How harmful is it to turn onions?

Original title: Onion color, how harmful is it?
recent days, a news brush screen circle of friends, the content is cooking, stir-fry can not leave the onion was actually dyed. It's true. According to reports, the market in Guizhou appeared a "colored onion", this kind of onion with a paper towel will appear slightly blue. A testing department in Guizhou Province tested 20 samples of scallions, and 7 samples contained more copper than their own nutrients. Experts speculate that this may be due to the use of Bordeaux fluid.
this thing really sounds scary, long-term consumption of sprinkled Bordeaux liquid onions on the human body how harmful? What is Bordeaux liquid? Jiangsu disease control experts, Bordeaux liquid by the "copper sulfate and raw lime and water" configuration, is a "sky blue gel suspension." When Bordeaux liquid is sprayed on the surface of a plant, it is adsorbed to the surface of the plant because of its adhesion. Plants in the metabolic process will secrete acidic liquid, coupled with bacteria in the invasion of plant cells secreted acid, so that a small amount of copper sulfate in Bordeaux liquid into soluble copper sulfate, resulting in a small amount of copper ions (Cu2 plus), copper ions into the bacteria cells, so that the protein in the cell solidified. At the same time, copper ions can also destroy certain enzymes in their cells, thus making the metabolic action of bacteria can not be carried out normally. Under the influence of these two effects, the bacteria "poisoned" to death.
The scallions contain chloroplast, and the core of chloroplast is "a ring containing magnesium ions (a ring-like structure)," while magnesium ions are more active, easy to lose, chloroplast is easy to degrade, onion leaves show "yellow", and when copper ions instead of magnesium ions into the rings, the structure will be very stable, when copper ions-led chloroplast will show green. Therefore, Bordeaux liquid not only sterilization, but also often as a "color protector" to help plant color protection, so that the leaves to maintain green for longer, improve the sale of products.
it harmful to the human body to remove the colored onions? Copper element is actually a "human essential mineral element", the body once lack of copper, easy to affect health. But many home-made foods contain a certain amount of copper, and the daily diet can get enough copper, so there is almost no "copper deficiency" problem. The bactericidal factor of Bordeaux liquid is "copper ion", and its potential toxicity is actually copper ion. Although copper is a "heavy metal", it is not the same as arsenic, lead and other elements of the "toxic heavy metal."
, the human body's daily intake of copper more than 64mg, easy to induce copper poisoning, nausea, diarrhea, blood urine and other symptoms. A team of the Agricultural University of China conducted a "sub-slow toxicity study" on Bordeaux liquid and obtained non-toxic dose data from rats. The data is "multiplied by 100 times the safety factor" to the human body. It was concluded that it was safe for an adult weighing 60kg to consume no more than 8mg of copper per day. According to the results of Guizhou testing department, even according to the highest copper content of the sample calculation, daily intake of 2.17 kg of onions to achieve this amount. In fact, onions are just seasoned vegetables, and the average person doesn't eat 2.17kg of onions a day.
9 types of crops (tomatoes, citrus trees, cucumbers, peppers, potatoes, apple trees, grapes, rice, tobacco) are suitable for Bordeaux liquid, which do not contain onions. That is, although there are no health and safety risks, the use of Bordeaux liquid on onions is not permitted. Copper ions dissolve in water. If you are not sure, before eating, properly soaked and completely washed, you can wash off most of the copper. At the same time also remind small partners, daily life do not be too biased towards "particularly bright dishes", as far as possible to large supermarket chains to buy vegetables, reduce security risks; (Reporter Yang Yan)