Continuous measurements of outdoor 222Rn concentrations for three years at one location in Colorado

Measurements were made of 222Rn concentrations outdoors in Ft. Collins, Colorado, using a continuously sampling scintillation flask between January 1993 and December 1995. These data were analyzed for hourly, daily, and seasonal variations. The average 222Rn concentration at 1 m above the ground was 18 +/- 10 Bq m(-3) with a geometric mean of 15 Bq m(-3) and a geometric standard deviation of 1.7. Hourly averaged data indicated a diurnal pattern with the outdoor 222Rn concentration reaching a maximum in the early morning between 4:00 a.m. and 6:00 a.m. and a broad minimum between 1:00 p.m. and 4:00 p.m. in the afternoon. An analysis also indicated that the outdoor 222Rn concentrations were consistently lowest during the spring (March and April) and highest during the late summer (July-September).     

Hormesis: implications for cancer risk assessment

Current guidelines for cancer risk assessment emphasize a toxicant's "mode of action", rather than its empirically derived dose-response relationship, for determining whether linear low-dose extrapolation is appropriate. Thus, for reasons of policy, demonstration of hormesis is generally insufficient to justify a non-linear approach, although it may provide important insights into the actions of toxicants. We evaluated dose-response characteristics of four carcinogens reported to have hormetic dose-response curves: cadmium chloride; ionizing radiation; PAHs; and, 2,3,7,8-TCDD. For each, the study that documented hormesis in one organ also provided evidence of non-hormetic dose-responses in other organs or non-hormetic responses for seemingly similar carcinogens in the same species and organs. Such inconsistency suggests toxicologic reasons that the finding of hormesis alone is not sufficient to justify use of non-linear low-dose extrapolations. Moreover, available data in those examples are not sufficient to know whether hormesis is a property of the toxicants, the target organ, or the exposed species. From the perspectives of cancer risk assessment, the greatest informational value of hormesis may be that it provokes mechanistic studies intended to explain why hormesis occurs.     

Who is Hispanic? Implications for epidemiologic research in the United States

The most recent U.S. Census reported that Hispanics are now the nation's largest minority group. At the same time, increasing attention has focused on the inherent heterogeneity of the U.S. Hispanic population. Such a rapidly growing but heterogeneous minority poses potential challenges to population-based research. To understand those challenges better, we first considered the history of the demographers' question: "Who is Hispanic?" We then considered the implications of differing Hispanic identity criteria for disease surveillance. Although relevant to political and socioeconomic considerations, the Hispanic ethnic category may not be specifically useful for understanding most disease processes. For epidemiologic studies, there is need for more transparent criteria to classify subpopulations. Those criteria must be regularly subjected to analysis and validation.     

Comparison of NIOSH 5040 method versus Aethalometer to monitor diesel particulate in school buses and at work sites

This study, undertaken initially to understand apparent differences between two recent reports of diesel particulate matter (DPM) inside school buses, involved side-by-side comparisons of two different methods for measuring ambient and occupational exposures to DPM. The NIOSH 5040 method yields time-weighted-average measurements of elemental carbon (EC) and organic carbon (OC), whereas the Aethalometer yields near-real time measures of carbonaceous particles (black carbon or BC) by optical absorption. The two methods were compared on three school buses and in three different work sites. Three side-by-side sampling configurations were used (open-faced filter with and without two different cyclones) in triplicate along with two or three Aethalometers. BC readings were correlated with results from open-faced cassettes, but there were statistically significant differences between the results of side-by-side Aethalometers. In addition, Aethalometer airflow rates were inaccurate, the instruments were sensitive to vibration, optical calibration could not be performed, and historically derived conversion factors to relate EC and BC were not appropriate. The Aethalometer could prove useful for monitoring of industrial work sites, but only after a method for external calibration and improvements in pump design and vibration isolation are developed.     

Phosgene exposure: mechanisms of injury and treatment strategies

Phosgene (carbonyl chloride, CAS 75-44-5) is a highly reactive gas of historical interest and current industrial importance. Phosgene has also proved to be a useful model for the study of those biochemical mechanisms that lead to permeability-type pulmonary edema (adult respiratory distress syndrome). In turn, the study of phosgene-induced adult respiratory distress syndrome has provided insights leading to revised treatment strategies for exposure victims. We summarized recent findings on the mechanisms of phosgene-induced pulmonary edema and their implications for victim management. In light of that research, we also provide a comprehensive approach to the management and treatment of phosgene exposure victims.     

Unique presentation of blastic plasmacytoid dendritic cell neoplasm: a single‐center experience and literature review

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and highly aggressive hematological malignancy derived from precursors of plasmacytoid dendritic cells. Very few cases of BPDCN have been described with lack of skin manifestations at the time of diagnosis. Here we report two rare non‐cutaneous presentations of BPDCN without obvious skin lesions at our institution and also the literature review. Our first patient had a unique presentation of BPDCN confined to the sinonasal region with central nervous system involvement. The second patient we report is also atypical with regard to widespread disease that uncharacteristically spared the skin and bone marrow. BPDCN is a rare hematological malignancy involving immature plasmacytoid dendritic cells. It poses a diagnostic challenge requiring multidisciplinary approach to manage this disease. It is important to identify effective therapies for both cutaneous and non‐cutaneous presentations of BPDCN, since most cases are uniformly fatal with conventional chemotherapy alone. High‐dose induction therapy based on acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL) regimens, to achieve complete remission followed by allo‐hematopoietic stem cell transplantation from related or unrelated donors is recommended to improve long‐term survival in these patients. Larger scale studies are warranted to understand the pathophysiology of the disease and the important prognostic indicators for optimal management. Copyright © 2014 John Wiley & Sons, Ltd.