Published43 minutes ago
Levels of mercury persist in tuna, decades after pollution controls were introduced to limit emissions, scientists say.
The poisonous element is released by mining and burning coal and ends up in the ocean, where it builds up in fish.
Levels have fallen dramatically in the atmosphere – but remained stable in tuna since 1971.
Very old mercury lurks deep in the ocean and wells up into the waters where the tuna swim, experts say.
Mercury entering marine ecosystems is converted into methylmercury, the most dangerous form of the chemical.
It builds up in tuna when they consume contaminated prey.
And humans are then exposed to the element when they eat the fish, one of the most widely consumed around the world.
Mercury poses a particular threat to unborn babies and small children but has also been linked to cardiovascular disease in adults.
Concerns over exposure to mercury have seen governments the world over try to reduce activities that released the chemical into the atmosphere.
The major sources include:
Even the cremation of human bodies with amalgam fillings adds to the total in the air.
Restrictions on many of these activities have seen emissions levels in the atmosphere fall by about 90% since 1990.
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