AsbestosAsbestos Gasket Material in Muffler Systems of Vintage Cars For decades, asbestos-containing gaskets were used in virtually every system that involved fluid or gas transport; the temperature resistance and easy workability of these products made them ideally suited for the task. Their use extended to automobile exhaust systems, where, prior to the mid-1970s, asbestos gaskets were used at flange connections, or at the engine manifold. Sometimes asbestos paper was used inside the exhaust muffler.
ChemRisk
® was asked to evaluate exposure to asbestos as a result of repairing and maintaining exhaust systems containing these types of gaskets and mufflers. Sixteen pre-1974 model cars with old or original exhaust systems were assembled for the study. Air samples were analyzed by NIOSH Polar Contrast Microscopy and Transmission Electron Microscopy (TEM) methods, and bulk samples were analyzed by Polarized Light Microscopy (PLM) and X-ray Diffraction (XRD).
One hundred and seventy air samples were collected to determine worker, bystander, and background concentrations of asbestos due to repair work on these exhaust systems. The 8 hour time-weighted average (TWA) concentrations of airborne asbestos for workers who replaced two to four exhaust systems per day was estimated to be from 0.006 to 0.01 fibers/cubic centimeter, which is well below the current primary exposure limit (PEL) of 0.1 fibers/cubic centimeter.
BenzeneRisk Assessment Comparison: Two Dioxin Contaminated Sites ChemRisk
® performed a screening-level comparative risk assessment for two remedial alternatives for a former pesticide manufacturing Superfund site with dioxin-contaminated soils in northern New Jersey. The comparative risk assessment presented the physical and chemical risks associated with two remedial alternatives: the currently approved remedy, involving onsite containment of contaminated soil and material, and a hypothetical remedy, involving the removal of site soil and incineration in an offsite incinerator in Kansas.
The USEPA Region 2 had been re-evaluating the approved remedy presented in the Record of Decision for this Superfund site because of public pressure. The comparative risk assessment showed that the chemical risks to populations in New Jersey due to soil excavation, and to populations in Kansas due to incineration, were one order of magnitude greater than those associated with onsite containment.
In addition, calculating physical hazards showed that the risk of at least one job-related fatality during remedy implementation was more than one order of magnitude higher for the excavation/incineration remedy versus onsite containment. The physical hazard assessment showed that the risk of an accident or fatality while contaminated materials were being transported for excavation/incineration remedy was three orders of magnitude higher than the onsite containment remedy. The USEPA Region 2 subsequently gave full approval to the onsite containment remedy.
Dioxins, Furans and PCB'sDioxins-Midland, Michigan – Dow ChemicalDioxin contaminated soil has been a significant public health concern since 1980. Dioxins are some of the most highly researched family of environmental contaminants; the scientific community has been highly interested in dioxins because of their high acute toxicity, carcinogenicity and environmental persistence.
ChemRisk
® performed a comprehensive Monte Carlo-based risk assessment of the historical deposition of dioxins and furans surrounding a former incinerator at the Dow facility in Midland, focusing on contaminated residential soil, river sediment, and floodplain soils in northern Michigan. For this analysis, a probabilistic risk assessment was used to establish a site-specific soil criterion. ChemRisk
®also provided advice on how to assess the human and ecological hazards associated with the presence of these chemicals in flood plains downstream of the incinerator. The soil concentrations were in the range of 50-400 ppt of toxic equivalents (TEQ).
As part of this assessment, an in vitro bioaccessibility study was conducted to determine the fraction of dioxins and furans that may dissolve in the gastrointestinal tract of humans, and clean-up levels were thus derived. The study’s results have been published in the scientific literature and presented at several scientific conferences. Further work is currently being performed to determine the bioavailable fraction from site soils through feeding studies using rats and miniature swine. Other aspects of this project include community outreach programs, regulatory meetings.
Indoor DustEvaluation of Impacts to a Building in Lower Manhattan Following Collapse of WTC on 9-11-01ChemRisk
® was retained by an insurance company to assist in understanding the environmental impacts of the collapse of the WTC towers on a building located in lower Manhattan, NY. This project was conducted as part of litigation brought by the building owner against the insurance company. The claim was predicated on the assumption that WTC dust had entered the building and impacted the building to such a degree that the owner needed to conduct a gut rehabilitation of the building. The project involved analyzing more than 25,000 environmental samples with an associated 100,000 chemical analyses. The ChemRisk
® team performed extensive QA/QC of the raw data and created a database to manage the data; the data was then analyzed to determine environmental impacts by floor and building area. An assessment of human health risks under a variety of scenarios was conducted to determine how to renovate the building and return it to use.
Part of the analysis also involved determining exactly where WTC dust had impacted the building structure. To undertake this task, ChemRisk
® investigated various WTC dust signatures proposed in the scientific community; however, because of the controversy surrounding the proposed signatures, ChemRisk
® developed an independent WTC dust signature.
PFOAPerfluorooctanoic acid (PFOA), a synthetic chemical, is essential in fluoropolymer processing. Recent concerns have arisen due to considerable scientific uncertainty regarding the route(s) of exposure, the potential risks of exposure, and evidence of low level exposure to the general U.S. population.
ChemRisk
® was asked to conduct a historical exposure reconstruction for residents in Ohio and West Virginia exposed to perfluorooctanoic acid (PFOA) from releases from a DuPont fluoropolymer manufacturing facility that had operated in the area for 53 years. PFOA exposures to workers in the facility were also evaluated. This project was conducted as part of litigation resulting from a class action lawsuit by plaintiffs requesting medical monitoring for those in the class. The retrospective exposure analysis required estimating historical releases to the environment using a mass balance approach, followed by quantifying PFOA in various environmental media using air dispersion, soil, groundwater and surface water models.
Radiological ExposuresRadiological Illness Compensation (ORAU)ChemRisk
® was retained to determine radiological exposures at Sandia National Laboratory. Claims have been filed under the Energy Employees Occupational Illness Compensation Program Act (EEOICPA), which allows claims to be filed by workers at plants or at places that supported atomic weapons plants. The technical basis documents for thousands of claims were reviewed to support NIOSH analysis.
The results of the literature search were used as raw data for a probability of causation program that determined which of the cases were likely the result of exposure at the labs. A probability of causation of greater than 50% resulted in the acceptance of a claim and subsequent payout to the claimant.