The importance of problem formulations in risk assessment: A case study involving dioxin-contaminated soil

AbstractThe need to remediate contaminated soils is typically accomplished by applying standard risk assessment methods followed by risk management to select remedial options. These human health risk assessments (HHRAs) have been largely conducted in a formulaic manner that relies heavily on standard deterministic exposure, toxicity assumptions and fixed mathematical formulas. The HHRA approach, with its traditional formulaic practice, does not take advantage of problem formulation in the same manner as is done in ecological risk assessment, and historically, has generally failed to emphasize incorporation of site-specific information. In response to these challenges, the National Academy of Sciences recently made several recommendations regarding the conduct of HHRAs, one of which was to begin all such assessments with problem formulation. These recommendations have since been extended to dose response assessment. In accordance with these recommendations, a group of experts presented and discussed findings that highlighted the importance and impact of including problem formulation when determining the need for remediation of dioxin contamination in soils, focusing in particular on exposure assessment is described

A case study of potential human health impacts from petroleum coke transfer facilities

<p>Petroleum coke or “petcoke” is a solid material created during petroleum refinement and is distributed via transfer facilities that may be located in densely populated areas. The health impacts from petcoke exposure to residents living in proximity to such facilities were evaluated for a petcoke transfer facilities located in Chicago, Illinois. Site-specific, margin of safety (MOS) and margin of exposure (MOE) analyses were conducted using estimated airborne and dermal exposures. The exposure assessment was based on a combined measurement and modeling program that included multiyear on-site air monitoring, air dispersion modeling, and analyses of soil and surfaces in residential areas adjacent to two petcoke transfer facilities located in industrial areas. Airborne particulate matter less than 10 microns (PM₁₀) were used as a marker for petcoke. Based on daily fence line monitoring, the average daily PM₁₀ concentration at the KCBX Terminals measured on-site was 32 μg/m³, with 89% of 24-hr average PM₁₀ concentrations below 50 μg/m³ and 99% below 100 μg/m³. A dispersion model estimated that the emission sources at the KCBX Terminals produced peak PM₁₀ levels attributed to the petcoke facility at the most highly impacted residence of 11 μg/m³ on an annual average basis and 54 μg/m³ on 24-hr average basis. Chemical indicators of petcoke in soil and surface samples collected from residential neighborhoods adjacent to the facilities were equivalent to levels in corresponding samples collected at reference locations elsewhere in Chicago, a finding that is consistent with limited potential for off-site exposure indicated by the fence line monitoring and air dispersion modeling. The MOE based upon dispersion model estimates ranged from 800 to 900 for potential inhalation, the primary route of concern for particulate matter. This indicates a low likelihood of adverse health effects in the surrounding community. <i>Implications</i>: Handling of petroleum coke at bulk material transfer facilities has been identified as a concern for the public health of surrounding populations. The current assessment, based on measurements and modeling of two facilities located in a densely populated urban area, indicates that petcoke transport and accumulation in off-site locations is minimal. In addition, estimated human exposures, if any, are well below levels that could be anticipated to produce adverse health effects in the general population.</p

Guidelines for the communication of Biomonitoring Equivalents: report from the Biomonitoring Equivalents Expert Workshop

Biomonitoring Equivalents (BEs) are screening tools for interpreting biomonitoring data. However, the development of BEs brings to the public a relatively novel concept in the field of health risk assessment and presents new challenges for environmental risk communication. This paper provides guidance on methods for conveying information to the general public, the health care community, regulators and other interested parties regarding how chemical-specific BEs are derived, what they mean in terms of health, and the challenges and questions related to interpretation and communication of biomonitoring data. Key communication issues include: (i) developing a definition of the BE that accurately captures the BE concept in lay terms, (ii) how to compare population biomonitoring data to BEs, (iii) interpreting biomonitoring data that exceed BEs for a specific chemical, (iv) how to best describe the confidence in chemical-specific BEs, and (v) key requirements for effective communication with health care professionals. While the risk communication literature specific to biomonitoring is sparse, many of the concepts developed for traditional risk assessments apply, including transparency and discussions of confidence and uncertainty. Communication of BEs will require outreach, education, and development of communication materials specific to several audiences including the lay public and health care providers