Coating standard: harm of heavy metals to human body and formulation of relevant standards

Abstract: the definition of heavy metal and its possible harm to human body are described in this paper, and the relevant international standards for heavy metal are listed Key words: heavy metal, hazard standard 1 What is heavy metal Heavy metal refers to metal with specific gravity greater than 5 (generally refers to metal with density greater than 4.55g/cm3) Heavy metals are metals with an atomic weight greater than 55 If the atomic weight of iron is 56, more than 55, it is also heavy metal There are about 45 kinds of heavy metals, which are generally transition elements Such as copper, lead, zinc, iron, cobalt, nickel, manganese, cadmium, mercury, tungsten, molybdenum, gold, silver, etc Application scope and advantages of roller ceramic coating Recommended introduction: the surface of ceramic rubber plate used for roller ceramic coating is cast into durable rubber plate by hundreds of independent small ceramic pieces Each ceramic piece has raised characteristics Under general conveyor belt pressure, thousands of unique cast bumps can produce positive traction, prevent slipping and extend the service life of conveyor belt roller At the same time, the bottom layer adopts high-quality rubber, which has strong elasticity and can play a good impact resistance role The scope of application of roller ceramic coating is one three six 83857180 (the same as V) 1 Roller coating in extremely harsh working environment 2 The belt joint is not suitable for fixing with iron buckle; 3 It is suitable for leather Abstract: This paper expounds the definition of heavy metal and its possible harm to human body, and lists the key words of international standards for heavy metal: heavy metal, hazard standard 1, what is heavy metal heavy metal refers to metal with a specific gravity greater than 5 (generally refers to metal with a density greater than 4.55g/cm3) Heavy metals are metals with an atomic weight greater than 55 If the atomic weight of iron is 56, more than 55, it is also heavy metal There are about 45 kinds of heavy metals, which are generally transition elements Such as copper, lead, zinc, iron, cobalt, nickel, manganese, cadmium, mercury, tungsten, molybdenum, gold, silver, etc Although manganese, copper, zinc and other heavy metals are trace elements needed for life activities, most heavy metals such as mercury, lead, cadmium are not necessary for life activities, and all heavy metals above a certain concentration are toxic to human body Heavy metals in terms of environmental pollution refer to those with significant biological toxicity, such as mercury, cadmium, lead, chromium (hexavalent) and metalloid arsenic There are five kinds of the most toxic to human body: lead, mercury, chromium (hexavalent), cadmium and arsenic These heavy metals can't be decomposed in water After drinking, the toxicity of these heavy metals will be magnified, and they will combine with other toxins in water to form more toxic organics Any kind of heavy metal can cause headache, dizziness, insomnia, forgetfulness, confusion of spirits, joint pain, stone, cancer (such as liver cancer, stomach cancer, colon cancer, bladder cancer, breast cancer, prostate cancer, blackfoot disease and deformed children), etc.; especially the cells, organs, skin, bones and spirits of digestive system and urinary system are seriously damaged 2 The harm of heavy metals to human body 2.1 the harm of lead to human brain cells, carcinogenic and mutagenic It is generally believed that the relative safety standard of blood lead should not exceed 10-14 μ g / L; long-term exposure to lead compounds or inhalation of metal lead dust will cause different degrees of "lead poisoning" (the concentration of lead in serum is more than 40 μ g / L); excessive inhalation of human body will harm human nervous system, heart and respiratory system, resulting in different degrees of lead poisoning; Lead in human body can combine with many enzymes to interfere with various physiological activities of the organism, resulting in harm to the whole body organs; the chance of lead poisoning in children is far greater than that in adults; the clinical characteristics are severe abdominal colic, anemia, toxic liver disease, toxic nephropathy, and multiple peripheral neuropathy The symptoms are dizziness, weakness, ache of muscles and joints, inability to eat, constipation or diarrhea, hepatomegaly, tenderness of liver area, jaundice and high blood pressure Medical examination: in addition to the significant increase of lead poisoning index, the increase of bilirubin and alt, the positive of RBC and WBC in urine, the positive of urobilinogen, the decrease of hemoglobin and RBC Nervous system examination showed glove socks hypoesthesia, muscle atrophy and myasthenia at the extremities 2.2 the harm of mercury sinks directly into the liver after ingestion, which greatly damages the vision of the brain The natural water contains 0.01 mg per liter of water, which will cause severe poisoning 2.2.1 the general symptoms of acute mercury poisoning are headache, dizziness, fatigue, low fever, sleep disorder, emotional excitement, excitability, etc.; the respiratory symptoms are chest tightness, chest pain, shortness of breath, severe cough, expectoration, and dyspnea; Stomatitis can appear in early stage, such as salivation, thirst, redness and pain of gingiva, mercury line can be seen on the tooth margin, swelling, erosion and ulcer of oral mucosa, loosening and falling of teeth, gastrointestinal symptoms are nausea, vomiting, loss of appetite, abdominal pain, sometimes diarrhea, watery stool or bloody stool; Mercury can cause renal tubular epithelial cell necrosis, edema, low back pain, oliguria or even urinary closure, positive urine protein, red blood cells and exfoliated epithelial cells in urine, and significantly increased urine mercury A few patients may have dermatitis, such as red papules, blisters, and severe rashes 2.2.2 neurasthenia syndrome of chronic mercury poisoning: dizziness, headache, insomnia, dreaminess, obvious memory loss, general weakness, etc.; excitability: manifested as restlessness, melancholy, shyness, timidity, excitability, boredom, anxious noise, fear, loss of self-confidence, inattention, thinking disorder, even hallucination, illusion, hearing loss, inconstancy of crying and laughing, etc; Autonomic nervous dysfunction: palpitation, hyperhidrosis, unstable blood pressure, blushing; hyposexual desire, impotence, menstrual disorders, etc.; stomatitis and gastrointestinal symptoms: metallic taste in the mouth, deep blue mercury line in the gingiva, drooling, thirst, gingival hyperemia, swelling, pyorrhea, ulcer, pain, loose teeth, nausea, anorexia, belching, diarrhea or constipation; Mercurial toxic tremor: tremor of fingers, tongue and eyelids, mostly intentional, aggravates when the attention is focused and the spirit is tense, and it is difficult to complete fine actions; severe patients may have coarse tremor; language is inflexible, stuttering, even eating and walking are difficult Others: a few patients may have kidney damage such as albuminuria, tube type and systemic edema, some patients may have rhinitis and upper respiratory tract inflammation, a few patients may have "mercurial" crystallitis in the lens of the eye, and some patients may have peripheral neuritis, such as hypoesthesia or allergy like gloves and socks 2.3 the harm of hexavalent chromium is a silver white luster metal, non-toxic, chemical properties are very stable, stainless steel will contain more than 12% chromium Common chromium compounds include hexavalent chromic anhydride, potassium dichromate, sodium dichromate, potassium chromate, sodium chromate, etc.; trivalent chromium dioxide (chrome green, Cr2O3); bivalent chromium oxide Among the chromium compounds, hexavalent chromium is the most toxic and trivalent chromium is nontoxic According to the research, chromium is the trace element for the life and health of mammals Lack of chromium can cause atherosclerosis Adults need 500-700 micrograms of chromium per day, while in general meals only 50-100 micrograms per day can be provided Brown rice, unrefined oil, millet, carrot and pea with brown sugar have higher chromium content Chromium can stimulate the growth of plants, and trace chromium can increase the yield of plants, but slightly higher concentration can inhibit the nitrification of organic matter in soil Chromic acid, dichromate and their salts can irritate and burn human skin and lead to contact dermatitis When these compounds enter the body in the form of steam or dust, they will lead to perforation of the middle nasal septum, gastrointestinal diseases, leukopenia, and asthma like lung diseases Skin contact with chromate can cause "Chrome sore" with very slow healing When the concentration of chromic anhydride in the air reaches 0.15-0.31 mg / m3, the nasal septum can be perforated Trivalent chromium is also a protein coagulant It is believed that hexavalent chromium can induce lung cancer In addition, hexavalent chromium, especially chromic acid, has a strong cultural effect on the metal pipeline of the water system The sodium dichromate with a concentration of 2 0.31mg/l can corrode the pipeline The trivalent chromium wastewater containing 3.4-17.3mg/l can make all plants poisoned When the hexavalent chromium in drinking water exceeds 400 times, the symptoms such as corner erosion, diarrhea, digestive disorder, shortness of breath, cough and asthma, short-term heart shock, toxic reactions of kidney, liver, nervous system and hematopoietic organs will occur 2.4 the harm of cadmium will damage the nervous system and cause acute gastroenteritis when ingested; excessive ingestion will accumulate in the kidney, cause damage to renal tubules and diabetes until renal failure Cadmium accumulation will cause bone ache in the whole body, cadmium poisoning will accelerate the loss of calcium in the bone, cause fracture or deformation, and cause pain in the whole body of patients;  chronic cadmium poisoning may cause prostate cancer and renal cancer in humans, lung cancer and testicular cancer in animals; cause blood pressure rise, and cardiovascular disease; the "pain and pain" in Japan, which shocked the world, is caused by cadmium pollution The cadmium contained mine waste water pollutes the river water and the soil, grain, forage on both sides of the river It enters the human body through the food chain and accumulates slowly in the kidney and skeleton It will replace calcium in bone, make bone soften seriously and bone broken Cadmium will cause dysfunction of stomach, interfere with zinc enzyme system in human body and organism, reduce the ratio of zinc to cadmium, and lead to the rise of hypertension Cadmium toxicity is potential Even if the concentration of cadmium in drinking water is as low as 0.1 mg / L, it can accumulate in human tissues (especially in women), with a incubation period of 10 to 30 years, and it is not easy to detect in the early stage The data show that the biological half-life of cadmium in human body is 20-40 years Cadmium is toxic to human tissues and organs in many ways, and treatment is extremely difficult, so far there is no specific method to treat cadmium poisoning. Therefore, all countries have made very strict regulations on Cadmium in industrial discharge of "three wastes" Japan also stipulates that rice containing more than 1 mg / kg of cadmium is "cadmium rice", which is forbidden to eat According to the Japanese environmental agency, 0.3ppm is the highest normal cadmium concentration in rice  2.5 the harm of arsenic is not strong in natural state, it will make skin pigmentation and lead to abnormal keratinization Arsenic compounds are often highly toxic The white powder we usually see, arsenic, is impure arsenic trioxide Arsenic trioxide (As 2O 3) is very toxic It can destroy some cell respiratory enzymes after entering the human body, so that the tissue cells can not obtain oxygen and die; it can also strongly stimulate the gastrointestinal mucosa, so that the mucosa can fester and bleed; it can also damage blood vessels, cause bleeding, damage the liver, and even die of respiratory and circulatory failure There are two symptoms of acute arsenic poisoning: gastrointestinal type, the most common The onset time varies with the size of the dose and the degree of gastric filling, 15-30 minutes fast, 4-5 hours slow, generally about 1 hour At the beginning, the throat felt burning, thirsty and nauseous, followed by severe abdominal pain and vomiting At first, the food was vomited, followed by yellow water, and at the same time, the diarrhea was severe At first, it was common feces, and then it was like rice soup Urine volume decreased, body temperature, blood pressure decreased, collapse, coma, and finally died of circulatory failure Neurotype, rare If a large amount of arsenic is taken at one time, it can cause severe circulatory failure, blood pressure drop, pulse fast and weak, superficial respiration and central nerve paralysis Its symptoms are dizziness, headache, muscle pain spasm, rapid unconsciousness, followed by respiratory paralysis, within 1 hour