Heavy metals refer todensityMore than 4.5g/cmthreeOfMetal, includinggold、silver、copper、iron、mercury、lead、cadmiumThe accumulation of heavy metals in the human body to a certain extent will cause chronic poisoning.
In terms of environmental pollution, heavy metals mainly refer tomercury(mercury), cadmium, leadchromiumAnd metalloidarsenicAnd other heavy elements with significant biological toxicity.
Heavy metals are very difficult to be biodegraded. On the contrary, they can be enriched thousands of times under the biological amplification of the food chain and finally enter the human body.Heavy metals can interact strongly with proteins and enzymes in the human body, making them inactive. They may also accumulate in some organs of the human body, causing chronic poisoning.
densityAt 4.5g/cmthreeThe above metals are called heavy metals.There are 60 kinds of natural metal elements with atomic numbers ranging from 23 (V) to 92 (U). Except for 6 of them, the density of the other 54 kinds is more than 4.5g/cmthreeTherefore, in the sense of density, these 54 metals are all heavy metals.However, when classifying elements, some of them belong to rare earth metals and some are classified as refractory metals.Finally, 10 metal elements are really classified as heavy metals in industry:copper、lead、zinc、tin、nickel、cobalt、antimony、mercury、cadmiumAnd bismuth.These 10 heavy metals have metal commonness and density greater than 4.5g/cmthreeIn addition, there is no special commonality, and all kinds of heavy metals have their own properties.
Whether it is air, soil, or even drinking water, there are heavy metals, such as free radicals that cause aging, particles that are harmful to the skin, dust in the air, automobile exhaust, etc. Even tap water brings heavy metals to the skin, and even some heavy metal raw materials such as cadmium in some skin care products, such as skin lotion, are among them.The accumulated heavy metals are quite harmful to human body.
harm
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Human hazard
The common injuries of heavy metals to human body are:
mercury: After ingestion, it will sink directly into the liver, which will greatly damage the visual nerve of the brain.Natural water contains 0.1 ml per liter of water, which will cause severe poisoning.Drinking water containing trace mercury will cause cumulative poisoning if taken for a long time.
chromium: Can cause numbness of limbs and mental disorder.
cadmium: Causes hypertension and cardiovascular and cerebrovascular diseases;Destroying bone calcium, causingRenal dysfunction。
lead: Yesheavy metal pollution It is difficult to eliminate the more toxic one once it enters the human body.Direct injury to human brain cells, especially the neural plate of the fetus, can cause shallow cerebral sulci and hypophrenia;It causes dementia and brain death to the elderly.
The pollutants in water are complex and diverseToxic and harmful substancesThere are more than 1200 kinds, which can be roughly divided into five categories:
2. Agricultural pesticides and fertilizers;Chemical reagents, additives, etc.
3. Domestic garbage, waste water, sewage, excreta, etc.
4. Medical waste, virus, bacteria, corruption, etc.
5. Scientific research radiation, damage, chemical and radioactive pollution, etc.
Food contamination
Heavy metals generally refer to metals with a density of more than 4.5 grams per cubic centimeter, such as lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg), copper (Cu), gold (Au), silver (Ag), etc.Some heavy metals enter the human body through food, interfere with the normal physiological function of the human body, and endanger human health. They are called toxic heavy metals.Such metal elements mainly include lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg), etc.
However, the poisoning rate is very low, so there is no need to worry about these, but don't buy Sanwu products.This is just about the harmful consequences.
Heavy metal Hg:Main hazards to peoplecentral nervous system, brain damage, limb numbness, dyskinesia, visual field narrowing, hearing difficulties and other symptoms caused by mercury poisoning brain disease, even death due to heart failure.Severe poisoning can cause oral lesions, nausea, retting, abdominal pain, diarrhea and other symptoms, as well as damage to skin and mucous membranes, urinary and reproductive systems.Under the action of microorganisms,MethylationLater becomesMethylmercury, toxicity ratiomercuryLarger.
Heavy metal Cd:It can accumulate in the human body and cause acute and chronic poisoning. Acute poisoning can cause hematemesis, abdominal pain, and finally death. Chronic poisoning can damage renal function, destroy bones, and cause bone pain, osteomalacia, and paralysis.
Heavy metal chromium Cr:Irritating and corrosive to skin, mucosa and digestive tract, causing skin congestion, erosion, ulcer, nasal perforation, and skin cancer.It can accumulate in liver, kidney and lung.
As:Chronic poisoning can cause skin lesions, nervous system, digestive and cardiovascular system disorders, with cumulative toxic effects and destructionHuman cellsThe metabolic system of.
Heavy metal Pb:It is mainly harmful to the nerves, hematopoietic system and kidneys. It damages the bone hematopoietic system and causes anemia, cerebral hypoxia, brain edema, motor and sensory abnormalities.
Toxic and side effects
Heavy metals are often added in acne products, which is no longer a new topic. Most of them are added with mercury, which has whitening effect, and most of them claim that acne products have whitening and fade acne marks.But many people do not know that once these heavy metals penetrate into the skin and body, any of them will cause headache, dizziness, insomnia, amnesia, confusion, joint pain, stones, cancer, etc;Especially, the damage to cells, organs, skin, bones and nerves of digestive system and urinary system is extremely serious.It is difficult to metabolize heavy metals, and once precipitated in the body, it will bring a lot of harm to the body.[1]
Hazard prevention
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prevention
1. Try not to smell automobile exhaust.At the moment, the most likely thing for urban residents to be exposed to lead is car exhaust.The lead gas generated after the combustion of leaded fuel is inhaled by the human body, which can cause the increase of lead content in the body.If you are a car driver, a traffic policeman, or even just a resident living on the road, you may be trapped in the harm of lead if you often breathe in the exhaust gas of the car.Close the window when waiting for traffic lights to prevent inhalation.
2. Workers in some special industries, such as tin lead printing, are vulnerable to lead pollution;Electroplating workers are prone to high mercury content.However, it is not easy to lead to high lead if you often take newspapers and color printed materials, as long as you pay attention to washing your hands.
3. Try to choose environmentally friendly paint.Some paints and pigments also contain lead, which may lead to chronic lead poisoning if children swallow them carelessly.
4. Try to prevent the use of handicraft containers made of tin and lead to contain food.Some tin handicrafts are mostly made of tin lead alloy, which may lead into food and drinks.
5. Be careful when using liquid sphygmomanometer and thermometer.These tools contain mercury, which may cause mercury leakage if dropped carelessly.have access toElectronic sphygmomanometerThermometer instead.
6. When taking traditional Chinese medicine, it is necessary to pay attention to the amount and use method. Some traditional Chinese medicines are often highly toxic and have the effect of fighting poison with poison. This traditional Chinese medicine may contain strong toxic amounts of lead, mercury, arsenic, etc.
Detoxification
In case of acute or chronic heavy metal poisoning, or just high heavy metal content in the body, in addition to taking detoxification drugs according to the doctor's requirements, many natural foods have natural lead and mercury expelling functions.
1. The ovalbumin contained in milk can form insoluble substances together with lead and mercury, and the calcium contained in milk can prevent the absorption of heavy metals.It has certain rescue effect for acute lead and mercury poisoning.
2. Tannic acid in tea can form with leadSoluble complexDischarge with urine.
3. Iodine in kelp and acid of cauliflower can promote the excretion of lead.
4. The sulfide in garlic and onion can dissolve the toxic effect of lead.
5. Eat more fruits and vegetables.Rich in fruitsvitamin CIt can prevent the absorption of lead and reduce the toxicity of lead. The edible fruits of seabuckthorn and rattan plants contain higher vitamin C.Some inorganic anions or acid radicals, such as iodine ions, phosphate ions, molybdate ions, can be combined with lead to promote its excretion from the stool.[2]
Heavy metal detection
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Heavy metals mean that under experimental conditionsThioacetamideOr metal impurities developed by the action of sodium sulfide test solution, such as silver, lead, mercury, copper, cadmium, bismuth, antimony, tin, nickel, zinc, etc.Heavy metals can affect the stability and safety of drugs, so their content in drugs must be strictly controlled.There are many opportunities to introduce lead in the production process of drugs. Lead is easy to accumulate in the body and cause poisoning. Therefore, the heavy metal inspection is represented by lead, and the limit of lead represents the limit of heavy metal.
According to the fourth general rule of the Chinese Pharmacopoeia (2015 Edition), there are three methods for heavy metal inspection, namely, the thioacetamide method, the thioacetamide method after ignition, and the sodium sulfide method.The color developing agents used in the inspection are mainly thioacetamide and sodium sulfide test solution.Trace heavy metal ions (as Pb2+Is representative) and thioacetamide in acid (pH 3.5Acetate buffer）Hydrogen sulfide generated by hydrolysis under conditions, or reacted with sodium sulfide under alkaline conditions to generate yellow to brown black sulfide suspensionStandard lead solutionColored suspension generated by reaction under the same conditions shall not be darker.
1. The first method (thioacetamide method) is applicable to the detection of heavy metals in drugs dissolved in water, dilute acid and ethanol without organic damage.Take 25mLNessler tubeThree, plus in pipe AStandard lead solutionAfter a certain amount of 2mL of acetate buffer solution (pH3.5) is added, water or solvent specified under each category is added to dilute it to 25mL, 25mL of test solution prepared according to the method specified under each category is added to tube B, and the same weight of test sample is added to tube C, an appropriate amount of solvent is added to prepare the test sample solution to dissolve it, and the same amount of standard lead solution andAcetate buffer(pH 3.5) 2mL, dilute to 25mL with solvent;If the test solution is colored, a small amount of dilute caramel solution or other noninterference colored solution can be dropped into tube A to make it consistent with tube B and tube C;And then add in pipes A, B and C respectivelyThioacetamideShake 2mL of each test solution, place it for 2 minutes, place it on white paper, and see through from top to bottom. When the color in tube C is not less than that in tube A, the color displayed in tube B shall not be deeper than that in tube A.If the color in pipe C is lighter than that in pipe A, sampling shall be conducted for re inspection according to the second method.
2. The second method (post ignition thioacetamide method) is applicable to drugs that are insoluble or insoluble in water, dilute acid or ethanol, or are subject to certain factors (such as drugs with their own color, heavy metals in drugs are not free, or heavy metal ions form with drugsCoordination compoundInterfere with the heavy metal inspection of drugs that are not suitable for the first method of inspection.Take the specified amount of test articles under each variety, conduct ignition treatment according to the ignition residue inspection method, and then take the remaining residue;Or directly take the residue left under the item of ignition residue;If the test sample is a solution, take the specified amount of solution under each category, evaporate it to dryness, and then take the remaining residue after treatment according to the above method;Add 0.5mL nitric acid, evaporate to dryness until the nitrogen oxide vapor is completely removed (or take a certain amount of the test sample, slowly ignite it until it is completely carbonized, cool it, add 0.5~1mL sulfuric acid to make it moist, heat it at low temperature until the sulfuric acid is completely removed, add 0.5mL nitric acid, evaporate it to dryness, cool it until the nitrogen oxide vapor is completely removed, ignite it at 500~600 ℃ to make it completely ash), cool it, add 2mL hydrochloric acid, evaporate it on a water bath, and then add 15mL water,Drop ammonia test solution until the p-phenolphthalein indicator solution is slightly pink, then add 2mL acetate buffer solution (pH 3.5), after slightly hot dissolution, transfer it into Nessler's colorimetric tube, add water to dilute it to 25mL as tube B;Take another reagent to prepare the test solution, place it in a porcelain dish, evaporate it to dryness, add 2mL of acetate buffer (pH3.5) and 15mL of water to dissolve it slightly, transfer it to a Nessler's colorimetric tube, add a certain amount of standard lead solution, and then dilute it with water to 25mL as a tube A;Then add 2mL of thioacetamide test solution in tube A and tube B respectively, shake them well, place them for 2 minutes, place them on white paper, and see through from top to bottom. The color in tube B shall not be deeper than that in tube A.
3. The third method (sodium sulfide method) is applicable to the inspection of heavy metal impurities in drugs that are soluble in alkali but insoluble in dilute acid or precipitate in dilute acid.Take an appropriate amount of the test sample, add 5mL of sodium hydroxide test solution and 20mL of water to dissolve it, place it in Nessler's colorimetric tube, addSodium sulfideFive drops of test solution shall be shaken up, and the color shall not be darker than that of a certain amount of standard lead solution after the same treatment.[2]
Relevant national inspection standards
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GB/T 12496.22-1999 Test methods of wooden activated carbon Determination of heavy metals
GB/T 5009.74-2003food additivesMedium and heavy metal limit test
GB/T 20380.1-2006 Heavy Metal Content of Starch and Its Products Part 1:Atomic absorption spectrometryDetermination of arsenic content
GB 20424-2006 Limit Specification for Harmful Elements in Heavy Metal Concentrate Products
GB/T 17593.4-2006 Textiles Determination of Heavy Metals Part 4: Arsenic and Mercury Atomic Fluorescence Spectrophotometry
GB/T 17593.3-2006 Textiles Determination of Heavy Metals Part 3: Hexavalent Chromium Spectrophotometry
GB/T 20380.2-2006 Heavy Metal Content of Starch and Its Products Part 2: Determination of Mercury Content by Atomic Absorption Spectrometry
GB/T 20380.4-2006 Heavy Metal Content of Starch and Its Products Part 4: Determination of Cadmium Content by Electrothermal Atomic Absorption Spectrometry
GB/T 17593.1-2006 Textiles Determination of Heavy Metals Part 1: Atomic Absorption Spectrophotometry
GB/T 20380.3-2006 Heavy Metal Content of Starch and Its Products Part 3: Determination of Lead Content by Electrothermal Atomic Absorption Spectrometry
GB 20814-2006 Limit and Determination of 10 Heavy Metal Elements in Dye Products
GB/T 20432.5-2007 Photographic grade chemicals Test methods Part 5: Determination of heavy metals and iron content
GB/T 17593.2-2007 Textiles Determination of Heavy Metals Part 2: Inductively Coupled Plasma Atomic Emission Spectrometry
GB/T 7532-2008 Determination of Heavy Metals in Organic Chemical Products Visual Colorimetric Method
GB/T 9735-2008 Chemical reagent General method for determination of heavy metals
GB/T 6276.9-1986 Industrial useAmmonium bicarbonateDetermination of heavy metal content Visual turbidimetry
GB/T 22930-2008 Leather and Fur Chemical Tests Determination of Heavy Metal Content
GB/T 23950-2009 General Method for Determination of Heavy Metals in Inorganic Chemical Products
GB/T 7532-1987 General Method for Determination of Heavy Metals in Organic Chemical Products Visual Limit Method
GB/T 6276.9-2010 Determination of Ammonium Bicarbonate for Industrial Use Part 9: Heavy Metal Content Visual Turbidimetry
GB/T 9735-1988 Chemical reagent General method for determination of heavy metals
GB/T 10304.11-1988 Determination of Heavy Metals in Cathode Carbonate (as Pb)
Boric acid for industrial use Determination of heavy metal content (GB/T 12684.8-1990)
GB/T 13216.12-1991 Glycerin Test Methods Limit Test for Heavy Metals
