The mercury arc lamp has long been used as a light source for fluorescence microscopy. Almost every new research or clinical grade fluorescence microscope is equipped with a mercury arc lamp. However, mercury arc lamps are hazardous, consume a lot of energy, have a high cost of ownership and are unreliable. Metal halide doped mercury arc lamps have become widely employed because they address the reliability concerns around traditional mercury bulbs, increasing bulb longevity ten times. However the cost of a metal halide bulb is typically about five times that of a mercury bulb of equivalent radiant power, offsetting much of the potential savings in bulb replacement costs. Ozone-free Xenon sources have no mercury, reducing the amount of hazardous waste, but they perform at a lower intensity. Solid-state technologies like LED illumination have the potential to solve all the concerns associated with the use of mercury, but LEDs alone have yet to achieve the brightness needed for microscopy. Thus, the use of mercury lamps has remained a necessary and wide-spread source of mercury in research laboratories for decades. Lumencor has overcome the frustration associated with this dependence on mercury and has revolutionized the solid-state technology world by manufacturing Light Engines capable of replicating and exceeding the spectral properties of the mercury arc lamp. In so doing, Lumencor has obviated the toxic disadvantages previously associated with microscopy. Light Engines allow scientists to utilize high-performance, solid-state, sustainable lighting solutions in clean, safe laboratories using mercury free microscopes.
Mercury-free is the Way To Be
One of the most compelling attributes of Lumencor light engines is that they are entirely mercury free. Here we examine why eliminating mercury is a worthwhile goal, and one that is shared by organizations worldwide. Reasons for eliminating mercury fall into two groups:
- Health and Environmental
- Economic and Logistical
Economic and logistical considerations are laid out on our website (Low Cost of Ownership, Lower Power Consumption). Health and environmental considerations are harder to quantify, because mercury exists in different forms (elemental mercury liquid, elemental mercury vapor, mercuric ions and organomercurials) with different toxic effects.
For example, a mercury fever thermometer contains about 500 mg of mercury, whereas a single mercury (HBO) or metal halide bulb used for fluorescence microscopy contains about 20 mg. However the mercury in the thermometer is largely liquid, which is not particularly toxic itself, but is dangerous to the extent that it is a source of mercury vapor. The mercury in a lamp bulb is pressurized vapor. Mercury vapor is particularly dangerous because it is readily absorbed through the lungs and mucous membranes. Once absorbed, it lingers. The half-life of mercury vapor in the human body is estimated to be 35-90 days. The primary target organ for inhaled mercury vapor is the brain. Here, it interferes with neurite elongation, a process that is central to neurological function. A video produced by researchers at the University of Calgary demonstrates this effect: