News Archive
Dr. Dennis J. Paustenbach and Dr. Robert D. Gibbons recently published an article titled "Radiological Risk Assessment of the Hunters Point Naval Shipyard (HPNS)" in the peer-reviewed journal Critical Reviews in Toxicology. The article is the first comprehensive evaluation of past, present, and future health risks associated with radionuclides at the site to be conducted in accordance with federal guidance.
The HPNS site has been of concern to the surrounding community for decades. The citizens have focused on the history of radiological research at the site and have come to believe that there were potential health hazards due to radioactive contamination. The authors hoped that the risk assessment would be helpful for characterizing the site for all the various stakeholders.
The analysis relies on more than 19,000 air and 50,000 soil samples collected during characterization and remediation efforts at HPNS between 1992 and 2017. Sophisticated statistical analysis of the highly censored datasets and RESRAD-ONSITE modeling software were utilized to estimate the risks to on-site residents and workers, as well as off-site residents in nearby neighborhoods. Interestingly, it was found that the pre-remediation theoretical incremental lifetime cancer morbidity risks for any on-site residents and on-site workers due to radionuclide contamination were found to be 3.2x10-6 and 1.3x10-6, respectively. The post-remediation risks to future on-site residents were found to be 6.3x10-8 (without durable cover) and 3.7x10-8 (with durable cover), while post-remediation risks to on-site workers were found to be 2.6x10-8 (without durable cover) and 1.6x10-8 (with durable cover).
Risk estimates for all scenarios were significantly below the acceptable risk threshold of 3x10-4 identified by various regulatory agencies. It follows that there is not, nor has there ever been, an unacceptable cancer risk from radiation to on-site workers or residents on- or off-site from soil or airborne dust associated with activities prior to, during, or after remediation activities. The authors acknowledged that some targeted remediation of certain aspects of the site were justified and accomplished several years ago.
The authors observed that if such low remedial goals had not been established, and had proper background sampling been conducted, prior to remedial action, remediation of most of the surface soils would not have been necessary to protect human health. This emphasizes the importance of establishing clear and scientifically rigorous soil remedial goals at sites, as well as understanding local radionuclide background concentrations prior to conducting remediation efforts.
The full article is open access and can be found on the Taylor & Francis Online website.
