PCB Indoor Air Exposure Assessment and Human Health Risk Evaluation in a Contaminated School Building
Project Overview
RoseyFields conducted a technical human-health risk assessment addressing polychlorinated biphenyls (PCBs) in indoor air and settled dust at an occupied school campus where legacy PCB-containing building materials had contaminated the indoor environment. The project focused on whether teachers and staff experienced elevated cancer and noncancer risks from long-term exposure to airborne and dust-associated PCBs emitted from aging building materials. The assignment required integrating environmental sampling data, building-specific occupancy information, toxicological benchmarks, and school-specific exposure scenarios into a defensible evaluation of exposure and risk. Rather than treating the matter as a simple indoor-air exceedance question, the work evaluated the full indoor exposure pathway: emission of PCBs from primary building materials, partitioning of PCB vapors and congeners within indoor air, transfer to surfaces and settled dust, and repeated inhalation and incidental ingestion by school occupants over multiple years. The underlying risk-assessment materials describe the assignment as an evaluation of staff exposure at Burlington High School, where employees were alleged to have been exposed to excessive PCB concentrations via indoor-air inhalation and dust ingestion, with updated supplemental analysis not changing the overall risk conclusions.
The factual setting involved a large public high school campus composed of multiple connected buildings constructed in the 1960s, later found to contain PCB-bearing building materials and elevated PCB concentrations in indoor air, dust, and other media. Available reports describe PCBs in caulk, glazing materials, mastics, flooring-related materials, spray-applied fireproofing, and other building components, with the school ultimately undergoing large-scale investigation, air testing, occupancy restrictions, and remedial planning. The 2020 Fuss & O’Neill indoor air sampling report states that the Burlington High School buildings contained PCB source materials throughout interior common spaces and at exterior windows and doors, and that indoor air concentrations exceeded Vermont’s 15 ng/m³ screening value in each building, with the highest measured indoor-air concentration reported at approximately 6,300 ng/m³ in Building F. The report also notes that students were relocated and that planning for interim and long-term remedial measures was underway in coordination with school, state, and federal agencies.
This project was therefore not simply a review of sampling results; it was a forensic exposure and risk reconstruction. RoseyFields evaluated how measured PCB concentrations in air and dust translated into actual exposure for identified school employees, how those exposures compared to toxicological benchmarks and accepted risk-management targets, and whether the resulting hazard and cancer risk estimates supported the conclusion that staff were subjected to unreasonable exposure. The work drew on school air sampling reports, Vermont Department of Health screening and action-level guidance, EPA PCB exposure-estimation methodology, building-material and source-characterization information, staff declarations describing work patterns within specific school buildings, and plaintiff-specific exposure assumptions used to estimate both cancer and noncancer risk. The resulting analysis is representative of RoseyFields’ work at the intersection of indoor environmental contamination, building-science exposure pathways, and chemical-specific human-health risk assessment.
Chemicals of Concern
The principal chemicals of concern in this matter were polychlorinated biphenyls (PCBs), a class of chlorinated organic compounds historically used in numerous industrial and commercial products because of their thermal stability, dielectric properties, and chemical resistance. In the built environment, PCBs are commonly associated with legacy caulks, sealants, glazing compounds, electrical components, paints, mastics, and other construction materials used in buildings constructed or renovated during the mid-twentieth century. PCBs are environmentally persistent, can migrate from solid materials into indoor air and settled dust, and are associated with both carcinogenic and noncancer health effects. The underlying risk-assessment and supplemental materials describe PCBs at Burlington High School as toxic chemicals released from building materials into indoor air and dust, while the Vermont and EPA materials relied on in the case use Aroclor 1254toxicity values as the basis for indoor-school-air screening and action levels.
From a toxicological standpoint, the project treated PCBs as chemicals capable of producing both cancer risk and systemic noncancer toxicity. The Vermont Department of Health’s school guidance and EPA’s PCB exposure-estimation framework use an oral reference dose (RfD) for Aroclor 1254 to evaluate noncancer risk in school occupants, while the risk-assessment materials also frame PCB exposure as presenting potential carcinogenic risk. The Vermont screening-value document explicitly states that the indoor-air screening value for school air was developed to be protective of both cancer and noncancer health effects for children and staff, and the action-level materials explain that school action levels (SALs) were derived using EPA’s exposure-estimation approach while accepting somewhat higher cancer risk than the 15 ng/m³ screening value in order to prioritize remediation and occupancy decisions.
Methods
The first analytical step was reconstructing the indoor PCB exposure pathway within the school environment. This required identifying likely primary PCB sources in the buildings, understanding how those sources emitted PCBs into indoor air, and determining how those emissions could create both inhalation and incidental dust-ingestion exposures for staff and other occupants. The Burlington High School materials indicate that PCB contamination at the school was attributed to multiple building materials, including caulk and glazing compounds and other visible and concealed building components. The supplemental risk-assessment materials state that the presence of PCBs on the BHS campus was attributed to materials such as caulking, mastic flooring, spray-on fireproofing, and capacitors, and that PCBs released from these materials could contaminate indoor air through off-gassing and contribute to indoor dust, creating inhalation and ingestion risks.
RoseyFields also reviewed literature and project-specific reports describing the behavior of PCBs once emitted indoors. The risk-assessment materials summarize the now well-established pathway in which PCBs emitted from caulk or similar source materials enter indoor air in the vapor phase, are inhaled directly by occupants, and can also deposit onto surfaces or partition into settled dust, creating a secondary exposure reservoir. The EH&E report on Burlington High School likewise includes extended discussion of PCB behavior in the indoor environment, emission from source materials, partitioning between air and surfaces, and transport into settled dust. This pathway mattered because the exposure assessment was not limited to inhalation of vapor-phase PCBs; it also considered dust ingestion as a meaningful route of exposure for school staff who spent years in contaminated classrooms and offices.
The next component of the project was review of the available building-material, indoor-air, and dust sampling datagenerated during the school investigation. Burlington High School had already undergone substantial environmental testing before the plaintiff-specific risk analysis. According to the available records, Atlas Technical Consultants initially surveyed building materials in 2019–2020 to identify PCB-containing materials associated with a planned renovation and demolition project. Those findings led to further involvement by Fuss & O’Neill, agency consultation, and a 2020 indoor-air sampling campaign across the school’s buildings. The Fuss & O’Neill indoor-air report states that air sampling was conducted in September 2020 within Buildings A through F following agency review of the sampling plan and that the purpose of the work was to evaluate whether PCBs found in source materials were contributing to PCB levels in indoor school air.
The available sampling results established that the school had widespread indoor-air contamination rather than a single isolated room with elevated concentrations. Fuss & O’Neill reported exceedances of the Vermont Department of Health screening concentration of 15 ng/m³ in each Burlington High School building, with Building F showing the highest concentrations. The same report identified a maximum indoor-air concentration of roughly 6,300 ng/m³ in Building F and a second-highest concentration of 5,800 ng/m³ in an adjacent Building F shop room. The supplemental risk materials also state that PCBs were measured in indoor air, outdoor air, dust, and building materials at BHS and that air concentrations reached 6,330.23 ng/m³ while dust concentrations reached 1,740 mg/kg. These concentrations are notable not only because they exceeded Vermont’s health-based screening value by orders of magnitude, but also because they demonstrated that PCB contamination was present in multiple environmental media relevant to staff exposure.
Because this case involved school occupancy rather than an industrial workplace, RoseyFields evaluated the sampling results and plaintiff exposures against school-specific PCB risk benchmarks developed by Vermont and EPA. Vermont’s 2020 school-air screening-value document established a 15 ng/m³ screening value for PCBs in school air, intended to be protective of both cancer and noncancer health effects for children and staff. The document explains that this screening value is based on a reasonable maximum exposure scenario and can be used as an indicator of when schools may have potential indoor PCB sources. Vermont later developed school action levels (SALs) and short-term occupancy guidance to prioritize response actions when school air concentrations exceeded the screening value. Those SALs were set at 30 ng/m³ for pre-kindergarten, 60 ng/m³ for kindergarten through sixth grade, and 100 ng/m³ for seventh grade through adult occupants. The short-term occupancy guidance explains that the SALs are derived from noncancer health effects and reasonable maximum exposure assumptions for students and staff, and that they correspond to a hazard quotient (HQ) of 1, while an immediate action level corresponds to an HQ of 3.
RoseyFields also reviewed the EPA PCB Exposure Estimation Tool (PEET) and the Vermont action-level derivation documents because those sources provided the methodological basis for estimating noncancer risk in school occupants. The Vermont SAL development document explains that EPA developed PEET to estimate total PCB exposure in school-age populations by incorporating inhalation, incidental dust and soil ingestion, dermal contact with dust, diet, and non-school background exposures. The model calculates the maximum school-air concentration that will keep total PCB dose below the Aroclor 1254 oral reference dose. Vermont adopted the PEET framework but modified it to derive school action levels and account for source allocation and other policy considerations. These materials were important to RoseyFields’ analysis because they show how PCB risk in schools is commonly evaluated: not by looking at air concentrations in isolation, but by linking school air and dust concentrations to total dose and hazard quotient calculations.
A central feature of the project was that it did not stop at school-wide screening or action levels. Instead, RoseyFields performed plaintiff-specific risk assessments for identified staff members based on their actual work histories, building assignments, and time spent in different areas of the campus. The July 31, 2024 risk report and the November 7, 2024 supplemental materials explain that the analysis was updated when revised declaration information was provided for one plaintiff, including revised information about the buildings in which she worked, how long she spent in each building, and additional meetings or visits to other classrooms. The supplemental materials also note that the revised analysis did not change the overall risk conclusions.
The plaintiff declarations and related materials were therefore used to reconstruct exposure duration and location rather than relying solely on generic staff assumptions. For example, the declarations identify years of employment, the buildings in which teachers and staff worked, office locations, classrooms used, and time spent in other rooms or suites on campus. That type of individualized occupancy information is essential in a PCB school case because contaminant levels can vary sharply between buildings, floors, and room types. A teacher working for years in a contaminated office suite or shop area may have experienced materially different exposure than a staff member who rotated between buildings or spent less time in the highest-concentration spaces. By tying measured air and dust concentrations to individual work histories, RoseyFields converted environmental contamination data into person-specific dose and risk estimates rather than generic building-level conclusions.
The final analytical step was translating those exposure scenarios into quantitative risk estimates. The July 31, 2024 risk report included both noncancer hazard assessment and carcinogenic risk assessment, with specific sections addressing the PEET tool, hazard quotient calculations, cancer risk from indoor-air exposure, and cancer risk from dust exposure. The November 2024 supplemental materials indicate that portions of the dust-ingestion and cancer-risk calculations were updated, including a correction to the dust-ingestion absorption discussion, but that those revisions did not alter the overall risk conclusions. In particular, the supplemental materials explain that an error related to one plaintiff’s dust-ingestion hazard calculation was corrected without changing the resulting hazard quotient, and that minor corrections to cancer-risk estimates associated with dust ingestion similarly did not alter the overall conclusions.
The noncancer component of the analysis appears to have relied on hazard quotient methods consistent with ATSDR, EPA, and Vermont’s school-air framework. Vermont’s school guidance explicitly defines HQ as the ratio of estimated exposure to a level at which no adverse effects are expected and notes that an HQ of 1 or less is generally considered negligible risk. The supplemental materials likewise state that the hazard quotients for the plaintiffs exceeded 1. For carcinogenic risk, the analysis compared plaintiff-specific exposures to a de minimis cancer-risk target of 1 in 1,000,000, a common EPA benchmark used to identify potentially unacceptable excess cancer risk. By evaluating both inhalation and dust ingestion, and by applying these calculations to plaintiff-specific work histories rather than only to generic school occupancy assumptions, RoseyFields created a litigation-oriented risk assessment grounded in accepted environmental-health methods.
Results and Technical Findings
The first major finding was that Burlington High School contained widespread PCB contamination in building materials and indoor environmental media at levels well above Vermont’s school-air screening benchmark. The available environmental reports consistently indicate that PCB-containing materials were present throughout the school and that indoor-air concentrations exceeded Vermont’s 15 ng/m³ screening value in every building tested. Building F emerged as a particularly elevated area, with measured indoor-air concentrations in the thousands of nanograms per cubic meter—orders of magnitude above Vermont’s screening value and far above the action levels Vermont later established for older students and adults. These results strongly support the conclusion that the school did not present merely background-level PCB contamination, but rather a building-specific indoor source problem capable of materially increasing occupant exposure.
The second major finding was that the school environment supported multiple PCB exposure pathways, not just inhalation of indoor air. The case materials consistently describe a pathway in which PCBs emitted from caulk and other primary sources enter indoor air as vapors, then deposit to surfaces and accumulate in settled dust, creating an additional route of incidental ingestion and possibly dust inhalation. That pathway matters because school staff can spend years in offices, classrooms, prep rooms, and shared spaces where settled dust is repeatedly disturbed, especially in older buildings with persistent indoor contamination. By explicitly incorporating dust ingestion in addition to inhalation, RoseyFields’ analysis addressed the real behavior of semivolatile PCB contamination indoors rather than assuming that air concentrations alone fully capture exposure.
The third major finding was that plaintiff-specific exposure estimates supported elevated noncancer and cancer risk conclusions. The supplemental materials state that the plaintiffs’ hazard quotients exceeded 1 and that their cancer risks exceeded EPA’s de minimis risk level of one in one million. The same materials indicate that updates to one plaintiff’s work-history assumptions and corrections to certain dust-ingestion calculations did not change the overall opinions of the original July 31, 2024 risk report. In other words, even after refinement of the exposure assumptions and calculation details, the fundamental conclusion remained that the staff members assessed had experienced PCB exposures high enough to exceed accepted risk-management benchmarks. That is a significant result in a litigation setting because it shows that the risk conclusions were not an artifact of a single arithmetic error or a single overly conservative assumption; they persisted after correction and revision.
A fourth key finding was that school PCB risk assessment depends heavily on the interaction between building contamination, occupant behavior, and the choice of exposure framework. Vermont’s screening values, school action levels, and short-term occupancy guidance are not simple “bright line” cleanup thresholds; they are risk-management tools built around assumptions regarding age, exposure duration, background PCB sources, and acceptable hazard levels. RoseyFields’ work extended beyond those generic tools by incorporating plaintiff-specific building use and time-location patterns. This is exactly the kind of refinement that matters in school contamination litigation, because a teacher who worked for years in a highly contaminated wing or office may have experienced a materially different dose than a generic “adult staff” exposure scenario used in a state action-level calculation. The project therefore demonstrates the value of combining public-health screening frameworks with individualized forensic exposure reconstruction.
Conclusions
This project illustrates RoseyFields’ ability to conduct indoor environmental exposure reconstruction and chemical-specific risk assessment in complex building contamination cases. The Burlington High School PCB matter required more than identifying PCB-containing caulk or reporting elevated air concentrations. It required tracing the movement of PCBs from legacy building materials into indoor air and settled dust, evaluating how those contaminants created inhalation and ingestion exposures for school occupants, and translating school-wide contamination data into individualized estimates of hazard and cancer risk for identified staff members. By integrating building-source information, environmental sampling data, Vermont and EPA school-air benchmarks, and plaintiff-specific work histories, RoseyFields produced a technically grounded assessment of whether staff experienced harmful PCB exposure during their time in the school.
The project also demonstrates a broader capability that is highly relevant to school, residential, and commercial building cases involving semivolatile organic contaminants: the ability to move from environmental detection to human-health interpretation. In many indoor contamination disputes, the central question is not whether a contaminant was present somewhere in a building, but whether the concentrations and occupancy patterns were sufficient to create a meaningful risk to the people who used the space. Answering that question requires understanding emission from building materials, indoor partitioning and secondary-source behavior, exposure-route contributions, school- or building-specific toxicological benchmarks, and individualized time-location histories. RoseyFields’ PCB school case study shows how those elements can be combined into a defensible risk assessment suitable for expert support and litigation strategy.
Dr. Paul Rosenfeld led the technical risk assessment for this matter, applying environmental exposure analysis, toxicology, and regulatory risk-assessment methods to evaluate staff exposure to PCBs in the indoor school environment. His work integrated building-material source information, indoor air and dust sampling data, plaintiff-specific occupancy histories, and health-protective exposure benchmarks to assess both cancer and noncancer risks associated with long-term PCB exposure. The project reflects Dr. Rosenfeld’s broader expertise in indoor environmental contamination, human health risk assessment, and forensic evaluation of chemical exposures in schools and other occupied buildings.
References
Agency for Toxic Substances and Disease Registry (ATSDR). (2022). Calculating hazard quotients and cancer risk estimates.
Environmental Health & Engineering, Inc. (2024, February 29). Indoor environmental exposure assessment to PCBs at Burlington High School, 52 Institute Road, Burlington, Vermont.
Fuss & O’Neill, Inc. (2020, December 14). Indoor air sampling for polychlorinated biphenyls (PCBs): Burlington High School and Technical Center, Burlington, Vermont.
Vermont Department of Health. (2020, October). PCBs in indoor air of schools: Development of a screening value.
Vermont Department of Health. (2021, updated September 2023). PCBs in indoor air of schools: Development of school action levels.
Vermont Department of Health & Vermont Department of Environmental Conservation. (2022, revised January 2024). PCBs in indoor air of schools: Short-term occupancy options.