Highlights from the 32nd SNA Annual Meeting from a Human Health Risk Perspective
Betty Krupka, CDM
The theme of this year’s SETAC North America Annual Meeting was “Navigating Environmental Challenges: Historical Lessons Guiding Future Directions.” It was with an eye towards remembering the past while forging ahead to the future that the Human Health Risk Assessment Advisory Group (HHRA-AG) developed its platform sessions. Presenters at this year’s conference tackled issues as diverse as human health risks arising from pharmaceuticals in the environment, polycyclic aromatic hydrocarbon (PAH) exposure and its implications for human and ecological health, the risks of remediation versus the hypothetical risk to human and ecological health, and what lessons could be learned from the past to influence better risk communication in the future. Though the topics presented at this year’s conference discuss new issues pertaining to human health, speakers used the knowledge gleaned from the past to take on the issues risk assessors are facing in the 21st century.
The prevalence of pharmaceuticals and personal care products (PPCPs) in our environment drew a capacity crowd to the HHRA-AG’s first session, titled “Assessment of Human Health Risks Arising from Pharmaceuticals in the Environment.” The potential toxicity of these substances, as well as their resilience in the environment and low biodegradability led several speakers to underscore the importance of developing screening levels for more PPCPs. Few published values exist, giving credence to the need for additional research. The unfamiliarity of many of these substances to both risk assessors and regulatory bodies alike, as well as the uncertainties regarding fate and transport within the environment of these chemicals, make it difficult to properly assess their risk to human health. Also highlighted in the session was the need for an entirely different framework for characterizing risk from antibiotic-resistant pathogens. Antibiotic resistance is creating new and ever more dangerous pathogens. However, it is not any particular species that is the contaminant but the antibiotic resistance itself which is passed between species.
PAH exposure continued to be an important topic at this year’s conference, made more prominent by the anticipated release of the final version of the position paper Development of Relative Potency Factor (RPF) Approach for PAH Mixtures by the U.S. Environment Protection Agency (EPA) later this year. Currently EPA considers seven PAHs to be probable human carcinogens. This number is expected to increase to 24 based on the latest external review draft released by the EPA in February of 2010. Speakers at Tuesday’s platform session on "PAH Exposure and Implications Regarding Human and Ecological Risks" indicated that EPA’s PAH RPF study will result in significantly higher cancer risks from PAHs and increased regulation of PAHs. PAH concentrations in the environment also continue to increase, presumably via new, unregulated sources. One source of particular concern is the use of coal tar-based sealants, which are ubiquitous in urban environments through their use on driveways and parking lots.
Speakers in Wednesday’s session, "Evaluating Human Health and Ecological Risk Assessments and Remediation Decisions: Is the Cure Worse than the Disease?" illustrated primarily through the use of case studies that erring on the side of a more stringent remedy is not necessarily the most protective decision for human health and the environment. In one example, a proposed lead remediation program was proved to be more harmful to human health than the theoretical risk from lead itself, and did not consider an array of potential risks from the proposed cure. Other speakers illustrated that the potential damage to sensitive environments may outweigh the minimal gains in protection of human health. Remediation cannot blindly be prescribed as the remedy for every situation where a risk has been identified. The potential for a greater risk than the initial risk from contamination must be considered when evaluating potential treatment. As risk assessors we have a responsibility to do no further harm.
A logical conclusion to the HHRA-AG platform series, Thursday’s presentations discussed issues of communicating risk, which can be complex when the public and other key stakeholders are involved. Perception of risk is often complicated by issues of community stress, fear, and loss of property and livelihood. While it is important to keep the public informed, and to use dissemination of risk information to shape the public dialogue and formation of public policy, it must be done carefully so that all parties remain informed and so as not to create any unnecessary panic.
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