Field data and numerical modeling: A multiple lines of evidence approach for assessing vapor intrusion exposure risks.

USEPA recommends a multiple lines of evidence approach to make informed decisions at vapor intrusion sites because the vapor intrusion pathway is notoriously difficult to characterize. Our study uses this approach by incorporating groundwater, soil gas, indoor air field measurements and numerical models to evaluate vapor intrusion exposure risks in a Metro-Boston neighborhood known to exhibit lower than anticipated indoor air concentrations based on groundwater concentrations. We collected and evaluated five rounds of field sampling data over the period of one year. Field data results show a steep gradient in soil gas concentrations near the groundwater surface; however as the depth decreases, soil gas concentration gradients also decrease. Together, the field data and the numerical model results suggest that a subsurface feature is limiting vapor transport into indoor air spaces at the study site and that groundwater concentrations are not appropriate indicators of vapor intrusion exposure risks in this neighborhood. This research also reveals the importance of including relevant physical models when evaluating vapor intrusion exposure risks using the multiple lines of evidence approach. Overall, the findings provide insight about how the multiple lines of evidence approach can be used to inform decisions by using field data collected using regulatory-relevant sampling techniques, and a well-established 3-D vapor intrusion model.

Ipilimumab and whole brain radiation therapy for melanoma brain metastases.

Brain metastases (BM) frequently develop in patients with melanoma and are associated with a poor prognosis. Whole brain radiation therapy (WBRT) is a standard intervention for intracranial disease, particularly in patients with multiple BM. Ipilimumab improves survival in patients with advanced melanoma. The purpose of this study is to investigate the safety and efficacy of concurrent WBRT and ipilimumab. A retrospective analysis was conducted of 13 consecutive patients treated with WBRT within 30 days of ipilimumab administration. Radiographic response, as measured by serial magnetic resonance imaging scans post-treatment, was graded by modified World Health Organization (mWHO) and immune-related response criteria (irRC) in the 9 patients with follow-up imaging. Treatment-related toxicity was prospectively assessed during treatment. Four of nine patients (44 %) experienced partial response or stable central nervous system (CNS) disease as measured by mWHO criteria. This number increased to 5 patients (56 %) when irRC criteria were used. Rates of treatment-related neurologic toxicity were low with only one patient experiencing grade 3-4 neurologic toxicity. There was a high rate of intratumoral hemorrhage in this patient population, with 10 of 10 patients with post-treatment imaging demonstrating new or increased intratumoral bleeding after WBRT. This retrospective study demonstrates that the primary pattern of CNS response to WBRT and ipilimumab is stable disease and not regression of BM. Furthermore, while the combination of WBRT and ipilimumab may offer promising efficacy, prospective studies are needed to further assess efficacy and toxicity.

Sewer Gas: An Indoor Air Source of PCE to Consider During Vapor Intrusion Investigations.

The United States Environmental Protection Agency (USEPA) is finalizing its vapor intrusion guidelines. One of the important issues related to vapor intrusion is background concentrations of volatile organic chemicals (VOCs) in indoor air, typically attributed to consumer products and building materials. Background concentrations can exist even in the absence of vapor intrusion and are an important consideration when conducting site assessments. In addition, the development of accurate conceptual models that depict pathways for vapor entry into buildings is important during vapor intrusion site assessments. Sewer gas, either as a contributor to background concentrations or as part of the site conceptual model, is not routinely evaluated during vapor intrusion site assessments. The research described herein identifies an instance where vapors emanating directly from a sanitary sewer pipe within a residence were determined to be a source of tetrachloroethylene (PCE) detected in indoor air. Concentrations of PCE in the bathroom range from 2.1 to 190 ug/m3 and exceed typical indoor air concentrations by orders of magnitude resulting in human health risk classified as an "Imminent Hazard" condition. The results suggest that infiltration of sewer gas resulted in PCE concentrations in indoor air that were nearly two-orders of magnitude higher as compared to when infiltration of sewer gas was not known to be occurring. This previously understudied pathway whereby sewers serve as sources of PCE (and potentially other VOC) vapors is highlighted. Implications for vapor intrusion investigations are also discussed.