The 2013 Minamata Convention was named for the Japanese bay from which mercury-tainted fish left thousands of people with severe brain damage in 1956. Industrial wastewater had been dumped into the bay for more than 20 years.

So far, 128 countries have signed the treaty and 74 have ratified it.

"The Minamata Convention shows that our global work to protect our planet and its people can continue to bring nations together," UN environmental chief Erik Solheim said Wednesday. "We did it for the ozone layer and now we're doing it for mercury, just as we need to do it for climate change."

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Mercury was commonly used in batteries, fluorescent lights, felt production, thermometers, and barometers. These uses have been phased out. The treaty requires governments to stop mercury mining, continue to cut mercury use in industry and slash emissions.

Mercury is an extremely poisonous metal that never breaks down. Contact with it attacks the nervous system and can cause brain damage, severe emotional problems, coma, and even death. Children are especially at risk.

Mercury forms naturally in the environment but is also man-made for industrial uses.

"There is no safe level of exposure to mercury nor are there cures for mercury poisoning," the U.N. says.

Governments that signed the treaty must also meet tough conditions for storing and safely disposing mercury waste. (VOA)