Do mothers need to wear anti-electromagnetic radiation aprons?

Host: Liang Feng

Guest: Dr. Shi Wei, General Institute of Military Equipment, General Logistics Department

To meet the arrival of new life, expectant mothers have done enough preparation work, especially ladies who work in front of office computers. As long as they wear anti-electromagnetic radiation, they declare that they have become mothers.

Does a bellyband have anti-electromagnetic radiation effects on the body? On this issue, this reporter consulted Dr. Shi Wei of the Military Equipment Research Institute of the General Logistics Department.

A bellyband cannot prevent radiation in all directions

Moderator: Dr. Shi, we will first give you a conclusion. From the perspective of a scientific worker, do you think that the prevention of electromagnetic radiation radiation aprons on the mother and the fetus has no protective effect?

Shi Wei: There is no role to consider from all aspects. Since the electromagnetic radiation is all-dimensional and three-dimensional, when mothers only wear one apron, the electromagnetic wave can still radiate from the back, so basically there is no anti-electromagnetic radiation effect. Unless this radiation source is in front of the human body, it may have a little effect.
Three major effects cause damage to the human body

Moderator: What are the damages to the human body caused by electromagnetic radiation?

Shi Zheng: Electromagnetic radiation has become the fourth largest source of pollution in the world after air pollution, water pollution and noise pollution. When the electromagnetic radiation intensity exceeds a certain limit, it will pose a threat and harm to human health. Electromagnetic radiation damage to the human body stems from the thermal, non-thermal, and cumulative effects of electromagnetic waves.

The thermal effect refers to the physiological and pathological changes caused by heating of the human organs caused by electromagnetic radiation. Like food in a microwave oven, it heats up under microwave radiation; microwave weapons focus the microwave energy to burn a goat instantly. This situation is basically not encountered by the public.

The non-thermal effect means that although the biological organs are not warmed by the electromagnetic field, the human organs act as a delicate electromagnetic device, which may cause dysfunction due to the failure to achieve good electromagnetic compatibility under the action of external electromagnetic fields. This kind of damage is a bit like the interference between two electronic devices. Just like placing the mobile phone near the TV, the phone will cause audio and video interference. The human body is also a precision electronic instrument (electrical signals such as electrocardiogram and electroencephalogram). The human body is exposed to the electromagnetic field and will interfere with the electrical signals of the human body. When the human body is disturbed, it will feel or not feel the adverse effects. . But apart from long-term exposure to radiation, there is no problem leaving the electromagnetic field.

European researchers believe that non-thermal effects can cause human injuries, and American scholars believe that non-thermal effects will not cause damage to the human body. Therefore, the limits of human electromagnetic exposure defined by Europe and the United States are nearly one thousand times different.

Accumulation effect refers to that although the electromagnetic field intensity of the environment in which the human body is located is lower than the exposure limit, the long-term exposure to radiation can cause damage due to the cumulative effects of radiation effects. Some scholars have also combined the effects of accumulation into non-thermal effects, and believe that there are only two types of thermal effects and non-thermal effects.

The main organs of electromagnetic waves are sensitive organs such as eyes, reproductive organs, brain, heart, and thyroid. Mild damage to the human body from electromagnetic radiation usually manifests itself as symptoms of feeling fatigue, memory loss, insomnia, dreaminess, hair loss, and dizziness; long-term effects of strong high-frequency electromagnetic fields may also lead to cataracts, leukemia, and brain tumors. Vascular diseases, brain dysfunction, and serious injuries such as women's miscarriage and infertility can even lead to low levels of human immune function, causing cancer and other diseases.

Since the main action organ of electromagnetic waves is the eye, the turbidity of water crystals caused by microwave radiation is most likely to cause and the sediment is cataract. Therefore, if there are no clinical symptoms in this area, it means that the harm to the human body is not very serious. Even the radiation under high electromagnetic fields belongs to non-ionizing radiation. That is, the electromagnetic wave wavelength of the above-mentioned electromagnetic radiation pollution source is still in the microwave band. Such electromagnetic wave wavelength does not directly cause the ionization of ions of the substance molecules (including molecules in the human body), and generates ions. It triggers subsequent chemical reaction and reaches the level of heat generation at most, so it will not produce ionizing radiation damage caused by high-energy radiation such as X-rays, gamma rays, and electron beams.

Because the earth has a negative charge of about 900,000 coulombs, and a positively charged ionosphere at an altitude of several tens of kilometers from the ground, an electric field perpendicular to the ground is formed from the surface to the upper air. At sea level, the electric field strength on sunny days reaches 120 V/m. Because human beings evolved in such an electric field environment, there is really no need to worry too much about electromagnetic fields. At present, the use of electromagnetic fields to treat patients is still a large class of effective physical therapy methods.

Whether the need for protection is judged by the standard

Moderator: What standards have been established in China for electromagnetic radiation?

Shi Wei: Since 1988, China has drafted six relevant standards by the Ministry of Health, the National Environmental Protection Agency and the Ministry of Electronics. Due to the confusion between the standards, in 2001, China joined the WHO International Electromagnetic Exposure Exposure Standards Coordinating Working Group and organized a Ministry of Information Industry, the Ministry of Health, the State Environmental Protection Administration, the State Administration of Radio, Film and Television, the State Power Corporation, and the General Administration of Quality Supervision, Inspection and Quarantine. A joint working group for the development of national standards for electromagnetic radiation, including six ministries and commissions, has merged the six existing national standards, and on this basis, it has completed the exposure draft for electromagnetic radiation exposure and measurement methods. The preparation of this standard was completed in March 2001 and completed in December and was widely released to the public and solicited opinions. This draft has the following characteristics: “Draft for Soliciting Opinions” is jointly decided by six ministries and commissions, which can change the status of the inconsistency of domestic electromagnetic protection standards; the “Draft for Soliciting Opinions” applies to the frequency range of 0 to 300 GHz, including the industrial frequency; The meaning of the term “electromagnetic radiation” in the standard can be extended to cover the electromagnetic induction phenomenon and solve the industry’s dispute over whether “electromagnetic radiation” is reasonable in industrial frequency; it is clear that exposure limits are not safe and hazardous. The boundary is only an acceptable upper limit of the protection level; according to the different frequencies of the electromagnetic field on the human body, different basic limits are proposed, and the derived limit is convenient for actual operation; the exposure limit value is lower than ICNIRP , that is, to some extent consider the non-thermal effect.

However, as the ministries and commissions proceed from their respective business and academic points of view, the final standard drafts cannot be unified and are still at the stage of “drafts for comment”.

In addition, the electromagnetic protection national army is marked with seven standards: GJB 7-1984 microwave radiation safety limits, GJB 475-1988 microwave radiation living area safety limits, GJB 3861-1999 shortwave radiation exposure limits and measurement methods. In response to the long-term implementation of the seven standards and the somewhat confusing content, the General Armament Department took the lead in merging seven national military standards involving electromagnetic protection. It also took into account the concept of “exposure limits” and redefined the “limits of exposure”. "The value of" GJB 5313 "electromagnetic radiation exposure limits and measurement methods" standard, in 2004 issued a formal version.

It can be considered that the two "Electromagnetic Radiation Exposure Limits and Measurement Methods" standards, which have been merged together, are the basic basis for China's environmental electromagnetic field allowable intensity and human exposure limits. Although one of the national standards still stays at the draft stage of the draft, its predecessor is the six national standards, so its technical content can still be trusted. The exposure limit value of GJB5313 is also more stringent than the “draft for comment”, which is a higher standard that can be used as a basis for designing shielding effectiveness of electromagnetic radiation protective clothing.

Therefore, whether the public needs to wear electromagnetic shielding protective clothing, as long as the exposure limit under the corresponding frequency proposed by the above-mentioned standards, and the actual electromagnetic field strength of the environment, can be concluded.

Shielding and spacing control radiation

Moderator: What objects will produce electromagnetic radiation on the human body?

Shi Wei: In addition to natural electromagnetic radiation pollution due to natural causes such as solar storms, thunderstorms, and volcanic eruptions, the electromagnetic radiation pollution that causes harm to mankind mainly stems from artificially generated radiation sources, including radar, radio and television transmission equipment, and communications. Base stations, electromagnetic machining machines, medical instruments, scientific research equipment, high-voltage power equipment, vehicles, and various electrical and electronic equipment. According to its structural characteristics and working conditions, the above-mentioned radiation sources can be divided into open radiation sources (such as radars, communication base stations, etc.) that directly transmit electromagnetic waves to cause damage to human bodies; and closed-cell radiation sources (such as microwave ovens and other electrical equipment) are accidentally leaked. Electromagnetic waves cause radiation damage to the human body.

For the public, the most easily exceeded standard is the induction cooker. It has greater power, but it is between closed and open; followed by high-voltage power transmission and transformation equipment, and sometimes it is exposed to radiation. However, most of the power transmission equipment in the vicinity of the ground electromagnetic field intensity is also in line with the exposure threshold, only in bad weather conditions may be exceeded.

Moderator: In the face of electromagnetic radiation, how should we protect it?

Shi Wei: There are two control methods, one is shielding method: For microwave ovens and other closed sources of pollution, the use of metal shell shield can achieve a reliable shielding effect. The second is the interval method: For open source pollution such as communication base stations, in addition to professional personnel operating and maintenance needs to be close, the general public should not be close to these open sources of pollution, including high-voltage power transmission and transformation equipment. Therefore, the general high-voltage power transmission and transformation equipment and residential areas are very far apart, and design requirements have been taken into account. Electromagnetic radiation that may be exposed to high-voltage lines does not cause damage to the human body because of the short duration of time.
Cell phone caused brain tumor has not been scientifically confirmed

Moderator: How to protect the professional crowd?

Shi Wei: Protection methods for occupational groups: Electromagnetic radiation protection suits used in strong electromagnetic fields are completely enclosed. If there are holes in the fabric and there are gaps in the structure of the clothing, the shielding effect will be seriously affected.

It is generally believed that in special workplaces where radiation injury may occur, practitioners are required to wear electromagnetic radiation protective clothing when carrying out work activities under strong electromagnetic fields. However, for the public living environment and the general working environment, under the national electromagnetic health standards, the electromagnetic compatibility requirements of electrical equipment and the supervision and management of the environmental protection department, there is no electromagnetic field intensity exceeding the safety limit under normal circumstances; even the radiation intensity The argument that a strong mobile phone has caused brain tumors has never been confirmed in a scientific sense. Just as air pollution, water pollution, and noise pollution do not allow the public to use appropriate protective equipment, just because the government's environmental management department does the pollution control, it does not require the use of protective equipment for the public. The suggestion that mothers and mothers wear protective clothing for radiation belongs to the category of business behavior rather than the conclusion of medical science.