Water is a rigid need of the human body, but it also raises a lot of questions:
Can't boiled water sit out for more than 16 hours?
Tap water contains carcinogens, can't drink it?
Do you have to drink 8 glasses of water a day? ......
How many of these rumors about drinking water have gone viral on the Internet? How many are fake? How do we drink water scientifically?
1. Boiled water also has a "shelf life", and you can't drink it after 16 hours?
The safety of boiled water will be further improved after boiling and sterilization, and only the physical properties such as temperature will change after cooling, but it will not change the chemical and biological safety, and it will not become a chronic poison.
It is rumored that boiled water will breed E. coli inside after 16 hours, and people will cause diarrhea, abdominal pain, fever and other uncomfortable symptoms after drinking. There is no scientific basis for this claim, and E. coli is not airborne.
Some scholars have conducted a special study for this purpose, and the researchers measured whether E. coli was present in the water after placing it at different nodes in the 5-17 hour interval without a lid and a covered group, and the results were not found.
However, in the process of cooling, it is necessary to pay attention to the safety and hygiene of the surrounding environment, if the hygiene is poor and it is not covered, the water may be polluted by microorganisms, dust, etc., which will affect the taste and safety of the water.
2. Tap water contains haloacetic acid, which can cause cancer when drunk often?
In 2022, the 15th edition of the carcinogen report released by the U.S. Department of Health and Human Services mentioned that haloacetic acid by-products produced after tap water disinfection are suspected to be human carcinogens.
Haloacetic acid is the second largest type of DBPs in drinking water after halomethane, which has a high risk of carcinogenesis, and is difficult to degrade and volatilize, which will increase the insecurity of drinking water. However, at present, each country has a clear limit on the amount of haloacetic acid in tap water, as long as it is a water source that meets the standards, there is no need to worry.
In addition, Dr. Jin Qiaog, from the Department of Environmental Health at the Shanghai Center for Disease Control and Prevention, said that when tap water is boiled, the so-called disinfection by-products will volatilize, so there is basically no need to worry.
There are not only rumors that tap water causes cancer, but there are also claims that "residual chlorine in tap water can cause cancer", but what is going on?
It is undeniable that chlorine is indeed a toxic gas, but in fact, the residual chlorine content in tap water is very low, or even not to the level of disease.
The WHO requires that the residual chlorine content in tap water is 5mg/L, and the continental limit requires that the residual chlorine content in tap water reach at least 0.3mg/L, and the maximum limit is 4mg/L, both of which are lower than the WHO standard, and the safety is guaranteed.
3. "Water boiled in an electric kettle" was also shot? Does nerve damage also cause cancer?
This statement has to be traced back to the early years, the "2016 Electric Kettle Product Risk Monitoring Quality Analysis Report" released by the Jiangsu Provincial Bureau of Quality and Technical Supervision. After hearing the association of the words "World Health Organization", "high manganese steel" and "carcinogenic", many people seem to have deep doubts about electric kettles overnight, and some people are even eager to abandon them like a piece of paper.
Some media added oil and vinegar to say that often boiling water in an electric kettle will also precipitate heavy metal elements, and long-term drinking of polluted water will lead to neurotoxicity and carcinogenesis, is this true?
It is true that there is manganese in the material used to make electric kettles, but it exists in the form of dense tissue, and it is difficult to precipitate it in daily boiling water.
Some researchers have conducted special studies on this and found that the precipitation of manganese from continuous boiling for more than 1,000 hours is also very limited, and the impact on the body is almost negligible.
Therefore, when buying an electric kettle daily, you only need to pay attention to choosing the production of regular manufacturers, and you don't need to worry too much.
People who often boil water will find that after using the kettle for a long time, it is easy to have a layer of scale at the bottom, will this layer of scale be harmful to health?
The appearance of scale is due to the presence of calcium and magnesium ions in the tap water, and after boiling, a chemical reaction will be produced to precipitate calcium carbonate, magnesium carbonate and other insoluble substances attached to the bottom of the kettle. The main components are carbonates, which will be partially broken down by the body when they enter the body, and some of them will be excreted with feces without affecting health.
4. Drink enough 8 glasses of water a day? You may have drunk the wrong one!
Drinking enough glasses of water a day seems to be the consensus of most people, but is it really scientific? Studies have shown that the principle of drinking water that you have been sticking to may be wrong.
According to a study in Science, 8 glasses of water a day (about 2 liters) is too much for most people, and people of different ages, genders, and countries need different amounts of water per day.
According to the researchers, the average daily water intake of men around 20 years old is 1.5~1.8L (6~7 cups); For women, the average daily average is about 1.3~1.4L (5 and a half cups).
The picture comes from the Internet
Although we drink water every day, what seems simple is not so simple, and many people do not drink water in the right way every day. According to the China Water and Quality of Life Perception Survey, about 95.3% of people in mainland China do not drink water. You must keep in mind the "3 Don'ts" when drinking water every day!
1. Don't wait until you're thirsty to drink
When you are thirsty, your body is already very short of water, so you should pay attention to developing a good habit of drinking water regularly, it is recommended to drink it once every half an hour, and the amount of water you drink each time is not too much.
2. Don't replace drinking water with drinks
There is a lot of sugar in the drink, and excessive intake can easily lead to obesity, diabetes, gout, etc., and it cannot replenish the water required by the body. It is best to use warm boiled water for daily drinking water, and you can make some flower tea if you can't drink it.
3. Do not drink water that is too hot or too cold
Water at a temperature of > 65 degrees can burn the esophageal mucosa, and long-term scalding will increase the risk of cancer; Excessively cold water will irritate the gastrointestinal tract and cause abdominal pain, diarrhea and other discomforts.
There are a lot of rumors about drinking water, but most of them are not credible, and we must learn to screen them and not let the rumors affect our normal life.
Resources:
[1] "Cooling with boiled water is comparable to "chronic poison"? Drinking water above 65°C often causes cancer? I'm going to tell you the truth today...". China Popular Science 2022-08-26
[2] "Drinking tap water causes cancer and grows stones...... Which of these rumors is true? 》. Family Physician 2016-08-04
[3] "Drinking water boiled in an electric kettle every day, damage nerves and cause cancer? These 3 types of water really need to be drunk less! 》. Popular Science China 2023-02-17
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