This article expert:
Xiaotian Zhang, Ph.D., School of Physics, Beihang University
Jie Liao, Ph.D., School of Biomedical Engineering, Beihang University
Bananas are sweet and soft, and are loved by all ages.
However, after eating for decades, I didn't know that bananas actually had radiation!
Many people think of CT tests, nuclear leaks, atomic bomb explosions: radiation causes cancer, is eating bananas carcinogenic?
What exactly is "banana radiation"? In today's talk about the discoloration of "spokes", can bananas still be eaten?
Why do bananas have radiation?
The essence of radiation is the transmission of energy, which can usually be divided into ionizing radiation and non-ionizing radiation.
Radiation with high enough energy to ionize atoms is called ionizing radiation, including CT examination, nuclear radiation, etc.; while low-energy radiation that cannot ionize atoms is called non-ionizing radiation, including radio waves, microwaves, etc.
Figure 1 Spectrum and properties of electromagnetic waves (Source: Wikipedia)
The reason why most people "talk about radiation discoloration" is mainly due to the harm of ionizing radiation.
Because the cells that make up our body are ultimately composed of atoms, once they receive high-energy radiation, the electrons in the atoms are attacked, so that the atoms they belong to make the atoms positively charged, then the material structure of the cells will change, thereby damaging the body, inducing cancer, causing infertility, and even causing fetal malformations and death. Therefore, ionizing radiation is very harmful to the human body.
So what kind of radiation does banana radiation belong to? Where does the radiation from bananas come from?
Bananas do have radiation, and they are discolored ionizing radiation. But there is no need to panic at all, because all talk of radiation hazards out of dose is unscientific.
The radiation of bananas is related to the potassium content.
Potassium is widely used in the form of salt in nature and is also one of the important components in human muscle tissue and nerve tissue. If the human body is deficient in potassium, it will lead to a series of problems such as irregular heartbeat and acceleration, abnormal electrocardiogram, and even cardiac arrest.
Potassium is innocent, not only has nothing to do with radiation, but is also very important to the human body.
But potassium has a sibling, potassium-40 (40K), which is an isotope of potassium and radioactive, and is one of the main sources of natural nuclear radiation for the human body, which means that potassium-40 causes ionizing radiation.
The radiation of bananas is derived from this radioactive element potassium-40. Because the potassium content in bananas is relatively rich in fruits, the potassium-40 content is relatively higher.
So how big is the radiation from bananas?
How much radiation does bananas have?
Direct answer: the amount of potassium-40 in bananas is like dust compared to the amount of radiation that can cause cancer.
People usually use the term "banana equivalent dose" to describe the amount of radiation, that is, the equivalent of "how many bananas were eaten" to measure the amount of radiation received.
We usually eat a banana, and the additional dose of ionizing radiation is about 0.0778 microsievert (the unit of calculation of the radioactive dose), which can be seen by the following comparison:
Chest CT scan is the equivalent dose of 70,000 bananas;
The maximum allowable radiation exposure of nuclear power plants to the surrounding environment is the equivalent dose of 2500 bananas per year, and the lethal dose is the equivalent dose of 35 million bananas, which means that 35 million bananas need to be eaten.
And our metabolism will control the potassium content in the body, even if we eat bananas, excess potassium will be excreted from the body, so bananas can be eaten with confidence.
What radiation is there around us?
Radiation in life is almost ubiquitous, non-ionizing radiation: electronic products or household appliances that we come into contact with, including mobile phones, computers, televisions, microwave ovens, flashlights, etc.; as well as radio broadcasting and communication transmission equipment, high-voltage wires and transformers.
The energy of this radiation is very low, basically harmless to the human body, do not worry.
Our common ionizing radiation is: subway security detector, X-ray examination, CT examination and so on.
X-rays and CT examinations are both examined by X-ray and belong to ionizing radiation, so these two tests should not be done too frequently, and they also need to communicate with the doctor before the examination.
The subway security detector is also through X-ray perspective on the object, but the radiation dose is far less than the X-ray machine used for medical diagnosis, do not worry about affecting health, but if you really mind, then when passing the security instrument, do not try to quickly and put your hand into the security detector to take the bag.
In addition, tobacco needs special attention, tobacco contains radioactive elements such as polonium-210 and lead-210. Smoking is harmful to health, and this harm is far from being comparable to that of bananas.
in a word
All talk of radiation hazards off the dose
It's all unscientific
Bananas have radiation
But the amount of radiation is very small
The radiation caused by cigarettes is more serious
For other radiation
All require reasonable analysis
Don't panic blindly
Source: Popular Science China