Your Tuna Is Getting More Toxic

Mercury levels in the Northern Pacific have already increased a staggering 30% in about 15 years, and are expected to rise another 50% by 2050. This stunning increase is a direct result of China's rapid industrialization, which has included the construction of as many as one new coal-fired power plant a week, by some estimates.

Mercury is a naturally occurring element, but it's a food supply contaminant because of industry. Mercury is spewed from the smokestacks of coal-fired power plants, cement kilns (which burn coal, and use limestone, both of which can contain mercury) and certain types of mining (gold mining uses mercury to process the rock).

When mercury enters the air, it eventually rains down and is incorporated into aquatic food chains. Larger predatory fish like tuna, swordfish and shark, can accumulate unhealthy doses because they spend a lifetime eating smaller fish and aquatic creatures. Women who are pregnant or nursing, and young children, are most at risk of mercury poisoning, because it can lead to permanent brain damage.

The data comes from a new federal study by the U.S. Geologic Survey that was published in the peer-reviewed scientific journal Global Biogeochemical Cycles.