Are “prepared dishes” on earth healthy or not? Can they become a delicacy on the Spring Festival dining tables?


The monthly “scientific’ rumors list, guided by Beijing Association for Science and Technology, Beijing Municipal Cyberspace Administration Office and Beijing Internet Association and jointly released by Beijing Association of Science and Technology Journalists and Editors and, is supported by the Science Communication Committee of China Science Writers Association, the Society of Science Editors and Journalists of China Evening News, Shanghai Science and Technology Communication Association and Beijing Science and Technology Information Institute.

1. The eruption of Tonga volcano will result in “a summer-less year”


After eruption of Tonga volcano, huge amounts of volcanic ash enter the stratosphere where they cannot precipitate for long time, resulting in “sunshade effect” and leading to a “summer-less year” where global temperatures will drop. 


Volcanoes indeed would result in “cooling down” of the planet, mainly due to the fact that they inject sulfur-containing aerosol into the atmosphere, which would reflect more sunshine out after entering the stratosphere, thus generating cooling effect inside atmosphere. Over nearly 100 years, there were three large-scaled low-altitude volcano eruptions, namely, Gunung Agung, Indonesia (2019), El Chichon volcano, Mexico (1982) and Pinatubo volcano, the Philippines (1991). During the winter in the year of their eruptions, air temperatures in mot of China other than Northeast and Xinjiang were relatively low. 

But when it comes to climate impact, both the scale and gas emissions of volcano eruption are key factors that must be considered. The volcano eruption index (VEI) of Pinatubo volcano in the Philippines that once led to global average air temperature drop of 0.5℃ was level 6, and its 1991 eruption released 20,000,000 tons of sulfur dioxide; the estimated VEI of this Tonga volcano eruption is level 5-6, but the sulfur dioxide releases on the first day of eruption were merely 62,000 tons, an indication of moderate impact on the global temperatures that would not result in a “summer-less year”. 

A series of studies show that volcano eruption would generally produce continuous effects on global and East Asian climates in the next 1-2 years, resulting in a certain cooling effect. For China, volcano eruption might also weaken the intensities of East Asian summer monsoon in the next year, thereby resulting in relative southing of summer rain bands in China and affecting the rain precipitation of the entire flood season. 

Currently, Tonga volcano is still active and needs to be further monitored for its activities. If the volcano had no larger eruptions subsequently, it wouldn’t affect the global temperatures for the time being. 

2.  Getting fueled at morning and evening is more money-saving


The fuel charge of gasoline is billed based on volume, while according to the principle of thermal expansion and contraction, gasoline of the same quality would have smaller volume during early morning and evening due to low temperatures, so it is more cost effective to get fueled at morning and evening. 


The notion that getting fueled at morning and evening is more money saving is unwarranted. Currently, gas stations all have underground storage tanks equipped with protective layers of certain degrees, where gasoline is stored under constant temperature conditions for years and would not be affected by external temperatures. 

Even as the technology level in early years couldn’t reach the present standards to realize underground fuel storage at constant temperatures, gasoline would have little density changes under different temperature conditions, so the resulting price differences are minimal. 

3. Small wounds can be disinfected by merely saliva


As saliva contains “lysozyme”, small wounds on fingers can be disinfected by simply sucking them up with saliva.


Lysozyme is an important nonspecific immune factor in living organisms, which has such functions as antisepsis and anti-inflammation, increasing immunity and inhibiting exogenous microorganism growth. Although saliva contains lysozyme, it cannot play a disinfecting role if at all due to the too little content. In addition, the excretion of saliva is affected by numerous factors, including age, dietary habits and drug intake and life habits of people, so it varies from one person to another. 

Most importantly, applying saliva on wounds is mostly likely to worsen the situation. Because mouth is one of the areas where the human-resident microorganisms are mostly dense and varied, salvia also carries various viruses, funguses and bacteria of mouth. So, small wounds occurring in daily life are advisably treated by band aid and iodine. 

4. Fresh meats throb suddenly because of presence of parasites. 


On the eve of Spring Festival, every Chinese household begins purchasing goods for Spring Festival. But be careful if the meats you just bought would spontaneously throb, as this is an indication of parasites in meats. 


In fact, the freshly slaughtered meats would throb not because of parasites present but indicate they are just very freshly slaughtered. 

Shortly after slaughter, the central nerve of fresh meats have died, but nerve terminals surrounding muscles have not yet totally died, and the energy substance called adenosine triphosphate (ATP) in muscles have not been exhausted. Therefore, when slightly stimulated by the outside, muscles could also jitter, also known as “supravital reaction”. For a while after slaughtering, ATP in meats would be exhausted and muscular fibers would be locked up, meaning meats would no longer throb. 

5. Eating waxed apples is harmful 


If an apple has bright and smooth skin that feels viscous when touched and has powder falloff when scraped several times, it indicates the apple has been waxed and is toxic! 


Fruit wax is a kind of food additive allowed to be used worldwide, and would not harm human health as long as fruits are waxed properly. 

In fact, apples’ skins would naturally excrete a layer of fruit wax during the normal growth process in order to prevent harmful substances from intruding into pulp, which is a favorable measure for apples to fight external environments and not harmful to human body. 

Manually waxing fruits after harvest is an important part of the commercialized treatment process for fruits, with a view to preventing apple from losing moisture and shrinking on surfaces, which results in reduced freshness. Meanwhile, doing this can prevent microorganisms from intruding into fruits so as to prolong the shelf life.  

During the production and transport of apples, waxing is actually is a licensed operation. Many countries including China allow fruit surfaces to be waxed for keeping freshness. China’s Hygienic Standard for Use of Food Additives provides that morpholine fatty acid salt (aka fruit wax) and carnauba wax can be used as coating agents for application to surfaces of fresh fruits.  

Although proper waxing is not harmful to human body, many people might consider it not clean enough and want to thoroughly remove fruit wax before consuming. Experts said that the easiest way to remove wax from peels is peeling off. To preserve more nutrition in apples, an easy, good way is to flush them with hot water. 

6. COVID-19 vaccine dosage needs to be halved if administered to children


Most of drugs used for children are halved or appropriately reduced when administered based on drug dosage for adults. COVID-19 vaccine dosage needs also to be halved when administered to children, otherwise bodies would be “overloaded”. 


At present, COVID-19 vaccine dosage and components for all age brackets including children are exactly the same. Adopting a unified dosage while ensuring safety proves to be a universally accepted solution. Dosage of therapeutic drugs would consider body weight and in some cases the body surface area, which are related to the pharmacokinetic studies of drugs in bodies and liver metabolism, among other factors. 

But the mechanism by which vaccines function is different from that of therapeutic drugs in that antigen in vaccines does not directly “work” when entering human body, but instead perform antigen presentation via the immune system, producing antibodies after immune cell recognition before antibodies play a role in blocking viral infection or preventing onset of diseases. The aforesaid process has nothing to do with body surface area or body weight. 

In fact, dosages of the vast majority of vaccines make no distinction between adults and children. For example, there is no dosage distinction among populations for hepatitis B vaccine, cervical cancer vaccine and pneumonia vaccine. In terms of mechanism, the mechanism via which vaccine generates antibody after entering bodies of children is the exactly same as adults. 

Immunization program experts said that attention needs to be given to health condition of children when administering the COVID-19 vaccine, because children aged above 5 might have some psychogenic reactions and children older need to avoid intense exercise by staying onsite for 30 minutes of observation. If children vaccinated exhibit any condition suspected to be related to adverse reaction, immediately reporting is required. If administration of other immunization program vaccines happens to coincide with non-immunization program vaccines, one must ensure there will be more than 14 days between COVID-19 vaccination and inoculation of other vaccines. 

7. Prepared dishes are not fresh and contain preservatives 


Compared with fresh dishes, the hottest “prepared dish” for this year’s Spring Festival dining is already not fresh after being frozen and reheated, and some prepared dishes even have a shelf life of one year, presumably containing additives and preservatives. 


Prepared dishes are no different from the foods we eat everyday, and contain no additional preservatives. Normalized and traceable production and preparation process would make dishes more stable in taste and safer in quality. 

Factory-prepared dishes are standardized production and can have its taste reproduced once heated on gas stove at home, to a level comparable with freshly made dishes in restaurants. 

The vast majority of prepared dishes need to be cooked at high temperatures, which itself is a sterilization process; then they are frozen at ultra low temperatures using quick freezing technologies such as liquid nitrogen in a way that can totally inhibit microorganism breeding, thus eliminating the need for additional preservatives. 

On the other hand, prepared dishes are required to list all ingredients according to packaging standards, so related additives contained in seasonings would appear in the ingredient table. 

But this does not mean prepared dishes include more additives than dishes freshly made in restaurants or at home. Even foods purchased and cooked by consumers often contain additives. For example, numerous soy sauce products contain sodium glutamate and potassium sorbate, while some flavorings contain hydroxy propyl distarch phosphate and citric aid, etc. Reasonably used additives would not be harmful to human body as long as they comply with the national additive standards. 

8.  “Cold fireworks” are safe to set off due to low temperatures


As its name implies, “cold fireworks” are not classified as dangerous articles as such fireworks due to low setoff temperatures. 


The so-called “cold fireworks” would be somewhat misleading in that they are not only fireworks but also did not change their basic attributes of flammable and explosive articles. 

When “fairy stick” and “electronic fireworks” are set off, the temperature after flame (spark) burst-out rapidly decreases, to about 80℃ at 20cm away from the ejection point and about 40℃ at 50cm away from the ejection point, so they are nicknamed “cold fireworks”. When setting off such products, the temperature at the ejection point is as high as 700-800℃, still capable to burn human body and ignite flammables. 

Therefore, when producing, dealing in, storing and setting off “cold fireworks”, it is still necessary to strictly comply with safety rules regarding fireworks. When setting off “cold fireworks”, members of the general public should take safety measures generally applicable to firework products and are prohibited from setting off them indoors or at any place prohibited from setting off fireworks. 

9. Wearing diapers would give babies “O-shaped legs” 


Diapers would make babies’ legs unable to close together and give them “O-shaped legs” when they grow up! 


 “O-shaped legs” have nothing to do with wearing diapers. Fetuses appear crouched while in their mothers’ bellies, with two legs appearing O-shaped, a leg shape that would continue to two years old after birth of fetuses, which is normal.  

After turning 2 years old, as babies learn to walk and squat, in order to accommodate physiological needs, their lower limbs would self adjust and gradually turn into “X”-shaped appearance, which often becomes most obvious when they turn 4 or 5 years old. After turning 6 years old, the radian of “X” shape would gradually decrease and their legs would gradually appear the same as adults when they turn 7 or 8 years old. 

The present-day disposable diapers are designed to have little restrictions on leg activities of babies, allowing legs to naturally stretch and enabling normal development of joints and muscles through regular exercise. Hence, “O-shaped legs” of babies under 2 are a normal developmental condition, not caused by wearing diapers. If abnormalities indeed occur, they must not be ignored and moms must have their babies diagnosed and treated by doctors at hospitals, instead of attempting to correct by themselves. 

Content sources of this issue: 

Xinhua News Agency, CCTV Channel 2, CGTN,,, Science and Technology Daily, Farmers Daily,, Economic Daily, China Science Communication,,, Publicity and Education Center of the Ministry of Emergency Management, client of Beijing Daily, Beijing Science and Technology Report, Beijing News, official WeChat account of “Rumor Filter”,, official WeChat account of “”,, official WeChat account of 

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