2012-12-11 17:09:30
Mercury, methylmercury, what is it?
Mercury is a metal present naturally in trace amounts in the environment. Essentially released by the earth’s crust into the air, it is then dispersed in soil, water and sediments. It also spreads in nature due to emissions generated by human activities: mining, metallurgy, processing of paper pulp, combustion of waste and fossil fuels in particular. Very volatile in its elemental form, it is following chemical transformations that mercury becomes toxic and easily absorbable by the body (bioaccumulative). Present at low concentrations in water or sediments in its methylated form, called methylmercury, it can concentrate very strongly in aquatic organisms, its content tending to rise along the food chain, each time one species eats another.
Why is the Agency working on this substance?
At high doses, methylmercury is toxic to the central nervous system of humans, particularly during in utero development and early childhood. This substance can thus cause mild behavioral disorders or developmental delays in children exposed in utero or following birth, even in the absence of toxic signs in the mother.
Fish consumption is the main source of human dietary exposure to methylmercury. The level of contamination of fish varies depending on the species. It tends to be higher in those at the top of the food chain (large predators).
What does the Agency recommend?
Since 2002, the Agency has issued 3 opinions to assess the health risk linked to the consumption of fish contaminated by methylmercury. Throughout its opinions, the Agency has refined and clarified its recommendations with regard to the evolution of international guide values and the data available on mercury, on the food consumption of different categories of the population and on the contamination of different types of Pisces.
For the entire population, ANSES considers that the consumption of fish does not present a health risk with regard to the risk linked to methylmercury. In fact, the population’s intake of methylmercury is lower than the tolerable daily intake.(1) defined by the World Health Organization.
In view of the nutritional benefits linked to the consumption of fish (essential fatty acids, proteins, vitamins, minerals and trace elements), the Agency recommends:
- eat fish twice a week, including fatty fish (salmon, mackerel, sardines, anchovies, smoked trout, herring, etc.);
- to diversify the species of fish consumed.
For pregnant and breastfeeding women and young children (under 30 months), the Agency recommends taking special precautions:
- as a precaution, avoid consuming the most contaminated fish: sharks, lampreys, swordfish, marlins (close to swordfish) and sikis (variety of shark);
- limit the consumption of fish likely to be heavily contaminated(2) 150 g per week for pregnant and breastfeeding women and 60 g per week for children under 30 months.
(1) The tolerable daily intake is the quantity of substance that can be ingested daily by the consumer without harmful effects on their health.
(2) anglerfish or monkfish, Atlantic sea bass, bonito, eel and glass eel, emperor, orange roughy or Mediterranean roughy, grenadier, Atlantic halibut, megrim, mullet, pike, palometa, Mediterranean capelin, common pailona, rays, large redfish, Atlantic sailfish, silver scabbardfish and black scabbardfish, sea bream, pageot, black or stromatoe escolier, redfish, snake escolier, sturgeon, tuna…
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