The culprit behind the madness of hatters in the 19th century and commonly holding the top spot on the list of things to avoid for pregnant women and children, mercury is a toxic element that is recognized as a chemical of global concern. It has the ability to travel far and wide in the atmosphere, is tenacious in the environment, bioaccumulates in ecosystems and has significant deleterious effects on human health and the environment.

Notably, mercury concentrations accumulate in fish and journey up the food chain, finding its way onto the plate and potentially causing permanent damage to the nervous systems, with the greatest risk to pregnant women, women of childbearing age and young children.

And now according to a new report by the U.N. Environment Program (UNEP), mercury pollution in the top layer of the world's oceans has doubled in the past 100 years, courtesy of man-made industry – and in need of international cooperation to fix.

As well, concentrations in waters below the top layer have gone up by 25 percent, while rivers and lakes contain an estimated 260 metric tons of mercury that was previously held in soils.

The report reveals that hundreds of tons of mercury have leaked from the soil into rivers and lakes around the world. Emitted from sources like coal burning and small-scale gold mining, where it is used to separate metal from ore, mercury also comes from discarded electronic and other consumer products. Mercury in the air settles into soil and then finds its way to the water.

The report, which serves as an update on the agency’s previous analysis of mercury from 2002 and 2007, comes right before talks in Geneva next week between nations that will be negotiating a new legally binding treaty to reduce global mercury emissions. Previously, major industrial powers including the United States, China and India have only sought voluntary reductions.

UNEP's executive director, Achim Steiner, said mercury pollution remains "a major global, regional and national challenge in terms of threats to human health and the environment" but new technologies can reduce the risks.

Related story on MNN: How much mercury is in the fish we eat?

Mercury pollution doubled in last century, says United Nations
A new report finds that global mercury levels in the world’s oceans are rising at an alarming rate.