Mercury is the Roman name for the Greek god Hermes, the protector of travelers, thieves and merchants. On the periodic table of elements, the chemical symbol for mercury is Hg, from the Latin word - Hydrargyrum - meaning liquid silver. For some time it has been known that high concentrations of mercury can be toxic to humans, and steps have been taken to limit emissions to the atmosphere as mercury can migrate between air, soil and water and hence enter the food chain.

Some mercury compounds are more easily absorbed by living organisms than elemental mercury itself. When atmospheric mercury falls to earth, it may be altered by bacterial or chemical action into an organic form known as methylmercury which is more toxic than the original elemental mercury.

Mercury has been used in medicine, science and technology for many years. In addition to industrial releases, mercury can be found in thermometers, sphygmomanometers, dental fillings, fluorescent light bulbs, and other consumer products. It is thought this has lead to an increase in the amount of mercury found in the environment.

As a result, in October 2007 the European Commission launched a study of the current uses of mercury and mercury-free alternatives, including an assessment of mercury already circulating in society with products and waste.

The aim of the study is to provide an improved and updated overview of the mercury situation in the European Union and two of its trade partners, Norway and Switzerland. The European Commission has already adopted a strategy to reduce mercury levels in the environment and thereby reduce human exposure, and the current study is designed to improve the knowledge database by consultation. Two consulting companies have been engaged in this process.

Sphygmomanometers

The first sphygmomanometers (blood pressure measuring devices) were made as mercury in glass manometers, and generally are quite similar even today. The accuracy of the gauge, and the reliability of the device has meant it has survived in clinical use for over 100 years.
The fact that blood pressure is still measured in units of millimeters of mercury shows how entrenched this unit is in clinical practice. The World Health Organization has permitted its continuing use at a time when the SI units have displaced other traditional units from quantitative measurement.

The millimeter of mercury remains, but what about the mercury sphygmomanometer?

The lack of a clear successor to mercury lay in the question of accuracy. Alternatives did exist, these being the aneroid and the automated devices. Aneroid devices are mechanical and can suffer from being knocked out of calibration. Automated devices are still far from perfect, as is illustrated by the main validation protocol which will accept devices that are in error by more than 10 mmHg in up to 25 percent of patients at a time when clinicians are asked to measure blood pressure to within 2 mmHg. Further, the joint publication from the European Society of Cardiology, European Society of Hypertension and European Atherosclerosis Society recommends that automated devices are not to be used when deciding clinical treatment.

A solution to the problem has arrived, the Accoson greenlight 300. (www.greenlight300.com)

The traditional mercury display has been replaced by a series of bright green LEDs clearly displaying pressure in steps of 2 mmHg, and for the first time the clinically important cuff pressure deflation rate is indicated.?Most importantly the device self-calibrates to zero each time it is switched on, thus ensuring reliable accuracy and mimicking the comfort factor clinicians have been used to when a mercury column is on zero before taking a blood pressure measurement. The device has been validated to the new International Protocol of the European Society of Hypertension?by the Mayo clinic in the USA.

The strength of the greenlight 300 is that it is suitable for any patient group (including the pregnant and the elderly) where mercury was used in the past. This means clinicians can continue to measure blood pressure using the preferred manual auscultation method.

The greenlight 300 model has been developed to provide a reliable and accurate alternative to the mercury sphygmomanometer, and is now the recommended manual device of the British Hypertension Society (www.bhsoc.org)

The Accoson greenlight 300 is available through Adventa Health for certain selected countries.