Researchers from Toulouse, Massachusetts (USA), Ohio (USA) and the Netherlands have questioned the mercury concentration in the world’s oceans, in order to deduce the most contaminated fish.
Thanks to oceanographic measurements made across the oceans and recent scientific expeditions, researchers have successfully compared and calculated the dissolved mercury content of the Pacific, Arctic, North Atlantic and South Atlantic oceans.
They then observed that the deep waters of the Atlantic Ocean as well as the intermediate waters were abnormally rich in mercury, compared to the same data from other oceans.
The mercury rate would thus have increased by 150% in intermediate waters, and would have tripled in surface waters, compared to the mercury rate before human activity.
Scientists have deduced that this exceptionally high level of mercury is due to human activities along the North Atlantic, in particular through the combustion of oil and mining.
Significant contamination, especially in predatory fish
The accumulation of mercury in the ocean would not be of concern if it did not result in contamination in the food chain.
Unfortunately, the Pisces reared or fished in the North Atlantic naturally tend to accumulate mercury in their tissues.
The fish to avoid on our plates are then predators (swordfish, sharks, lampreys, marlins …), more exposed because of their presence at the top of the marine food chain.
Pregnant women and young children, special precautions
At high doses, mercury is associated with neurological disorders (in particular multiple sclerosis). The National Agency for Health, Environmental and Occupational Safety (ANSES) therefore recommends consuming fish twice a week, to benefit from its nutritional properties, and to diversify the species of fish consumed.
For pregnant or breastfeeding women as well as for children under 30 months, ANSES recommends avoiding the most contaminated fish (predators) and limiting the consumption of North Atlantic fish to 150g / week for the pregnant or breastfeeding women, and 60g per week for children under 30 months.
Source:
A global ocean inventory of anthropogenic mercury based on water column measurements, published in the scientific journal Nature on August 6, 2014.