Global mercury treaty could make local fish safer

It didn’t make many headlines at the time, but delegates from 140 nations earlier this month quietly signed the first-ever global treaty to reduce mercury emissions, a move that could help make Northland fish safer to eat.

The treaty, reached in Geneva, Switzerland, after years of negotiations, is aimed at reducing human-caused mercury emissions from smokestacks, gold mining and other sources — mercury that can float around the Earth before falling in rain and snow, sometimes thousands of miles from the source.

That mercury can transform into highly toxic methylmercury in wetlands, lakes and rivers, building up in fish and then in animals that eat fish, including loons, eagles and people.

Minnesota, Wisconsin and most other states have issued fish consumption advisories, warning anglers and others to limit their meals of some fish, such as walleye and northern pike. The advisories even warn pregnant women and children not to eat larger fish at all. The warnings are aimed at preventing accumulated toxic mercury buildup known to cause developmental and neurological damage, especially in fetuses and young children.

The United Nations environmental program reported this month that the amount of mercury falling into the top layer of the world’s oceans has doubled in the past century. Some mercury comes from natural sources, such as volcanoes. But it’s believed the big increase in recent years has come from human sources — nearly 2,000 tons per year into the air and another 1,000 tons directly into water.

Supporters of the new treaty say any reduction in how much mercury goes up and later falls to Earth will help reduce the amount of toxic mercury getting through to people.

“Everyone in the world stands to benefit ... in particular the workers and families of small-scale gold miners, the peoples of the Arctic and this generation of mothers and babies and the generations to come,” said Achim Steiner, U.N. environment program executive director, in a statement Jan. 19 as the treaty was approved.

Stopping the source

The treaty sets controls and reduction targets for many industries, products and manufacturing processes that use mercury, focusing on four main areas: the global supply and trade of mercury; the use of mercury in products and industrial processes; efforts to reduce emissions from small-scale gold mining in poor nations; and measures to reduce emissions from coal-fired power plants and metals production facilities such as smelters.

If and when a real reduction in mercury is achieved by the treaty, the results could be seen relatively quickly, said James Hurley, project director of the University of Wisconsin Water Resources Institute. Recent research headed by Hurley found that new mercury added to a lake shows up rapidly in the food chain. But Hurley’s work also found that mercury levels drop in fish shortly after the level of mercury entering the lake goes down — within the first year for minnows and soon after for bigger fish.

“The treaty really seems to try to tackle the sale and movement of mercury and how much mercury is out there going into small-scale gold mining. What we’re seeing now is that the amount of mercury one person is using for this kind of mining could be the same as a day’s worth of mercury from one coal plant,” Hurley said, noting recent estimates put mercury used for gold mining at more than one-third of all global emissions.

Mercury is used as an amalgam to bind with the gold, and later is burned off so the gold can be sold. The use of mercury has dramatically increased along with the skyrocketing price of gold in recent years.

“If they can really get a handle on that part of it, and also go after the emissions from coal plants and other industrial sources, we could see a real reduction in the amount of mercury in the atmosphere,” Hurley added. “And that would translate to less mercury going into our lakes. We’d see a corresponding reduction in the food chain.”

Mercury migrates here

Minnesota already has been taking action, for more than a decade, to reduce mercury from products such as batteries, thermostats, switches and light bulbs. The state also cracked down on mercury in dental implants and even mercury that went up the smokestacks of crematoria. The state also was among the first to require power plants to reduce mercury emissions, and now the federal Environmental Protection Agency has followed suit nationwide. Iron Range taconite plants, among the largest sources of mercury emissions in the state, also are moving to reduce smokestack mercury.

But state researchers say that, on average, only about 10 percent of the mercury that falls into Minnesota lakes is from Minnesota sources. Nearly one-third of the mercury deposition in Minnesota is from human sources far away — so-called global emissions, said Rebecca Place, mercury program manager for the Minnesota Pollution Control Agency.

That’s why, after all of Minnesota’s efforts, the amount of mercury in fish hasn’t declined much in many cases, Place said.

“We can’t solve the problem of mercury in Minnesota fish tissue only with actions in Minnesota. So seeing a global effort to tackle this problem really does seem like a big step forward,” Place said. “It’s going to take years to see the actual reductions from this treaty. ... But it’s still important that this is being addressed at a global level.”

Many Northland residents were jolted a year ago when the Minnesota Department of Health released a study that showed 10 percent of all babies born in the Lake Superior region of the state have levels of toxic mercury in their bloodstreams above the 5.8 micrograms per liter that the EPA considers safe. Some went as high as 211 micrograms per liter. Fetuses, infants and children are most at risk from mercury exposure because even small amounts can harm the developing brain and nervous system.

The health department, with federal funding, is conducting an intensive follow-up study in Cook County to find out how to reduce pregnant women’s exposure to mercury, which is probably coming from fish the mothers eat.

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