Agroaldea
MERCURY, LEAD AND CADMIUM ARE THE MAIN; AT SEA BEING PASSED A SOLUBLE SOLUBLE.
The toxicity of some fish routinely consume is mainly due to the high presence of mercury in the meat. I eat, logically, means that heavy metal or ingest, which is the same, endanger our health.According to the results of a US study on exposure to methylmercury in fish -the common form of organic mercury in the food chain and the most toxic chemical form thereof- it is recommended to seek alternatives to the most dangerous species, such as swordfish, the shark, tuna or, for example, the salmon.
Published by the prestigious scientist Edward Groth and reviewed by other experts in the field, it is recommended to avoid these fish or, at least, not abuse them if two or more weekly servings of fish consumed.
When we speak of heavy metals we are referring to metallic chemical element whose density is high, as well as its power of toxicity, even at low concentrations. They are not degradable, therefore they can not be destroyed. They join living organisms through the air, water and soil passing food or food chain.
Among those affecting the fish are mercury (Hg), The Lead (Pb), and cadmium (Cd). In the aquatic environment they undergo transformation passing inorganic metal to organic metals, i.e., soluble has liposoluble, so they are not excreted and are bioacumulándose along the entire food chain in the tissues and viscera of fish. Hence in the last links of the chain has more toxic accumulated thus becoming available to man.
Furthermore the greater distribution of heavy metals in water and in both plant and animal aquatic species by altering the chain and causing serious effects on human health to be able to pass the blood brain barrier due to their lipophilicity.
Why heavy metals accumulate in fish?
The incorporation of heavy metals into our diets could be summarized as follows: toxic spills occur metals, passing water, the plankton absorb smaller organisms or algae, hence small fish, and larger fish that eat large quantities of small fish, accumulating chain heavy metals. After we eat these larger fish. Although it should insist that it would be necessary to eat a lot of these fish to have harmful effects.
An example would methylmercury. When mercury is released into the environment it becomes organic compounds by methylation processes in which are probably involved bacteria and other microorganisms. Thus entering the food chain, and it is transmitted by each of its links to go to accumulate in individuals at the top, i.e., we. This process is known as biomagnification.
Exposure to mercury occurs primarily through ingestion, basically fish, Besides the danger of dental fillings. When you set or remove a dental filling, a small amount of mercury vapor can be released, producing kidney and brain damage. Although 2004 a study by the FDA (Foods and Drugs Administration) in the United States it concluded that the damage caused by the use of these fillings is negligible, except in a few cases of allergic reactions.
Lead exposure occurs by inhalation and consumption equivalently. Children are the main victims of exposure to this metal, and it is associated with some types of anemia, to lower levels than initially believed it. Although the use of leaded gasoline has decreased, this metal remains in paints and even in some containers food containers with leaded glazes.
Levels of cadmium exposure is higher in smokers than in nonsmokers, where food is the main cause of exposure. The main consequence is increased kidney damage and fragile bones and, as recently it found, This damage can be caused by a lower amount than was thought.
Mercury cycling
While in sardines just have 0.01 ppm (part per million) mercury, in sharks we have since 1 ppm to 4 ppm. When we consume these foods, methylmercury is easily absorbed in the digestive tract, which forms a complex with the amino acid cysteine, similar to another amino acid present in the body, methionine, what it facilitates entry into cells.
Once in the bloodstream methylmercury it accumulates in the brain creating damage to the central nervous system. Although sometimes this complex is eliminated through the liver, It secreted into bile which separates methylmercury, contacting bacteria in the intestine and is separated into inorganic mercury and carbon. Once in its inorganic form it ceases to be absorbed by the intestinal tract, so it is mostly eliminated in the stool, a 90%.
The 10% remaining methylmercury that does not interact with bacteria is reabsorbed by the body, and the cycle begins again. It can take up to a year mercury levels to drop significantly.
find alternatives
The tuna, including canning, is a health hazard if consumed regularly, according alert studies and organizations like Ecologists in longline action. Without going further, canned tuna consumed in Spain has more than 0,2 mg of mercury per kilogram of fish, in front of 0,04 mg / kg of mackerel, according to a study published in the journal Scientific Research.
Returning to the earlier work, Groth explains that the key is to choose fish with low mercury to finish intoxicated. His advice is clear: for anyone who eat fish twice a week or more, is essential to choose fish with low mercury content and not abuse them, limiting the weekly rations equally.
Natural Resources Defense Council (NRDC) He wrote the following list warning mercury concentrations with fish:
– Avoid eating these fish for very high levels of mercury:
mackerel Giant, Needle*, Orange roughy *, Shark*, Swordfish*, Tilefish and tuna *.
– Consume less than 3 times a month for high levels of mercury:
Pez Azul, Mere*, Mackerel (Gulf), Chilean sea bass *, Tuna (canned albacore) and Tuna (Yellowfin).
– Consume 6 times or less per month for moderate levels of mercury:
Lubin (negro, lined), Tent, Cod (de Alaska), Corvinetas (sciaenidae), Halibut (Atlantic)*, Halibut (peaceful), Jacksmelt, Langosta, work, Rape*, Percha (freshwater), Black cod, Raya *, Pargo*, Tuna (canned), * Nice and Trout Marina (Corbina).
– Consume no limit these little seafood with mercury:
anchovies, Butterfish, Bagre, longs, Crab (USA), River crab, Gurrubata, turbot *, Pout (Atlantic)*, Hake, Herring, Mackerel (North Atlantic, Chub), Mujo, Acute, Percha sea, platija, Pout, Salmon (canned)**, Salmon (fresco)**, Sardina, Vieira*, shad, Shrimp*, Pacific halibut, Squid (chipirón), Tilapia (mojarra), White fish and Romero.
* This fish species is endangered, or is captured using methods harmful to the environment.
** Farmed salmon can contain PCBs, policlorobifenilo, chemical that affects health.