Cooking with raw water is not only toxic but also carcinogenic? Is there any scientific evidence? tell you the truth
"Xiaobao, buy a water purifier for your family on Double Eleven."
Xiaoya was lying on the bed chasing the drama, when she suddenly received a message from her mother, and replied casually, "Why are you buying that thing? And it's not cheap."
Then her mother forwarded an article to her - "Are you still cooking with raw water? People who don't know the truth may have been "broken"..."
Xiaoya clicked on the article, which mentioned that "raw water contains chlorine gas. Cooking with raw water for a long time will cause cancer, because chlorine gas has been listed as a 'carcinogen' by WHO ! Today, the editor is here for you. Recommend a water purifier***, which can effectively reduce chlorine in tap water..."
Xiaoya replied to her mother, "This kind of content looks fake, it must be selling water purifiers, and how do you know that the water filtered by the water purifier is really better than tap water?"
Mom: "...you seem to have a point in saying that, so don't buy it for now!"
Water is the source of life, but in the opinion of some people, cooking with raw water is still detrimental to human health. What is the truth? Does chlorine in tap water really cause cancer?
1. Cooking with raw water is not only toxic but also carcinogenic?
The reason why there is a saying that "raw water is carcinogenic" is mainly related to the chlorine added to tap water. Let's first understand why water plants add chlorine to water?
Untreated water in the natural environment tends to breed germs. In order to eliminate germs and meet drinking standards, water plants will purify tap water through chlorine disinfection technology.
The so-called chlorine disinfection technology is to put the chemical agent containing chlorine into the tap water, so that the chemical agent containing chlorine can combine with the bacteria in the tap water to achieve the purpose of killing the bacteria .
Under normal circumstances, a small amount of chloric acid and hypochlorite will remain in the tap water, so as to ensure a continuous inhibitory effect on bacteria during the delivery of tap water .
Therefore, some people worry that residual chlorine in tap water will harm human health.
Studies have indeed found that high-chlorine tap water may have certain health effects, such as increasing the risk of dermatitis, possibly triggering cholesterol and bladder cancer, etc., but it has certain limitations and is not generally recognized by the scientific community.
According to WHO regulations, the residual chlorine in tap water should not exceed 5mg/L. China stipulates that the minimum residual chlorine content in tap water shall not be lower than 0.05mg/L, and the maximum shall not be higher than 4mg/L.
In fact, in order to reduce health risks, the residual chlorine content in tap water is basically controlled below 1mg/L .
In addition, animal experiments and human experiments on chlorine-treated water have shown high safety. A human trial conducted in 1982 showed no adverse effects at a dose of 0.34 mg per kilogram of body weight.
Liu Qingjun, vice president and researcher of the Beijing Academy of Science and Technology, pointed out that in the thousands of water samples sampled and tested in the Beijing area in recent years, there has been no chlorine exceeding the standard.
China has high safety requirements for drinking water standards, coupled with the pungent smell of chlorine, when the chlorine content in the water is higher than 2mg/L, it can smell abnormal. So, as long as you don't smell irritating odor, don't worry, you can drink it with confidence .
2. Is the water filtered by the water purifier really better than tap water?
With the improvement of living standards, many families will install water purifiers. However, is water filtered by a water purifier really healthier than tap water?
In this regard, "Consumer Reports" conducted relevant tests, and sent water samples from northern water plants and other 6 groups of household water samples to testing institutions for testing of 20 indicators such as total hardness, total number of bacterial colonies, and turbidity. The results of the water samples were not significantly different.
On the contrary, no colonies were detected in the treated water samples of the water plant, and colonies were detected in the two groups of household water samples that did not replace the filter cartridges in time.
That is to say, the water treated by the water plant can be directly drunk with confidence, and the water purifier is more likely to breed bacteria if the filter element is not replaced in time .
So, is it necessary to install a water purifier at home?
An expert from the Department of Nutrition, School of Public Health, Sun Yat-sen University said that the water purifier mainly plays the role of filtration, adsorption, and ultraviolet disinfection, and the tap water has reached the sanitary standard of drinking water after treatment, and it can be drunk after boiling, so that it is not suitable for drinking. There is little point in using a water purifier.
Moreover, the water from the water purifier is not necessarily 100% safe. For example, if the filter element is not replaced for a long time, the water quality will cause secondary pollution.
Some people do not like to drink water, but in fact, there are many invisible nutrients in water. In addition to minerals such as calcium and magnesium, water also contains more than 40 nutrients such as sodium, potassium, chlorine, iron, and zinc.
Among them, calcium and magnesium elements contributed by water account for up to 20% of the total daily intake, and most of the other elements contributed by water account for less than 5% of the total intake.
3. Do you still believe these claims about "tap water"?
There are many "rumors" about tap water, have you heard of these?
1. After the boiled water is cooled = "chronic poison"
It is said that a large amount of carcinogen nitrite will be produced after the boiled water is cooled. In fact, China stipulates that the maximum limits of nitrate and nitrite in drinking water are 10㎎/L and 1㎎/L respectively. The allowable daily intake requires a lot of water, which is basically impossible to achieve.
Taking an adult male weighing 70 kg as an example, to achieve the allowable daily intake of nitrate and nitrite, he needs to drink 25.9L and 4.9L of water, respectively.
Therefore, the large amount of nitrite that is unlikely to be produced after the boiled water is cooled will affect the taste at most, or the bacteria will breed during the period of time.
2. The "shelf life" of boiled water is only 16 hours
If boiled water is placed for more than 16 hours, a large number of E. coli will breed. Drinking it will cause abdominal pain, diarrhea, nausea and vomiting?
In fact, there is no scientific basis for this claim, and E. coli is not airborne. Be aware, though, that E. coli can contaminate water sources through feces, so it's best not to drink raw water that hasn't been treated.
3. Scale in tap water can induce kidney stones
Most of the scale in tap water is because the water contains a lot of calcium and magnesium ions. According to Chinese standards, the total hardness of drinking water (calculated as calcium carbonate) does not exceed 450mg/L.
Calculated on the basis of adults drinking 2L of water per day, that is, 360mg of calcium intake, and the maximum tolerated intake is 2000mg. So as long as you drink water normally, it will not induce kidney stones.
Xiaojiu wants to remind everyone, don't wait until you are thirsty to drink water. If you are thirsty, your body is already dehydrated. It is recommended that normal adults drink a total of 1500-1700ml of water per day, do not drink too much at one time, drink a small amount and drink more, and drink about 200ml each time. The water temperature should be controlled, do not drink hot water over 65 ℃, 25-40 ℃ is appropriate.
All in all, tap water can be drunk with confidence, as long as it is drunk normally, it is beneficial and harmless to the body.
References
[1] "Wash your face directly with tap water, what may be the problem? 》. Nutshell. 2021-03-07
[2] "@People who don't like drinking tap water, your body may be missing something "hard". Life Times. 2021-01-14
[3] "Boiled water for 16 hours is comparable to "chronic poison"? The truth of these claims is revealed". People's Daily Online Science. 2022-06-12
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