After the soil is polluted by heavy metals or metalloid poisons, it often enters the human body through crops and water, causing moderate poisoning. Such as lead, mercury, cadmium, arsenic, chromium, thallium, etc., will cause various hazards to residents' health. Among them, the pain caused by cadmium pollution of soil is the most typical. Pain disease is a public hazard caused by cadmium-containing wastewater from prodigy Kawaguchi in Toyama Prefecture, Japan. The patient was in pain all over, crying day and night, hence the name pain. The main reason is that cadmium-containing wastewater pollutes farmland and enters rice, and residents get sick after eating rice with high cadmium content for a long time (called "cadmium rice"). Most patients are women of childbearing age. The main symptoms are osteoporosis, general pain, bending and deformation of limbs, compression and shortening of spine, multiple fractures of the whole body and difficulty in moving. The patient's urine has increased molecular protein, high cadmium content, increased urine sugar and changes in urine enzymes. The cadmium content in urine is as high as dozens of micrograms per liter, and the highest can reach 100 micrograms per liter (the cadmium in normal urine is below 2 micrograms per liter). Because cadmium damages renal tubules, it leads to abnormal renal function, disordered calcium and phosphorus metabolism, and increased urinary calcium, which leads to decalcification of bones. This disease usually occurs under malnutrition, and eventually, most patients die of extreme weakness and other diseases. The onset of the disease is slow, and the incubation period is 2 ~ 8 years. The biological half-life of cadmium in the body is 16 ~ 33 years, and it only happens after long-term accumulation. There is no effective treatment for the disease and the mortality rate is high. In addition to ensuring that the cadmium content in soil does not exceed the hygienic standard (1.0ppm), the World Health Organization also recommends that the cadmium intake of adults should not exceed 400 ~ 500 micrograms per week. The harm of chromium pollution to soil health is mainly hexavalent chromium. Hexavalent chromium is more harmful to health than trivalent chromium 100 times. The average content of chromium in natural soil is 50 ~ 100 ppm. Chromium pollution in soil mainly comes from industrial wastewater, waste gas and waste residue produced by chrome ore and metal smelting, electroplating and tanning. Chromium residue contains about 1% of hexavalent chromium, which is easily soluble in water and easily enters crops through soil, endangering the health of residents. The accumulation of chromium in the body can affect the redox process and hydrolysis process in the body. The combination of chromium and protein can inhibit the activity of some enzymes, promote the oxidation of vitamin C, denature hemoglobin and reduce the oxygen carrying capacity of red blood cells. Hexavalent chromium is a mutagenic substance, and Ames test and bone marrow cell nuclear test are positive. After investigation, the cancer mortality rate of residents in areas polluted by chromium slag such as Jinzhou and the western suburbs of Guangzhou in China is significantly higher than that in control areas. The harm of soil thallium pollution mainly comes from electronic industry, and lead, zinc, copper and other sulfide minerals also contain thallium (T 1). Waste water, waste gas and waste residue from smelting and industrial production pollute the soil and cause poisoning to residents. Thallium-containing slag reached 106 ppm at the foot of Zaofan Mountain in Xingyi, Guizhou, China, which was leached into soil by rainwater (thallium content in soil reached 50ppm) and absorbed and enriched by vegetables (thallium content in vegetables reached 1 1.4mg/kg). There have been more than 200 cases of chronic thallium poisoning among residents. The main symptoms are dizziness, headache, memory loss, insomnia, dreaminess, limb weakness, peripheral neuritis, decreased vision and alopecia (alopecia areata or alopecia totalis may occur). Thallium combines with protein or sulfhydryl groups of enzymes in vivo, causing cytopathic effects, mainly in brain, cerebellum, anterior horn cells of spinal cord and peripheral nerve cells. There are also lesions and necrosis at the distal end of the optic nerve fiber. Thallium also interferes with the activity of enzyme system related to potassium ion in vivo; Inhibit the physiological function of potassium granules, affect the excitability of myocardium and other neuromusculars, and cause various poisoning symptoms. Animal experiments show that thallium has mutagenic and teratogenic effects.