List of "Science" Rumors in May 2022: Is outdoor disinfection necessary? Can cooking in an air fryer cause cancer?

The monthly "science" rumor list is guided by the Beijing Association for Science and Technology, the Beijing Municipal Cyberspace Administration, and the Capital Internet Association, and jointly released by the Beijing Science and Technology Journalists and Editors Association and the Beijing Regional Website Joint Rumor-Refuting Platform, and is supported by the Science and Technology Journalists and Editors Professional Committee of the China Science Writers Association, the China Evening News Science Editors and Journalists Association, the Shanghai Science Communication Association, and the Institute of Science and Technology Information of the Beijing Academy of Science and Technology.

1. Drinking milk can cause precocious puberty in minors

gossip:

Milk contains estrogen, which can cause precocious puberty in minors.

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the truth:

As long as you buy milk from a regular manufacturer, you don't have to worry too much about estrogen issues.

There are two sources of estrogen in milk. One is the natural estrogen secreted by cows during milk production, and the other is artificially added estrogen. The content of natural estrogen in milk is very low and is harmless to the human body. In fact, meat, soy products and other foods contain natural estrogen or estrogen-like hormones. Breast milk also contains estrogen, and the content is often higher than that of milk. As for artificially added estrogen, my country's "Regulations on Veterinary Drug Administration" has clear regulations on estrogen drugs, and related drugs must not be detected in animal foods.

Milk not only supplements calcium, but also provides high-quality protein and vitamin B2. The lactose in milk can also promote the absorption of minerals such as calcium, iron, and zinc. Many studies have shown that the intake of milk and its products can increase the bone density of children, adolescents, and postmenopausal women, which is beneficial to the growth and development of children.

2. The higher the city's groundwater level, the better

gossip:

Excessive exploitation of groundwater in cities will lead to geological disasters such as ground collapse, as well as environmental problems such as groundwater quality deterioration and water source depletion, so we should keep the groundwater level as high as possible.

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the truth:

If the groundwater level is too high, it may also bring unpredictable negative impacts to production and life. In cities, high water levels can easily threaten the safety of urban underground transportation and urban buildings. Therefore, the groundwater level should be maintained within a reasonable range according to the actual conditions of each place.

In fact, with the continuous improvement of the water ecological environment in recent years, some cities with rising groundwater levels have seen "strange phenomena". Last summer, a city in Hebei Province saw springs gushing out again, wells bubbling, and even underground garages in some residential areas gushing out water. Experts have concluded that this is closely related to the rise in groundwater levels.

In addition to urban buildings, the continued rise in groundwater levels will also harm agricultural production and even cause soil salinization.

In northern my country, due to long continuous sunshine hours and low relative humidity, if the groundwater level is too high, it will seep into the ground surface. After the water evaporates under the sunlight, what is left is salt. Over time, it will cause soil salinization and form saline-alkali land.

In the early 1970s, Beijing's groundwater level was also very high, and saline-alkali land appeared in the suburbs. In order to lower the groundwater level and ensure the safety of grain planting, wells were drilled and water was pumped out, which led to a downward trend in the groundwater level.

It can be seen that the reasonable groundwater level has an upper and lower limit change threshold range. Local management departments should strengthen monitoring and do a good job of "double control". They should control the total amount of groundwater withdrawal to keep it within a reasonable exploitation range, and also control the groundwater level within a reasonable range to avoid blindly pursuing the rise of groundwater levels under the general direction of ecological and environmental protection.

3. People who fall asleep in seconds have better sleep quality

gossip:

Compared to people who have difficulty falling asleep, some people can fall asleep quickly as soon as they lie down on the bed, which is a sign of good sleep quality.

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the truth:

Sleeping patterns and times need to be adjusted according to personalized lifestyles and habits. You can make a preliminary judgment based on whether the person is comfortable when he wakes up in the morning and his mental state. You cannot just look at how quickly you fall asleep.

In fact, sometimes falling asleep in seconds or falling asleep quickly does not necessarily mean that there is no problem with sleep, but rather it is a sign of disease. For example, many people with sleep apnea syndrome seem to sleep well, falling asleep in seconds when lying in bed, and snoring when sleeping, but this is not a sign of "sound sleep".

Repeated breathing pauses during sleep can cause ischemia and hypoxia in important parts of the body over the years, which can easily induce cerebrovascular disease, myocardial infarction, respiratory diseases, etc. Snoring is like a "silent killer" during sleep. People who are chronically sleepy or obese and snore frequently should seek medical attention in time to rule out sleep apnea syndrome. If these disease factors can be ruled out, then for healthy people, being able to "fall asleep in seconds" is a good phenomenon.

4. Large-scale outdoor disinfection is required in closed/controlled areas

gossip:

The new coronavirus strain of Omicron is more contagious, so it is necessary to carry out large-scale outdoor disinfection in closed and controlled areas.

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the truth:

Whether in the closed or controlled areas, there is no need for large-scale disinfection of the outdoor environment to avoid excessive disinfection.

"Eradication and killing" is an important means and content of health and epidemic prevention, which can effectively control the transmission of the virus. Existing studies have shown that the new coronavirus is mainly transmitted through droplets. At the same time, the higher the amount of virus in a unit space, the greater the probability of infection. Timely disinfection in local spaces can minimize the risk of infection. Especially in public places, such as government agencies, institutions, medical institutions, etc., it is extremely important to carry out routine disinfection.

However, in the natural environment, the new coronavirus cannot survive or can only survive for a very short time, so it basically will not cause the spread of the epidemic.

The possibility of viruses existing in outdoor ultraviolet environments is extremely low. Unless they are contaminated by viruses and must be disinfected, there is no need to carry out large-scale disinfection of these external environments. This will not only waste manpower, material and financial resources, increase social panic, but also affect the environment.

5. Displaying IP location will leak privacy

gossip:

The "IP territories" functions launched on major online platforms will leak user privacy and leave security risks.

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the truth:

The platform displays the user's "IP location". Domestically, it only displays the province (municipalities, autonomous regions, special administrative regions), and overseas, it displays the country (region). No more specific geographic location information will be displayed. Therefore, there is no need to worry that displaying the user's "IP location" will leak personal privacy.

In fact, the concern about privacy leakage is due to the confusion between the concepts of "IP location" and "IP address". Even if the specific IP address is known, the information displayed during the query is mainly the country/region/city, longitude and latitude, IP host name, Internet service provider, etc., while the user's name, exact address, phone number, etc. can directly locate personal information, which is difficult to obtain with just the IP address.

In contrast, IP location refers to the province where the IP operator is located, which refers to the location of the network access device rather than the location of the person. IP location information involves a large number of users, ranging from millions to tens of millions, and up to nearly 100 million. The granularity of location information is not enough to directly push to a specific individual identity through the province, and the recognition rate is still relatively weak.

6. Food cooked in an air fryer can cause cancer

gossip:

The air fryer is a "tax on your IQ" and the food cooked in it can cause cancer.

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the truth:

An air fryer is essentially a "high-efficiency oven." Because it uses forced hot air convection, its heating efficiency is higher than that of an ordinary oven. However, its impact on food is ultimately still heating through air. From this perspective, an air fryer "may produce carcinogens," but other similar cooking methods, such as frying, baking, and grilling, also produce them; if the amount produced is considered, an air fryer may even produce less.

In short, the air fryer is a relatively convenient "efficient oven" and there is nothing wrong with using it to prepare food.

7. The rice in the self-heating rice is fake

gossip:

It takes at least half an hour to cook rice in a rice cooker, but self-heating rice only takes 15 minutes to cook. It is obvious that the rice used is fake and has no taste at all.

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the truth:

Self-heating rice uses real rice, but in order to make it easier for people to eat, reconstituted rice is used. The reason why self-heating rice can be cooked quickly is that the rice has been soaked, steamed, separated and dried in advance.

Processed dehydrated rice (water content reduced to less than 10%) can be stored for a long time at room temperature and heats up much faster. However, compared with ordinary rice, the taste and aroma of self-heating rice are reduced. In order to restore the original taste of rice, many manufacturers grind natural rice or broken rice into rice flour, add konjac flour, edible corn starch, etc., and then press it into the shape of rice again. This is the so-called reconstituted rice.

The taste of rice made from reconstituted rice is different because the manufacturer adds adhesives during the processing, and some even add some trace elements and dietary fiber to increase the nutrition of the rice. In fact, in comparison, reconstituted rice is not only easier to cook, but also easier to digest than ordinary rice.

8. Iodized salt can cause thyroid nodules

gossip:

Nowadays, with the increasing abundance of seafood and other foods, it is no longer necessary to iodize salt. Eating too much iodized salt can also lead to a high incidence of thyroid nodules.

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the truth:

Even if people live in coastal cities with abundant seafood, they still cannot get enough iodine from food alone (adults need 150 micrograms of iodine per day), so it is still necessary to add iodized salt. The main reason for the high incidence of thyroid nodules in recent years is not that people eat too much iodine, but the progress and popularization of medical examinations, which have made nodules that were not discovered before visible.

Relevant research in my country shows that the detection rates of thyroid nodules in areas with sufficient iodine and areas with excess iodine are 21.8% and 20.7% respectively, which is not much different. There is no evidence that excessive iodine supplementation increases the incidence of thyroid nodules.

There is a U-shaped relationship between iodine and the incidence of many thyroid diseases. Too much or too little iodine will increase the incidence of thyroid diseases. However, the upper limit of "too much iodine" here is very high (800 micrograms per day), and it is not so easy to overdose in daily diet. In comparison, iodine deficiency is more likely to occur than iodine excess, and the harm is also greater.

my country's move to add iodine to salt has reduced the prevalence of iodine-deficiency-related mental retardation, premature miscarriage, congenital malformations of fetuses, and endemic goiter, greatly improved the iodine malnutrition of the Chinese people, and achieved the goal of basically eliminating iodine deficiency. Therefore, it is necessary to add iodine to salt for all people, and it is an important policy to protect public health.

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(Sources of this issue: Xinhua News Agency, Beijing Youth Daily, Beijing Science and Technology Daily, "Science Rumor Refutation" WeChat public account, Guokr.com, Tencent Jiuzhen, Rumor Refutation Platform, Health News, "Dingxiang Doctor" WeChat public account)