This is an article from the spring 2018 issue of LSA MagazineRead more stories from the magazine.


If someone says you’re “mad as a hatter,” blame it all on mercury poisoning. From the mid-18th century into the 1950s, craftspeople who made fancy hats often would line their products with felt, a material they created by applying the silvery metal mercury—a naturally occurring element that is liquid at room temperature and easily evaporates—to animal pelts. Their frequent exposure to mercury vapors gave hatters tremors, vision loss, social anxiety, delirium, hallucinations, and other symptoms.

In the 1950s, mercury was showing up everywhere. American and European manufacturers put mercury in thermometers, fluorescent light bulbs, thermostats, cosmetics, batteries, electrical switches, blood pressure cuffs, and even “silver” dental fillings. Mercury tainted the smoke from coal-fired power plants. Factories leaked mercury while making chemicals and plastics. Through leaks, broken thermometers, and landfill waste, mercury escaped from our products into the environment. 

Toxic mercury has increased in the environment over time—we know this partly because of the birds in the research collection at the University of Michigan Museum of Zoology (UMMZ). For a recent study, Canadian researchers visited the UMMZ and other museums across the United States looking for ivory gulls that curators had added to collections as far back as 1877. The researchers turned to museum collections because, in the wild, ivory gulls are rare. In Canada, their numbers have dropped by more than 80 percent since the 1980s, which makes collecting them for research neither easy nor advisable.

The researchers plucked feathers from the museum gulls and extracted the mercury trapped inside them. In birds that lived between 1877 and 2007, their feathers’ mercury concentrations showed a whopping 45-fold increase—meaning that for 130 years, the gulls’ mercury levels had risen an average of 1.6 percent each year.

In another mercury study, two scientists from U-M’s School of Public Health plucked feathers from yellow-billed loons at the UMMZ and elsewhere. In these birds, toxic mercury concentrations had doubled since 1845.

Getting a bead on mercury levels is important because the substance is so debilitating. Mercury pollution is no good for birds. The toxin causes problems with breeding, egg hatching, and chick health in some species. And of course, the neurotoxin is no good for humans, either. It drives adults insane while destroying their bodies, and it’s especially toxic to young kids and growing fetuses. 

Mercury also is a global pollutant. When the element goes airborne, it blows around the world with wind currents, sometimes contaminating places far from its origin, falling back to Earth in dust, rain, and snow.

All this bad news could put a frown on the staunchest optimist. But not LSA Biological Station alumna Linda Greer, director of the health program at the Natural Resources Defense Council (NRDC). She has fought against all odds to stop the spread of toxic mercury.

A Cure for Mercury

Greer spent five summers at the University of Michigan Biological Station (UMBS) in the 1970s. As a 19-year-old undergraduate coming to UMBS from another university, she was the youngest student at camp her first summer. She was studying French at the time, but UMBS got her hooked on science. She returned as a graduate student, then as a researcher, and later to teach. Last year she served as its interim director.


Mercury accumulates up the food chain, with highest concentrations in top predators, including tuna and humans. That’s why your canned tuna should be “can’t tuna” more than twice a week.


In 1991, Greer began a major project with the NRDC to reduce the negative health effects of pollutants. She tackled this huge project by homing in on a single pollutant, which would make her goal more manageable. “I was doing a review of the biggest pollutants in air, water, food, and shelter, because with so many chemicals out there, it pays to work on the ones that matter the most among 80,000 chemicals in commerce,” Greer said.

“Reviewing the biggest contaminants in food, I expected to find a pesticide. But I discovered that, actually, the biggest pollutant was mercury in fish.”

Greer quickly realized that the mercury problem was an international one. The United States phased out excessive mercury use once people realized its dangers, and manufacturers also developed cheaper and better technology that made reducing mercury use easier. But factories had a lot of mercury on their hands that they wanted to get rid of, and the most popular solution was to recycle the offensive material by offloading it to developing countries.

But people didn’t realize the tradeoff involved in handing off excess mercury for use in other countries. Greer described it as “basically shipping mercury halfway around the world to have it come right back at us as air pollution.”

Greer targeted the global mercury trade as the most efficient way to have the biggest positive impact on the problem. Her massive but achievable goal was to get the United States to stop selling its surplus mercury to other countries around the world.

Her job got easier when then-Senator Barack Obama reached out to the NRDC. When he served as a senator, Obama got the Chicago Tribune every day, and he read an article about mercury pollution in the Great Lakes. Obama’s team got in touch with Greer and said, “The senator would like to do something about the problem of mercury in fish; do you have any ideas?”

Equipped with information from Greer and the NRDC, Obama teamed up with a Republican senator from Alaska to push a bill through the Senate that proposed a ban on mercury exports from the United States. A Maine congressman got the ball rolling in the House of Representatives, and the bill was signed into law in 2007.

Starting in 2010, Greer and her colleagues worked with the United Nations and more than 100 countries to write and agree on an international treaty to reduce the use and release of mercury around the world. For each session of negotiations, Greer said, “We spent one week in a very formal setting with a group of mostly strangers to deliberate the value of a legally binding treaty to reduce mercury pollution across the world.”

The treaty negotiations began the way most people might picture a big international meeting: A diverse assortment of people seated quietly at long desks wearing translator earpieces. But toward the end of each session, Greer said, “It’s just like cramming for finals or something. The last day, people aren’t ready, and it’s literally an all-nighter. People haven’t eaten. It’s just like college.”

After three years of negotiations, 128 countries signed the binding international treaty about mercury in 2013. They agreed to restrict global trade, establish air emission controls, phase out extraction from mines, and otherwise address the problem in tangible ways.

“The treaty sets in motion everything that needs to happen,” says Greer, but noticeable environmental improvements will take time. “Our watersheds are saturated with mercury from all the years of pollution, even after we turned off the spigot.”

Illustrations by Lisa Haney