Cooking with raw water is not only toxic but also carcinogenic? Those who dare not use tap water to cook rice, check it out
Ding dong! Wechat received 2 new messages, Xiao Yang clicked in and found 2 articles forwarded by his mother:
"Don't use tap water to cook rice! Tap water contains chlorine, long-term consumption will cause cancer risk, please forward it to relatives and friends..."
"When cooking food with tap water, be sure to open the lid to boil the water, and then put the food to be steamed, otherwise the chlorine in the self-boiling water will be adsorbed on the food, and eating it will cause cancer! 》
After that, my mother continued to send messages, "Did you see it, don't drink tap water directly in the future, and don't use raw water directly to cook rice, you know? Experts say this has a risk of cancer ."
Xiao Yang saw that the content of the article seemed reasonable and well-founded, so he sent a private letter to ask Xiao Jiu, " Does chlorine in tap water really cause cancer? "
In fact, there have always been many "black pots" about tap water, and they have even been widely circulated, such as:
"Chlorine in tap water can cause cancer, cooking food in tap water can cause cancer "
"Boiled tap water has a shelf life of only 16 hours"
"The high incidence of kidney disease in Chinese is due to drinking too much tap water"
“……”
Today Xiaojiu will explain it to everyone.
1. Cooking with raw water is not only toxic but also carcinogenic?
In fact, chlorination of tap water is not a "feature" of China. Chlorine disinfection of drinking water has a long history in the world. Since 1908, the United States has used chlorine disinfection as an important disinfection method for urban water supply. Thanks to this, the mortality rate of people infected with typhoid fever in the United States has been greatly reduced .
Natural water naturally contains various bacteria, which are transmitted from the reservoir to every household through a pipeline system. If it is not sterilized, it becomes a "bacterial culture solution".
The best way to deal with sterilization is to control the source.
Therefore, the most commonly used sterilization method at present is to add chlorine—chlorine gas or chlorine dioxide, which has super oxidizing ability and can kill a variety of bacteria .
During the transportation of tap water, there may be multiple pollutions, such as: source pollution, secondary pollution caused by aging water pipe network, unreasonable or imperfect water disinfection methods, in order to minimize the possibility of water pollution, water will be left behind . Residual chlorine to achieve inhibition of bacteria, thereby ensuring the safety of the transportation process .
Can residual chlorine in tap water cause cancer?
In fact, the chlorine level in Chinese tap water is very low and safe. The World Health Organization (WHO) stipulates that the residual chlorine in tap water should not exceed 5mg/L, while China's regulations are stricter at 4mg/L .
In addition, the presence of chlorine does not necessarily mean that it is carcinogenic. The International Center for Research on Cancer classifies chlorine as a Category 3 carcinogen, that is, there is not enough evidence to prove its carcinogenicity.
Therefore, household water, as long as there is no irritating taste, do not need to worry about residual chlorine . Even if you use raw water to cook rice, you do not need to worry too much about the risk of cancer. After all, in the process of cooking, raw water also becomes boiling water, and the high temperature itself kill some bacteria.
2. After the raw water is boiled, the "shelf life" is only 16 hours. Is it true or false?
There are rumors that raw water turns into "cooked water" after being boiled, and the shelf life is only 16 hours, otherwise it is spoiled water, and frequent drinking will cause cancer.
Regarding the statement that "cooking food with tap water will cause cancer", Zhang Jianrong, director of the Experimental Center of the School of Chemistry and Chemical Engineering of Nanjing University, explained that if chlorine gas oxidizes food, chlorine gas will turn into chloride ions, which is the same as chloride ions in salt (sodium chloride). The same, harmless to people. Unless the food is oxidized and it changes itself, it has no effect on the human body.
After the boiled water is boiled, does it really have a shelf life? It’s right to drink the water as soon as possible, but to deduct the “expiration date” is a sin.
The water that is left for too long is mainly worried about pathogenic bacteria. Common pathogenic bacteria in life include Salmonella, Staphylococcus aureus, Escherichia coli, etc. These bacteria are basically eliminated during the heating process .
If you put the water bottle in the toilet without a cover, it is easy to be polluted by bacteria or impurities floating in the air. Such water is not recommended for drinking.
3. The high incidence of kidney disease in China is caused by tap water?
Where did the saying "Tap water causes kidney disease" come from? Some people think that after boiling tap water for a long time, there will be a layer of scale attached to the kettle. If people drink water with scale, it is easy to develop kidney stones.
What exactly is limescale? After the tap water is boiled, the calcium and magnesium ions in the water can be heated to form calcium bicarbonate, which is a white layer of scale that we see with the naked eye .
Minerals in water, especially calcium and magnesium, can partially meet the intake of mineral elements required by the human body. If you only drink pure water or mineral water, the minerals in the water will be removed, which is not good for your health.
A measure of the concentration of calcium and magnesium ions in water is called the "hardness" of water.
Generally speaking, if the hardness is lower than 150 mg/L, it is called "soft water", and if it is higher than this value, it is called "hard water". Soft water can also produce scale, but the amount is small and difficult to detect.
If you drink hard water for a long time, the calcium ions in the water combine to form calcium oxalate, which can promote the formation of urinary stones.
But it is not the lower the hardness of the water, the better. Studies at home and abroad have shown that areas that drink soft water for a long time have a higher incidence of cardiovascular disease. The hardness of tap water in China is controlled at 450 mg/L, which can be said to be relatively safe .
Drinking boiled tap water does not cause kidney stones. The real damage to the kidneys are the following three things, which should be avoided as much as possible in daily life:
1. Eat too salty
The kidneys metabolize 95% of the salt in our body. Excessive intake will further increase the burden of kidney filtration.
2. Like to hold back urine
Holding back urine can easily cause bladder damage. Urine retention in the bladder for a long time can also easily cause bacterial infection, which can easily lead to urinary tract infections, nephritis and other diseases.
3. Take medicine indiscriminately
Drugs also need to be filtered by the kidneys, not only the damage to the kidneys caused by the drugs themselves, but also the fact that the drugs will be recirculated through the kidneys with the blood and filtered through the kidneys. Therefore, using the wrong drug is the most toxic to the kidneys.
Tap water is drinkable and has no health risks. As long as it is boiled over a high fire and boiled for 3-5 minutes, the compounds have basically been volatilized. Of course, it is also possible for qualified families to drink filtered water. Drinking more water every day is the most important thing.
References:
[1] "Does chlorine in tap water cause cancer? So when steaming food, do you need to "boil the water first with the lid on"? 》. Nutshell.2017-03-27
[2] "@People who don't like drinking tap water, your body may be missing something "hard". Life Times. 2021-01-14
[3] The list of behaviors that hurt the liver, kidneys, stomach, and most organs is here! You may still be doing...". Popular Science China. 2019-09-29
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