Mercury is used in many measuring devices mainly in hospitals, clinics and doctors’ offices but also for in other measuring and control equipment.
Mercury is contained in many common medical measuring devices: sphygmomanometers (blood pressure devices), thermometers (specifically body temperature thermometers but also others) and a number of gastro-intestinal devices, such as cantor tubes, esophageal dilators (bougie tubes), feeding tubes and Miller Abbott tubes.
As in other types of instruments, mercury has traditionally been used in these devices because of its unique physical properties, including the ability to provide highly precise measurements. These instruments include barometers, manometers, but also porosimeters, pycnometers, hygrometers, tensiometers, gyrocompasses, mercury-containing reference electrodes, hanging drop mercury electrodes, gas flow meters, and coulter counters among others.
Relevant legislation and NGO policy work
In the EU - the European Commission included an action (Action 7) in view of restricting the marketing for consumer use and healthcare of nonelectrical or electronic measuring and control equipment containing mercury, in the 2005 EU Strategy on Mercury.
Directive 2007/51/EC, was published on 2 October 2007 in the Official Journal of the European Union.
The NGO activities and follow up of this issue are presented here in chronological order :
In October 2009, Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) published their Opinion on: Mercury Sphygmomanometers in Healthcare and the Feasibility of Alternatives (380KB)
Beyond the above restriction, the EC prepared a report with all relevant elements concerning potential restrictions in the use of mercury in measuring devices for professional use and in healthcare (e.g. sphygmomanometers in hospitals/clinics, porosimeters etc) which was sent this to the European Chemicals Agency (ECHA). The EC requested ECHA to evaluate the report and prepare, if appropriate, an Annex XV Dossier as foreseen by Article 69 of REACH. Subsequently, further discussion and consultation with the stakeholders will be carried out by appropriate means by ECHA when preparing Annex XV restriction report. ECHA will make the finalised Annex XV report publicly available and invite all interested parties to submit comments and contributions (see Art 69(6)). The Annex XV report is now available.; comments are due by 24 March 2011.
The Risk Assessment and Socio-economic Analysis Committees of ECHA (RAC, SEAC) will give their opinions on the suggested restriction taking into account comments submitted by the interested parties during the public consultation (see Art 70 and 71). [expected by March 2011]. Furthermore, interested parties will have a possibility to comment the draft opinion of SEAC. [expected summer-autumn 2011]
For more information, about the timetables and procedures, please, consult the new ECHA website at http://echa.europa.eu/reach/restriction_en.asp
Please see the EEB comments on the suggested restrictions on mercury use in measuring devices that was submitted during the public consultation that was concluded on the 24 March 2011. Additional comments on Phenymercury compounds were also submitted at the same time.
Furthermore, some individual countries have already taken action to ban or restrict the use of some or all products containing mercury such as Denmark, France, the Netherlands, Sweden, Norway. Canada and the UShave also taken similar steps
US: As of October 2, 2008, thirteen states have laws that limit the manufacture, sale and/or distribution of mercury fever thermometers: California, Connecticut, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, Rhode Island, Oregon, Washington. The Health Care Without Harm Web site presents information on specific state laws and municipal ordinances.
Information is also provided at http://www.epa.gov/hg/consumer.htm#bat bat and at http://www.newmoa.org/prevention/mercury/modelleg.cfm
Health Care Without Harm and the World Health Organization are co-leading a global initiative - Mercury Free Healthcare- to achieve virtual elimination of mercury-based thermometers and sphygmomanometers over the next decade and their substitution with accurate, economically viable alternatives. The initiative is a component of the UN Environment Programme's Mercury Products Partnership.
Information on the measuring devices
Mercury is used in certain thermometers, where a glass tube is filled with mercury and a standard temperature scale is marked on the tube. With changes in temperature, the mercury expands and contracts in a consistent manner and the temperature can be read from the scale. A mercury thermometer can be easily identified by the presence of a silver bulb. If the bulb is red, blue, purple, green or any other color, then it is not a mercury thermometer.
Mercury thermometers can be used to determine body temperature (fever thermometers), liquid temperature, and vapor temperature. Mercury thermometers are used to measure the temperature of liquids and vapors in households, laboratory experiments at educational and medical institutions, and industrial applications. Common household uses of mercury thermometers include fever thermometers and oven, candy and meat thermometers.
Mercury fever thermometers are made of glass the size of a straw, with a silvery-white liquid inside, and are a common item in many households, schools and medical facilities. There are two general types of mercury thermometers that measure body temperature:
Alternative Mercury-free Fever Thermometers that are reliable and accurate, are available in the market today. Alternatives that are most comparable in cost and use to the mercury fever thermometer include battery and solar powered digital thermometers. These can all be used orally, rectally, or in the armpit.
When choosing a battery powered digital thermometer, it is advisable to select one that contains a replaceable battery. The battery is a button cell battery and may contain a small amount of mercury, so it should be recycled through a local battery collection program or the existing household hazardous waste collection center.
Within the educational and medical sectors, mercury thermometers may be used in many applications, including chemical experiments, water and acid baths, blood banks, ovens and incubators
Industrial uses of mercury include: use in power plants and piping, chemical tanks and vats, heating and cooling equipment, breweries, canneries, bakeries, candy making, dairies, ships, wineries and distilleries, and paint kettles.
Thermometer cleanup and disposal:When a thermometer breaks during usage or if it is not properly disposed of, it will release mercury vapors that are harmful to human and ecological health. The US EPA website has information on what to do when a thermometer breaks or spills.
Many states and local agencies have developed collection/exchange programs for mercury-containing devices such as thermometers. Some counties and cities also have household hazardous waste collection programs.
A sphygmomanometer or blood pressure meter is a device used to measure blood pressure, comprising an inflatable cuff to restrict blood flow, and a mercury or mechanical manometer to measure the pressure. It is always used in conjunction with a means to determine at what pressure blood flow is just starting, and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope.
The mercury sphygmomanometer has long been considered the “gold standard” of blood pressure measurements because all medical personnel have been trained to use it, the blood pressure readings are fairly reliable, it is often (mistakenly) believed that the device never needs to be calibrated, and it can be used universally – including in special clinical conditions such as arrhythmia, pre-eclampsia and certain vascular diseases where
Other measuring devices
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries. Barometers use large quantities of mercury (around 999 g more than a fever thermometer). Any barometer breakage poses an enormous risk of contamination and severe health effects, not to mention significant clean up costs. Mercury free barometers, both aneroid and digital, are already available in the market, and can be transported without the need for hazardous packaging. Breakage of mercury barometers does not only happen in the manufacturers’ workshop, but can and do occur in schools, homes, and other buildings. These breakages can involve significant clean up costs (evacuation & closure of schools, hazardous waste clean up & disposal measures), risk of contamination into the environment through improper disposal, and risk of health effects (e.g. through direct inhalation).
Porosimetry is a major mercury user.The purpose of porosimeters is the measure of the porosity of a sample – that could be sintered filters, catalytic converters, fuel cells, bone replacement materials, ceramics, etc. The advantage of mercury is that it is a fast, reliable technique covering a wide range of pores from 0.003 ìm to 400 ìm. There are various alternatives, but none is ideal for certain substances and/or certain pore sizes. Further, as in the case of sphygmomanometers, there are certain validation standards that would also have to be revised in order to move away from mercury porosimetry. After testing, about 4% of mercury remains in a typical sample, the rest is recovered for re-use by the company that is doing the testing. That means that over a period of time, testing 25 samples, you use 100% of your quantity of mercury in the machine. The question is what happens to the mercury that remains in the samples. Industry assures us that it is possible to recycle 100%. Due to the fact that this process is normally done in research labs, one would hope that a high rate of recycling is carried out – but there is no information to confirm that. For the research that was done for the 2008 COWI/Concorde study for DG Environment, there was an estimation of 25-30% of recycling in addition to a certain amount of mercury in samples that goes to final disposal – for example in salt mines in Germany. However, there is little real data to back up these numbers.
Even though several measures have been taken to control the use and emissions of mercury in the EU, some uses of mercury still remain, such as its use in the following measuring devices used by industry and professionals: Barometers, manometers, sphygmomanometers and strain gauges used to measure pressure, and thermometers to measure temperature. Porosimeters, pycnometers and metering devices for determination of the softening point measure different parameters related to the structure and porosity of a sample. Mercury electrodes used with specific devices like polarographs, for instance to determine trace elements in the environment and in biological fluids.
Barometers, manometers, sphygmomanometers, strain gauges and thermometers contain mercury as an integral part of the device whereas metering devices for determination of the softening point, polarographs (using mercury electrodes), porosimeters and pycnometers use mercury during the measurement and need to be refilled regularly.
Mercury-free alternatives are already available and dominate the market for most of the measuring devices. The alternatives are often electronic devices or devices making use of other liquids such as alcohols for their functioning. For porosimeters and mercury electrodes used in voltammetry no technically feasible alternatives have been identified which would cover all application areas.
Polarography is an electrochemical analytical technique which is used in chemical labs, in universities, in industry. Mercury is used as a sensor electrode. Voltage is applied, and currents are measured to this sensor. It is mainly used to determine toxic traces and low concentrations of heavy metals such as lead, cadmium, chromium or mercury.The center of the whole device is a glass vessel and three electrodes immersing in this glass vessel, including the mercury sensor. The mercury electrode is a glass capillary, from which a small mercury drop is extruded. In the glass vessel the sample we want to analyze is introduced. At the end of the determination the mercury drop falls off to the bottom of the vessel and from there it can be collected at the end of the measurement. Filling of the electrode is typically 6 milliliters which is approximately 80g mercury. Under normal circumstances this will last for half a year to one year of every day use. Based on the consumption of mercury and estimated number of polarographs worldwide we assume that the total consumption is about 250 to 350kg worldwide. From a (mercury) life cycle perspective of the user, usually, the mercury is purchased from a supplier, it is used in a lab, collected in a close container and finally returned to a recycler.
High investments (purchase, running)
Problems with some sample matrices (e.g. sea water, pure chemicals)
Laboratory infrastructure required
Besides liquid mercury as a sensor there are other sensors existing, some of them are commercially available and some others are still in a research state. Typically they are based on carbon or on noble metals like gold or platinum. These sensors have quite severe restrictions – this is why most of them are only used in research fields and not in routine. If we look into industry we have nearly no users using such sensors because of the restrictions. Their advantages are that they can replace some mercury applications and they are sometimes even more sensitive than the mercury sensor.
However, the most important restriction is that they are not as robust as the mercury sensor, so when it comes to reliability the classic electrode is better. The alternative sensors need more maintenance, show more interferences, require more operator skills and sometimes the alternatives even contain toxic metals like mercury.