Ban spells the end of the mercury glass thermometer

It was one of Daniel Fahrenheit’s most famous inventions. Now, after nearly 300 years as a household fixture, the mercury glass thermometer is bound for the museum.

The Canadian government announced plans Monday to ban the manufacture, import and sale of most products containing mercury, including glass thermometers. Ottawa has yet to set a timeline for the ban.

It’s a move that stems from Canada’s involvement with the UN Environmental Program Mercury Partnership, which aims to reduce the release of toxic mercury into the environment.

Environment Minister Peter Kent said the proposed regulations would eliminate about 4.5 tonnes of mercury in products currently entering the Canadian marketplace each year.

“It is the first time that the government of Canada is broadly regulating mercury found in manufactured products,” Mr. Kent said in a statement.

Glass thermometers contain a small amount of mercury, a potent nerve toxin linked to birth defects and brain damage in children. The regulations are subject to a 75-day comment period, with the government promising to take a “common-sense approach” to all mercury-containing products.

But with the prohibition of mercury thermometers, it might soon be a bit of a misnomer to say, “The mercury dipped to …”

Although mercury thermometers are used in weather stations across the country, Environment Canada will phase them out by 2016, said spokesman Mark Johnson.

South of the border, mercury glass thermometers are also heading for extinction.

Since 1901, the U.S. National Institute of Standards and Technology has been calibrating mercury thermometers for manufacturers, including some 20 Canadian companies. That comes to an end on Tuesday when the NIST will stop providing the service.

The termination of the service is a natural phase-out, said Greg Strouse, group leader for temperature and humidity at NIST.

“When I first joined NIST about 23 years ago, we were calibrating about a 1,000 thermometers every year,” Mr. Strouse said. “Last year, we did only four – and none for Canadian companies.”

The retail sale of mercury thermometers is banned or restricted in at least 18 U.S. states., making it not worthwhile for the NIST and manufacturers to continue with the calibration and production of mercury glass thermometers.

Mercury thermometers work in response to heat; the mercury expands as the temperature rises and contracts as it falls. Before the advent of electricity, mercury thermometers were the popular choice. These days, digital thermometers give temperature readings based on variations in the electrical resistance of the metals inside the device.

But it’s not just for environmental reasons that digital thermometers are the preferred choice. Mr. Strouse said mercury thermometers are accurate usually within one degree Celsius, whereas digital thermometers are usually accurate within one-tenth of a degree.

While many people probably have stashed mercury glass thermometers in their medicine cabinets, the medical industry ditched them in favour of digital thermometers in the 1980s.

Not all mercury-containing products will be banned. Ottawa does not intend to outlaw dental fillings containing mercury. Amalgam fillings are not considered a risk to human health, according to a government consultation document.

“The government is taking a common-sense approach. Mercury will continue to be used in several important and necessary applications,” Mr. Johnson said.

The government also plans to exempt compact-fluorescent light bulbs. While they contain a small amount of mercury, the energy-efficient bulbs reduce its overall presence in the environment, the government said, through reduced demand on coal-fired plants, which are one of the country’s largest sources of mercury emissions. Scientific instruments containing mercury will also be allowed.

As part of its proposal, Ottawa also plans to require better information on product labels about safely disposing of items containing mercury. At the moment, any product containing mercury should be taken to a hazardous waste depot.

The facts on fillings: Why are dental fillings containing mercury not banned?

According to Heath Canada, current evidence does not indicate that dental amalgams cause illness, while alternative materials are more expensive to use, technically difficult for dentists to place and not as strong or durable.
It is true that inorganic mercury in dental amalgams can convert to methylmercury when released into the environment. But this kind of conversion does not happen in people’s mouths.
The risk of pollution is much higher from a glass thermometer should it shatter and release mercury into the environment.

What mercury-containing products is Ottawa proposing to ban?