Variations of radon and airborne particulate matter near three large phosphogypsum stacks in Florida.

Approximately 1 billion tons of phosphogypsum (PG), a by-product of the fertilizer industry, are currently stacked in Florida. PG emits radon gas, which is a risk factor for lung cancer and can also increase particulate matter (PM) associated non-cancer mortality in exposed individuals. We measured concentrations of atmospheric radon and particulate matter near PG stacks and their short-term variations at different distances to estimate exposures in nearby communities. Specifically, we measured atmospheric levels of radon, and mass concentrations of PM1, PM2.5, and PM10, and number concentrations of PM0.3, PM0.5, PM1, PM2.5, PM5, and PM10 near three large PG stacks in Florida. Atmospheric radon was collected at distances of 2.5, 5.0, and 7.5 miles downwind from three large PG stacks using charcoal-based kits and measured by liquid scintillation counting. A professional radon monitor was used to take 24-h-average radon reading at 5.0 miles from each stack for comparison purposes. The median (IQR) radon levels were 0.325 (0.150, 0.675), 0.150 (0.150, 0.650), and 0.500 (0.150, 0.700) pCi/L at 2.5, 5, and 7.5 miles, respectively. The median (IQR) PM2.5 levels were 5 (4, 6), 5 (3, 7), and 5 (2, 9) µg/m3 at 2.5, 5, and 7.5 miles, respectively. Non-parametric Kruskal-Wallis test could not detect any association between radon or PM levels and distances (2.5-7 miles) from PG stacks. With scintillation counting, median radon levels detected were above the US Environmental Protection Agency (EPA) recommended standard in some of the sites; however, much higher levels were detected through the more advanced digital monitor. PM2.5 levels were below the US-EPA 24-h average national ambient air quality standard in the study area. We conclude that ambient radon levels near PG stacks could exceed US EPA recommended outdoor standards and do not vary within a short distance from the sources, implying similar exposures in nearby communities.

Immediate increase of plasma protein complement C3 in response to an acute stressor.

Whereas chronic stress has immunosuppressive effects, the more immediate immunologic consequences of acute stressors are less known. We postulated that, as part of their 'fight or flight' response, rainbow trout would rapidly increase the efficacy of their natural immune system by means of increased concentrations of crucial plasma proteins. Plasma samples were taken from resting fish and from fish 5, 10 or 20 min after initiation of a stressful regime. Using crossed immunoelectrophoresis, we documented increases in concentrations of complement C3 and 3 other proteins within 5 min of initiation of stress. The concentration of C3 nearly doubled within 10 min of initiation of stress and had returned to near resting level by 20 min. This rapid kinetics preclude dependence on gene activation, the basis of the acute phase response. Potentiation of natural immunity, which can reasonably be expected to be selectively advantageous during or immediately after acute stressors may be one result of this increase.