Hot water in and poisonous water out? CCTV exposed unqualified thermos cups, heavy metals exceeding the standard seriously, how to distinguish
In order to reward her daughter who is serious about her studies, Ms. Zhao bought a thermos cup with a beautiful pattern on the Internet. Her daughter likes this gift very much and uses it to hold water every day.
But surprisingly, her daughter began to experience nausea, vomiting and dizziness after using the thermos for a week .
At first, Ms. Zhao thought that her daughter had a cold, so she bought some cold medicine for her, and didn't think about the problem of the thermos.
But after taking the medicine for a few days, not only did her daughter's condition show no signs of improvement, but it got worse.
So Ms. Zhao hurriedly took her daughter to the hospital for a comprehensive examination. It turned out that her daughter had symptoms of heavy metal poisoning, and the culprit was the thermos cup with beautiful patterns that Ms. Zhao bought.
1. Hot water enters poisonous water and exits? CCTV exposed unqualified thermos cups
The weather is getting colder and colder, and many people start to drink hot water with thermos cups, but the quality of thermos cups on the market is uneven. In order to make huge profits, some unscrupulous businesses use industrial-grade 201 stainless steel to pretend to be food-grade 304 stainless steel to produce thermos cups.
The use of this thermos can easily lead to excessive levels of heavy metals such as chromium and manganese. Drinking water from this thermos for a long time may cause rhinitis, loss of appetite, pharyngitis and other upper respiratory tract diseases, and even lead to lung cancer.
A reporter from Huashan.com has visited some stores. The price of thermos cups sold in large supermarkets is about 30-200 yuan. Each thermos cup is marked with the material and detailed product information, and the bottom of the stainless steel liner in the cup is also marked. material.
The reporter also visited several small commodity wholesale markets and found that the price of thermos cups here is about 10-50 yuan, but the outer packaging and inner liner of the cups are not marked with materials, only a barcode is attached to the bottom of the cup, and some will still be opened when opened. There is a pungent smell.
When the reporter asked about the material, the boss said that it was not written, but you can buy it with confidence.
CCTV has also exposed the issue of thermos cups. The staff of the Beijing Consumers Association conducted random inspections on 50 thermos cup products. After testing, 19 thermos cups failed , mainly because the product logo and liner material did not meet the national standards. .
Lv Baoli, director of the chemical laboratory of the Beijing Light Industry Quality Inspection Station, explained that the main reason is that some thermos cups do not use 304 stainless steel. The stainless steel used in these unqualified products contains high manganese and relatively little nickel, so the corrosion resistance is relatively high. Poor, it is easy to lead to heavy metals exceeding the standard.
Afterwards, the experimenter conducted a test, put the prepared 5% hydrochloric acid solution into the thermos cup, and detected the content of heavy metal ions after 24 hours. It was found that the heavy metals precipitated in a thermos cup worth 30 yuan exceeded the standard seriously, and the inner wall also It was severely corroded and even turned black.
The reason why the thermos cup can keep warm is not complicated. The stainless steel thermos cup has a double-layer structure. The two layers of stainless steel on the cup body and the inner tank are evacuated after being combined by welding, and the vacuum will not transfer heat;
Silver or copper is plated between the two layers of stainless steel on the cup body and the inner tank to reduce the heat lost by radiation; in addition, the cock of the thermos cup is well sealed, which can reduce the heat loss by convection.
The thermos cup is not only about the appearance, when you hold it in the palm of your hand to drink water, you will find that the material is more important than the appearance.
At present, most thermos cups are made of stainless steel. Stainless steel materials are mainly divided into three types, codenamed 201, 304 and 316.
201 stainless steel: high manganese content, poor corrosion resistance, and low price, but it can only be used in the manufacture of industrial supplies . If it is used in the inner liner of the thermos, it will easily lead to the precipitation of manganese, which will cause harm to human health.
304 stainless steel: It is a food-grade stainless steel. It contains 18% chromium and 8% nickel. It is acid resistant and has good corrosion resistance . However, it is prone to pitting corrosion when encountering substances containing chloride ions.
316 stainless steel: On the basis of 304 stainless steel, there is more metal molybdenum, so it has better corrosion resistance , but the cost is relatively high , most of which are used in high-precision fields such as medical and chemical.
Everyone is worried that they will choose unqualified products. When buying a thermos cup, someone mentioned that a thermos cup that can be attracted by a magnet is a good quality thermos cup. Is this true?
At present, the more common 304 and 316 stainless steels on the market are non-magnetic austenitic stainless steels, and the main alloying elements contained are relatively expensive iron, nickel, and chromium; even low-nickel and manganese-containing austenitic stainless steels do not have Magnetic, although the price is cheaper, but the safety and performance are not bad, so you can't use magnetism to judge the quality of the thermos.
When buying a vacuum flask, pay attention to the following points:
"Look" : The stainless steel cup body of the vacuum flask must meet the relevant requirements in GB 4806.9-2016 "National Food Safety Standard for Food Contact Metal Materials and Products", and see whether the marked material composition and type are qualified. Simple information such as "stainless steel", "high-quality stainless steel"; the sealing cover of the vacuum flask should be made of safe and heat-resistant PP material.
"Touch" : The surface of the outer tank and inner tank of the thermos should be uniformly polished, without scratches, bumps or burrs, and the welded joints should be smooth.
"Smell" : The cup has no irritating odor.
"Try" : Pour in boiling water, then tighten the lid of the cup, and hold it by hand after 2~3 minutes. If there is no obvious heating, it means that the heat preservation effect of the thermos cup is good; then turn the cup upside down for 4~5 minutes to see if there is any leakage If there is no leakage, it means that the sealing performance of the cup is good.
3. Will making tea in a thermos cup cause cancer?
Some people use thermos cups to make tea, so that they can drink hot tea at any time, but some people say that using thermos cups to make tea is unhealthy and easy to poison. The reason for this statement is that tea scales are easily produced when making tea with a thermos cup, so some people worry that the tea scale will adhere to the inner wall of the thermos cup for a long time and corrode the stainless steel, resulting in the dissolution of heavy metals.
In fact, although the tea itself has a weak acidity and alkalinity, for a stainless steel thermos cup that meets the standard, there is no need to worry about the dissolution of alloy elements , because the chromium element contained in stainless steel can ensure the formation of a passive film on the surface of stainless steel. , can protect the stainless steel substrate.
Even if a trace amount of alloying elements is corroded and dissolved, the alloy elements such as chromium, nickel, manganese, molybdenum and other alloying elements in stainless steel for tableware are all trace elements necessary for our human body and will not affect our health.
Although making tea in a thermos cup will not cause poisoning or cancer, it is not recommended for making tea, because soaking tea in high temperature for a long time will affect its taste and nutrition, so that the tea polyphenols in the tea are fully dissolved, and the aromatic substances And the active substances are destroyed by heat, resulting in a thick, dark tea soup, which is more bitter to drink.
In addition, it is not recommended to put milk soymilk in a thermos cup , because both milk and soymilk are high-protein foods, and long-term storage at a suitable temperature can easily cause bacteria to multiply. Once the milk and soymilk breeds bacteria, it will quickly grow Deterioration and rancidity, it looks like flocculent tofu brain, and it is easy to cause diarrhea after eating.
As a daily necessities, for the sake of health, when we choose a vacuum flask, we must pay attention to choosing a stainless steel vacuum flask that meets the quality standards.
References:
[1] "Hot water becomes "poisonous water" and there are many hidden dangers in inferior thermos cups. Huashan Net. 2020-12-14
[2] "What is the thermal insulation principle of the thermos cup? Learn about heat transfer". People's Daily Online. 2019-08-08
[3] "Did you choose the right thermos cup? Be careful not to step on thunder at 6:00". Healthy China. 2022-02-08
[4] "Is it poisonous to make tea in a vacuum cup? Stainless steel is not so fragile". The Paper. 2019-11-19
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