March 2006 

Get the Lead Mercury Out!! 

By Val Miller 

Regulatory Issues 

Devices containing mercury are used in many facets of our lives. Entire measurement and 

control systems have been developed around items that contain mercury in some form. 

From the mercury-wetted relay contacts in automobiles and instrumentation control 

circuits, to oral thermometers and blood pressure sphygmomanometers that have been 

essential components of our healthcare system, the use of mercury has maintained a vital 

place in our lives. Now, due to health and environmental hazards related to the use of 

mercury and its escape into the environment, efforts are being made through legislation to 

control and eliminate the use of devices containing mercury in the United States. 

In the 2003 NCWM State Laboratory Program Workload Survey, State laboratories were 

asked if their state had enacted legislation or rules restricting the use of mercurycontaining devices. Of the thirty respondents, only three answered that their state was 

working to restrict the use of mercury-containing devices. Today, a significant number of 

states have adopted, or are working on, legislation that will limit or prohibit the sale and 

use of devices containing mercury, though most current legislation has a provision to 

allow an exemption where replacement is not technically or economically feasible. These 

restrictions include mercury-in-glass thermometers. 

Background on Thermometry Standards 

Thermometers containing mercury are typically considered among the most accurate and 

stable temperature-measuring devices available for general temperature measurements. 

Because they are basically passive devices, they have been relatively inexpensive to 

purchase and their relatively long recalibration cycles make them a very economical 

means of accurate temperature measurement. The American Society for Testing and 

Materials (ASTM) has developed a documentary standard, ASTM E1, for the design, 

manufacture and testing of mercury-in-glass thermometers covering a temperature range 

of -80 °C to 405 °C (-112 °F to 766.4 °F). Many industries, including those regulated by 

USDA, FDA, API and U.S. Pharmacopeia, have developed testing methods, or use 

ASTM-developed methods, that are based on the use of ASTM E1 thermometers. In fact, 

a recent search of the ASTM standards database revealed that 839 other ASTM standards 

reference ASTM E1 in some form. 

Use of Mercury Thermometers 

On the surface, it would seem a simple matter to replace mercury thermometers with 

electronic devices, as thermocouple and resistance thermometry technology has 

developed to an accuracy level capable of meeting or exceeding that of mercury-in-glass 

thermometers. So what is the problem? 

 ASTM and other standards development bodies have developed testing processes based 

on the specific operating characteristics of the measuring devices specified in the 
documentary standard that describes a test. Because many of these testing processes have 

qualitative measurement results, the result is dependent on the laboratory’s ability to 

obtain repeatable measurements when using that process. The thermal component of the 

process can be very critical to the measurement result. Each style of thermometer has a 

different response to temperature change, with some responding more quickly than 

others. Because the process depends on the device response, users of these testing 

processes cannot deviate from the use of the specified measuring device without risking 

the validity of their measurements. After making a change to the procedure such as 

would be required for mercury-free thermometers, validation of the process and 

accreditation of the laboratory’s measurement results may take years. 

Some, but not all, testing processes have already been developed and validated allowing 

the use of both mercury-in-glass thermometers as well as other types of thermometers. 

For those processes, use of mercury-free thermometers is quite acceptable and the legal 

restrictions on the sale of mercury thermometers will simply mean that any mercury 

thermometers now in use will eventually be replaced with acceptable alternative 

thermometers and all will be well. However, if alternative thermometers have not been 

specified, there may be legal issues if a regulatory body like FDA requires a certain 

ASTM process that has not been validated using an alternative thermometer. If a testing 

laboratory reports that they used the required process, but used an alternative 

thermometer, the results may be deemed unreliable. For instance, a specified procedure 

requires, during the heating of a material, that a mixing process is started at 200 °C so 

that a specific reaction occurs, but this procedure has only been validated with mercuryin-glass thermometers. If the laboratory uses a bead thermistor to measure the 

temperature, there can be no certainty that the correct reaction took place because the 

bead thermistor has a different thermal response than the mercury-in-glass thermometer. 

Because the test procedure was not followed exactly, test results should not be reported 

stating that the specified procedure was followed. 

Increased costs will likely result from the restrictions on mercury thermometers. 

Currently, most equivalent electronic thermometers, having similar accuracy and 

readability, are more expensive to purchase than their mercury-containing counterpart. 

And, since they are no longer passive devices, more frequent calibration will be required 

adding to the cost of operations. One permissible reason to apply for an exemption to the 

ban on mercury-containing devices is increased costs, but no criteria for economical 

feasibility have been developed. What is affordable for one organization may not be for 

another. More work is required to better define economic feasibility. 

I recently participated in a teleconference call coordinated by Interstate Mercury 

Education & Reduction Clearinghouse (IMERC) to discuss an exemption application that 

was submitted to the State of Connecticut by a thermometer manufacturer for the sale of 

mercury-in-glass thermometers manufactured to ASTM Standard E1. Connecticut has 

enacted legislation prohibiting the sale of most devices containing mercury. Included in 

their legislation, however, is the possibility of obtaining an exemption when a technically 

or economically feasible substitute for a mercury thermometer is not available or a 

Federal health or safety requirement exists. During that conference call it quickly became 
apparent that there is a growing movement by state environmental departments to restrict 

or prohibit the sale of mercury-containing devices. This was demonstrated by what 

seemed to be the general consensus of the State participants that since there are other 

devices capable of measuring and controlling temperature, March 2006 Page 3 there 

should be no issues with using electronic devices or liquid-in-glass thermometers using 

liquids other than mercury in place of mercury-in-glass thermometers. As of this writing 

in mid-February, the application for exemption in Connecticut is still pending. 

Your Role in the Change 

One action item resulted from the teleconference call: each state member of IMERC is to 

issue a letter to the various standards development bodies to make them aware of the 

coming restrictions on mercury-containing devices and encourage them to begin the 

process of converting existing methods or developing new methods, using alternative 

devices and standards. This conversion process will take some time and will require the 

expenditure of significant resources by everyone involved in developing the alternative 

processes. As most standards development organizations are based on the work of 

volunteers, you can help in this effort to ensure testing procedures are properly updated in 

a timely manner. Remember the World Wars I and II posters that said, “Uncle Sam 

Needs YOU!”? Maybe we should rework that slogan to say, “Your standards 

development body needs YOU!” 

Changes are coming to the portions of our measurement world that rely on devices 

containing mercury. At least eleven states are restricting the sale or use of items 

containing mercury. Your state may be next. Now is the time to begin preparing for the 

time when your mercury-containing measuring instruments can no longer be used or 

replaced, as it is likely any exemptions issued by a state will have a defined expiration 

date after which an alternative must be used. Contact your standards writing bodies, 

ASTM, ANSI, NCWM, FDA, USP, etc., and encourage them to speed up the process of 

developing alternatives to measuring instruments containing mercury. 

One caution however—some alternatives currently being suggested for temperature 

instruments will themselves be environmental hazards requiring special disposal 

procedures and controlled waste streams. Be sure to fully investigate options and identify 

all environmental issues before adopting replacement instruments so that one hazardous 

material is not replaced by another. 

Volunteer your time and services to develop updated standards to replace the ones that 

now require mercury-in-glass thermometers. You can make a difference and you need to 

start now!