The push to get the mercury out

Researcher Dawn Cross calibrates a mercury thermometer using water's ice point as a reference, a service that will end March 1.
Researcher Dawn Cross calibrates a mercury thermometer using water's ice point as a reference, a service that will end March 1. (Gregory Scace)
By Danielle E. Gaines
The Gazette
Thursday, February 17, 2011

For 110 years, since the doors of the National Institute of Standards and Technology opened, scientists there have calibrated mercury thermometers to read correct temperatures for users in the aerospace, pharmaceutical, petroleum and other industries.

That legacy soon will end.

Beginning March 1, the Gaithersburg-based federal agency no longer will provide that calibration service. The move is part of a larger government program to reduce dependence on industrial mercury thermometers, which in some cases are less reliable than newer technology, said Greg Strouse, a physicist and leader of NIST's Temperature and Humidity Group.

The program is being led by the U.S. Environmental Protection Agency, which issued a memorandum in September 2008 calling for the phase-out of all mercury, non-fever thermometers used in EPA laboratories.

Mercury is a potent neurotoxin that can cause neurological and breathing problems, according to the Centers for Disease Control and Prevention.

Exposure to small spills from broken thermometers generally does not have demonstrable health effects, according to a federal Mercury Workgroup study from February 2009. But elemental mercury found in thermometers and used in industrial processes makes its way into streams, rivers and oceans if it is released into the environment. The mercury is absorbed by sea life and accumulates in larger fish that people eat.

Nearly all methylmercury exposures in the United States occur through eating fish and shellfish, according to the EPA.

Mercury spills are tracked in several national databases managed by the CDC, the U.S. Coast Guard, the American Association of Poison Control Centers and the EPA.

In 2009, poison control centers fielded 3,999 calls about mercury cleanup from broken thermometers and 3,632 calls for other mercury cleanups, according to the national nonprofit organization's annual report. The number of calls for broken thermometer cleanup has decreased in recent years, according to the Workgroup report.

The EPA is working to change federal and state regulations that require the use of mercury thermometers for certain industries by citing the standards set by international organizations, such as ASTM International - formerly the American Society for Testing and Materials - and the American Petroleum Institute.

About 300 of the nearly 700 ASTM standards have been changed to allow use of mercury-free liquid-in-glass and digital thermometers, according to NIST.

NIST research Dawn Cross is a leader in identifying alternatives to mercury thermometers. She says the remaining ASTM standards will be amended within three years to include procedures for switching to mercury thermometer alternatives, according to a news release from the agency announcing the end of the calibration services.

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