Radiation damage and chemical poisoning are two types of damage of different nature to the human body.

Radiation damage refers to the damage caused by ionising radiation to the human body. Usually it mainly involves alpha, beta, gamma rays, X-rays and neutrons. As the name suggests it is these rays that cause damage to human tissues through ionising radiation on their journey.
Chemical poisons such as cyanide, most heavy metals such as thallium, carbon monoxide, including alcohol, petrol etc. are not discussed here but should be distinguished from radioactive damage.

Types and basic properties of ionising radiation

X-rays and gamma rays and neutrons, are particles that are not themselves charged (without discussing the theory that they are all waves or other more modern theories). When they pass through the human body, they are harmful through the secondary effect of interaction with matter, which produces the ionising effect that occurs in charged particles (electrons, protons or other charged particles). Therefore, the reduction in the number of these non-charged particles as they pass through a substance is a roughly exponential decay, and unlike the charged particles described below, they do not have a fixed "range" and can theoretically penetrate materials of any thickness.
Alpha, beta and protons are charged particles that lose their energy through ionisation as they pass through matter, eventually losing all their energy and reaching their maximum range.
Alpha ray is a charged particle stream, has a strong ionisation instinct, due to its large mass, poor penetration ability, the range in the air is only a few centimetres, as long as a piece of paper or human skin can block it. At the same time, because of its energy concentration loss in a very small space, so the human body tissue destruction ability is larger.
Beta ray is a kind of high-speed charged particles, its ionisation ability is much smaller than α ray, but the penetration ability is bigger than α ray, usually the energy of β ray can be absorbed by a piece of aluminium foil or a certain thickness of plexiglass and other materials, but the range in the air can be up to a few metres.

Major sources of ionising radiation

Ionising radiation received by human beings comes from natural sources as well as from artificially produced sources.
Briefly, the main sources of artificial radiation are X-ray machines, particle accelerators, nuclear reactors and leakage from the manufacture, handling and discharge of various types of radioactive substances.
Natural radiation comes from the sun, cosmic rays and radionuclides present in the earth's crust. Cosmic rays from space include high-energy electrons, gamma rays and X-rays. The main radionuclides found in the earth's crust are uranium, thorium and polonium and other radioactive substances that emit alpha, beta or gamma rays. Radon, which spills out of the ground, is also an important source of radiation in nature.
X-ray sources, various particle accelerators and nuclear reactors usually have a relatively strict radiation management system, and the radiation they produce is often limited to a certain range. This article focuses on the radiation protection of the general population in general occasions, and does not discuss the protection of those nuclear facilities.
Since radiation is widely used in medicine, industry and other fields. The general population is inevitably exposed to a variety of man-made radiation damage other than natural radiation. For example, nuclear reactors and other auxiliary facilities, such as uranium mines and nuclear fuel plants, are bound to produce various kinds of radioactive waste, and some of them also leak a certain dose of radiation into the environment. In addition to this, the radiation dose from medical imaging equipment cannot be completely ignored. Radioactive materials are also widely used in people's daily consumption, such as luminous watches, glazed ceramics, artificial dentures, smoke detectors and so on.

Harmful effects of ionising radiation on the human body

In work exposed to ionising radiation, harmful effects can occur if the dose to the body exceeds a certain limit as a result of inadequate protective measures and violations of operating procedures. Under the action of electric radiation, the degree of the body's reaction depends on the type of ionising radiation, the dose, the conditions of exposure and the sensitivity of the body. Ionising radiation can cause radiation sickness, which is a systemic reaction of the organism, with pathological changes occurring in almost all organs and systems, but most markedly in the nervous system, haematopoietic organs and digestive system. Ionising radiation damage to the organism can be divided into acute radiation damage and chronic radiation damage. Acute injury can be caused by receiving a certain dose of radiation within a short period of time, which is usually seen in nuclear accidents and radiotherapy patients. While a longer period of time scattered to receive a certain dose of irradiation, can cause chronic radioactive damage, such as skin damage, haematopoietic disorders, leukopenia, impaired fertility and so on. In addition, excessive radiation can also cause cancer and cause foetal death and malformation.

Radiation damage to the human body can be divided into two categories: deterministic and stochastic effects (refer to Appendix III). There is a certain dose threshold for deterministic effects, the severity of which is related to the dose of irradiation, and the most common ones include haematopoietic dysfunctions, clouding of ocular crystals and cataracts, and benign skin injuries. The most common are haematopoietic dysfunction, eye crystal clouding and cataracts, and benign skin damage. Stochastic effects are dose-dependent, but there is no threshold. For example, the development of cancer is often the predominant stochastic somatic effect at low doses, and the genetic effects of somatic injuries in irradiated individuals that manifest themselves in their offspring are also stochastic effects of particular concern. Stochastic effects are a general term for a class of radiation-induced biological effects for which there is no dose threshold for the occurrence of the effect and the severity of the effect is independent of the dose, but the probability of its occurrence is positively correlated with the dose size.
Stochastic effects occur as a result of mutations in the genetic material of cells. In simple terms, cancer is the uncontrolled division and proliferation of cells. Normally, cells have the ability to control their own growth and division and proliferation, and likewise the ability to control the repair of damaged tissue. At the cellular level, the rays of ionising radiation act both directly and indirectly on the macromolecules in the cell that control these vital functions. damage to vital structures such as DNA interrupts the cell's control processes. If the cell loses control of its limited proliferation, these mutated cells have the ability to proliferate indefinitely, and this is where cancer arises. Another stochastic effect is the hereditary effect, which refers to the fact that there are no obvious somatic effects or clinical symptoms in the generation of parents who have been exposed to radiation, but their offspring develop congenital defects. The hereditary effect is that the radiation acts on the germ cells of the parents, causing damage or mutation of these vital cells, and the fertilised egg that results from their union may itself have major defects. As a matter of fact, we have not observed hereditary effects due to ionising radiation in the population, but only in laboratory experiments on animals. It should be noted in particular that we are surrounded by many carcinogenic agents that are far more likely to cause cancer and hereditary effects than radiation.