoor environments. Although individual health risks depend upon exposure duration, concentration, age, and other factors, regulatory agencies recognize that reducing long-term PCB exposure is an important public health objective, particularly within schools and other buildings occupied by children. Integrating toxicological evidence with environmental sampling and exposure reconstruction therefore strengthened the scientific basis for evaluating potential health implications associated with legacy PCB contamination (IARC, 2016; World Health Organization, 2021).
Overall, the investigation demonstrated that historical PCB contamination in older buildings is most accurately evaluated using a multidisciplinary environmental forensic approach that integrates building science, environmental chemistry, indoor air quality assessment, environmental sampling, exposure reconstruction, toxicology, and risk assessment. The consistency observed among these independent lines of scientific evidence provided a technically rigorous basis for evaluating contaminant sources, characterizing long-term indoor exposure, and supporting environmental consulting, indoor environmental quality investigations, remediation planning, regulatory decision-making, and expert witness evaluations involving legacy PCB contamination.
Conclusions
This environmental forensic investigation demonstrates that evaluating legacy PCB contamination in older buildings requires a multidisciplinary scientific approach integrating building science, environmental chemistry, indoor air quality assessment, environmental sampling, exposure science, toxicology, epidemiology, and human health risk assessment. Because PCBs may remain within building materials for decades after installation, understanding historical exposure requires more than isolated sampling results. Instead, integrating multiple independent lines of evidence—including historical building information, environmental measurements, engineering evaluations, and published scientific literature—provides a more reliable and scientifically defensible framework for characterizing contaminant sources, reconstructing exposure, and assessing potential health risks (Morrison & Murphy, 2010; U.S. EPA, 2024a).
A principal finding of the investigation was the importance of building materials and building science in controlling indoor PCB concentrations. Legacy construction materials installed before the federal phase-out of PCBs can continue to emit low concentrations into indoor environments over extended periods, particularly where original materials remain following partial renovations. Evaluating construction history, renovation activities, ventilation characteristics, and the distribution of suspect materials alongside environmental sampling significantly improves identification of contaminant sources and interpretation of indoor air quality data. This integrated approach is now recognized as a best practice for investigating PCB contamination in aging buildings (Herrick et al., 2004; U.S. EPA, 2024a).
The investigation also demonstrated the importance of evaluating multiple exposure pathways rather than relying solely on indoor air measurements. Although inhalation generally represents the dominant pathway for PCB exposure within buildings, airborne PCBs may accumulate on indoor surfaces and within settled dust, creating additional opportunities for exposure through incidental dust ingestion and secondary inhalation. Considering these pathways together provides a more realistic estimate of cumulative exposure and better reflects the complex behavior of persistent contaminants within indoor environments. This comprehensive exposure assessment framework supports more accurate evaluations of both cancer and non-cancer health risks (ATSDR, 2000; U.S. EPA, 1989).
Another important conclusion is the value of integrating environmental sampling with exposure assessment and toxicology. Environmental measurements document the presence and distribution of contaminants, while exposure assessment places those measurements into the context of real-world building occupancy and human behavior. When combined with toxicological and epidemiological evidence, these complementary disciplines provide a scientifically robust basis for evaluating potential health implications associated with long-term PCB exposure. Such multidisciplinary analyses improve confidence in environmental forensic investigations and support informed decisions regarding building management, remediation, and long-term risk reduction (IARC, 2016; World Health Organization, 2021).
Overall, this investigation illustrates how environmental forensic science can be applied to evaluate legacy contaminants in aging buildings using established scientific principles and accepted regulatory methodologies. By integrating building science, indoor air quality assessment, environmental chemistry, contaminant fate and transport, exposure reconstruction, toxicology, and human health risk assessment, investigators can objectively characterize historical environmental conditions and evaluate potential exposure while reducing uncertainty through multiple independent lines of scientific evidence. This multidisciplinary approach provides valuable technical support for environmental consulting, indoor environmental quality investigations, remediation planning, regulatory compliance, and expert witness services involving persistent indoor environmental contaminants.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and expert in environmental forensics, exposure assessment, air quality, and human health risk evaluation. Dr. Rosenfeld’s extensive experience applying these methods to real-world contamination cases, particularly in analyzing indoor air quality, reconstructing chemical exposures, and evaluating contaminant behavior, directly informs his ability to assess the conditions and risks presented in this case.
References
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